FORD E-250 BRAKE / TAIL LIGHTS STAY ON (PART 1)

[Music] hey guys what's up it's Eric with the advanced level automotive welcome back to the channel today we have another case study right behind me we have a 2005 Ford e-250 van it's got the v8 4.6 liter engine and customer complaint is that the brake lights are staying on now the customer already tried replacing the brake light switch but it still didn't fix a problem he also went through and started pulling fuses and he noticed that when he came across one of the fuses the brake lights would go off and that's how he kept the battery from dying overnight so anyways they brought us a truck they wanted to check it out let's go ahead and get started alright guys so before we get started let me take you inside the vehicle real quick now like I said the customer said that he pulled a certain fuse and he was able to get the brake lights to go off and what he said was the fuse box under here he already took the fuse out and just so I knew where it went he said that he installed the fuse backwards I think I see where it is I believe it's this one right here let's see how he just kind of had it in there backwards so it's a 20 amp fuse and it looks like it goes into slots number 10 now of course this is a Ford so they don't tell you what the fuse slot is for we're gonna have to look at the manual to see what fuse number 10 is for but for now I'm gonna go ahead and stick this fuse back in and we're gonna see if the brake lights stay on so so let me go ahead and install this fuse and we have our fuse number 10 installed now let's go to the back of the vehicle and see if the brake lights are on all right so we're at the back of the vehicle as you can see our rear brake lights are on now I don't know if I would call them brake lights because it is possible that we're not dealing with the brake light circuit maybe it's an issue with the tail light circuit because if you look up here the third brake light is not illuminated now that may be just because the third brake light bulbs are out that's real common on these things they tend to get water intrusion and those bulbs tend to go out so like I said we may be dealing with brake lights we may not be it may just be the tail lights that are on but either way these lights are staying on and I mean I forgot to tell you guys but the key is not in the ignition let me show you key is sitting on the seat right here and the ignition is not on now when I turn the ignition on you'll see that our lights are still on so let's go to the back so I guess the question here is are we dealing with a brake light circuit problem or are we dealing with the tail light circuit problem and like I said the customer did say that he already replaced the brake light switch and if I'm not mistaken I believe the box for the part it's right here it's the brake light switch that he replaced as you can see it is installed and plugged in connector is nice and secured and it's installed properly so doesn't look like we have a problem with the brake light switch now I think we all know what the next step is we need to go ahead and pull up the wiring diagram for this circuit and see how it works all right everyone so we're back here at the computer and I've got the wiring diagram pulled up for the exterior lamp circuit you already know how we do this we're gonna go ahead and look at the overview of how the system works and then we're gonna see if we can diagnose the problem so we're gonna start by looking at the brake light switch which is located right here now this is a switch that's on the brake pedal and whenever you depress the switch you're going to close a circuit normally it's an open state and when you press the brake pedal you're going to close switch that's going to allow power to float through the switch and if you follow this back up the power comes from this 15 amp fuse which is fuse 11 that's located in the central junction box that's behind the left side of the - that's the fuse box that we looked at earlier where that fuse number 10 was located that we pulled so anyways power is gonna flow from this 15 amp fuse it's going to go through this light green and red wire then it's going to travel through the brake pedal switch whenever you close it and then it's going to go off over here to a splice when it gets to the splice to power from the brake light switch is going to go off to several different places if we look up here you'll see that it goes to the powertrain control module over here it goes over to the ABS module and over here it goes to the brake shift interlock and if we follow it down here you'll see that it goes back to the central junction box and it goes through fuse 39 which is a 10 amp fuse and if you follow it down it goes to yet another splice so this power feed gets really spread around I'm gonna go ahead and move it so we can focus more on this splice if we follow it this way you'll see it goes to this resistor and then if we follow it this way it goes off to the trailer electronic brake control connector if we follow it down this way you'll see that it goes to the high mounted stop lamp and then if we go back up you'll see that it goes from the splice over to the multifunction switch and inside the multifunction switch if we look at the circuitry that's in here it's a bunch of switches but I believe somehow the power from the brake lights brake lights which goes through the multifunction switch and it comes out on both of these wires here and then it goes to the rare lamp assemblies so if you follow down over here there's a rear lamp assembly over here then we have another spice over here you follow that wire you'll see it goes down to this over here stop lamp turn lamp if you follow this one will follow it back up over to that wire so oh the way this is is the diagram is actually separated so over here this is for the cutaway van now this is not a cutaway van this is just a normal band so we look over here this it's got the dotted line that'll take you across over here and it goes to the right rear stop lamp and then the other one goes from here over to the left rear stop lamp right here so hopefully that makes sense to you guys now if we move back up to the top of the diagram let me go ahead and deselect all of this and we'll move back to the top of the diagram okay so what we just went over is how the rear brake lights get their power source and again they get their power source through the brake pedal switch which then goes through the multifunction switch and out to the rear exterior lamps so that's how the brake light system works and again we're not even sure if we're dealing with the problem with the brake light system like I said the rear lights there's also the tail lights there's also the turn signal lights hazard lights and we could have a problem anywhere in the circuitry that's keeping those lights on so again that's how the brake light system works moving on to the next part of this diagram if you look over here this is fuse number 10 it's at 20 amp fuse that we pulled out of the fuse box this is the one that the customer said that whenever he removes it the lights go off that's a good indicator that we may have a problem with the circuit that gets fed by this fuse 10 so what I'm gonna do is I'm gonna highlight this fuse 10 power feed and we're gonna see where it goes so if you follow it down the wiring diagram you'll see that it goes to the main light switch so this is the headlight switch and tell light switch so this switch whenever it's on it feeds the headlights and the tail lights so if we follow the power source through the main light switch we follow it out and we'll see where it goes it goes to several different power feeds but if we look at it it goes over to the rear lights so again this is for the rear tail lights the power source comes through the main light switch goes through a couple of spices and it gets fed out to the rear tail lights so is it possible that we have a problem with the main light switch it is possible it's possible that maybe we have an internal problem with the main light switch it's probably keeping the circuit closed and it's continuously feeding power out to those rear tail lights I'm not sure but I think one of the things that we could try to do is maybe just unplug the main light switch it looks like it's pretty easy to get to we may as well try to unplug it and maybe while we're down there we can probably just to sure we can unplug the brake pedal switch because if we unplug this we're gonna keep power from feeding out any of these circuits so unplugging this it's going to eliminate any problem in that circuit and unplugging that main light switch is going to eliminate any part of this in the circuit so I think that's the first thing we're gonna do it's simple it's easy so let's go ahead and move over to the vehicle and let's try doing that first alright guys so once again moving back into the vehicle and if you look over here this is where you'll find the main light switch you pull this you'll see that the headlights come on so what we're gonna do is we're going to try to gain access to the connector which I believe we can do by pulling this panel off so let me try to pop this panel off I think it's just a few clips to hold it on yep luckily I don't think there's any screws alright so now that we got this panel removed it's pretty simple to do now we can look underneath and I believe you can gain access to the main switch connectors right here so so I'm gonna go ahead and grab some pic tools and use those to open up these clips so that we can disconnect this connector alright so looking at that connector you'll see that we have two tabs on the side one here and one on the other side over here and I'm just gonna use this a long pick tool right here that has a little ninety degree on the end of it and I'm just gonna use that to pop the clip open on this side let me get in there I need to not try to look through the camera right there so I'm just gonna use it to get into here and I'm going to pry the clip open and pull down and what I'm gonna do is I'm going to use two of these tools one on the other side and I'm gonna pull this connector out okay so I'm probably both clips I'm gonna go ahead and pull it down just like that now we have our connector disconnecting all right so now that we have the headlight switch disconnected let's go ahead and move to the back of the vehicle and see if these lights are off and hopefully you guys can see that these lights are still illuminated okay so it's not a problem with the main light switch let's go ahead and move back underneath the dash here and I'm gonna disconnect the brake light switch which is located right here I'm gonna go ahead and disconnect it and let's go ahead and see if the lights are off man our lights are still on okay so what are we dealing with here so let's go ahead and move back to the wiring diagram and see what to do next alright so moving back over to the wiring diagram now we've already eliminated a possibility with the brake lighting system because we disconnected this brake light switch and our lights are still staying on and then also we eliminated a problem with the main light switch because we disconnected this but we still have power getting to the rear lamps now the thing is that we know that if we pull this 10 amp fuse here or excuse me 20 amp fuse which is fuse number 10 we know that if we pull this fuse the lights cut out but if we look at this diagram it looks like the only thing this fuse feeds is the main light switch but in fact if we go back up and pay a little closer attention to the diagram here you'll see the wire that comes out from the fuse is a dotted line now this dotted line means that it's open for other circuits to be connected to it so it's possible that there's other circuits that get fed by this 20 amp fuse also you'll see that there's a splice s 2:18 that splice indicates that this power feed also goes off to other circuits so I think the next step is to find the power distribution diagram and see what else gets fed by this fuse number 10 so let's go ahead and do that alright guys so here we are at the power distribution diagram now I've already gone ahead and located fuse number 10 which is a 20 amp fuse it's right here this is the fuse that whenever we pull it out the rear lamps go out so if you recall in the other diagram it shows that this feeds power to the main light switch again we've already tried disconnecting the main light switch and the lights still stay on so if we look at this diagram we'll see that there's actually a few other components that get fed by this fuse number 10 so if we follow the power out on this 10 and white wire we follow it over this way you'll see it goes to the vehicle security module now if we follow it down this way again you'll see it goes to the main light switch but if we follow it down this way you'll see it goes to the multifunction switch now this is really interesting because if you guys remember according to the diagram everything that powers up those rear lamps sends their power through the multifunction switch to light up those very lamps so in my mind seeing this power feed on pin 11 at the multifunction switch is a really good clue that we may actually have a problem somewhere within the multifunction switch because again whenever we remove fuse number 10 we cut power at pin 11 to this multifunction switch and those rear lights go out now I'm not really sure what this power feed is for it just shows that it goes to pin 11 at the multifunction switch it doesn't give us any internal circuitry as to what it does and if we look at the diagram that we had before it didn't show us a pin 11 so let me pull that diagram up real quick for the exterior lights again going back to this diagram I'm gonna zoom in on the multifunction switch and if we look around the multifunction switch which is this whole thing right here you'll see we have pin 1 pin 10 pin 6p and 9 pin 4 pin 3 pin 5 pin 2 and a pin 2 again we're not seeing a pin 11 so we're not seeing the circuitry that that fuse number 10 feeds into the multifunction switch so I think what I'm gonna do next is I'm probably gonna try to pull up some more wiring diagrams that are involving the multifunction switch maybe I can see how the internal circuitry works for how that power feed may be affecting or getting to these two wires right here again pin 2 and pin 5 are the two wires that go out to the rear lights so if we have a problem inside of this multifunction switch to where power from that 10 amp fuse or excuse me fuse number 10 is somehow being fed through pin 2 and pin 5 at all times then we might be able to say for certain that the problem is the multifunction switch so let me go ahead and dig through some diagrams and see what I come up with alright guys so I've located a diagram that shows the circuitry for pin 11 at the multifunction switch and I found it under the headlight wiring diagram so like I said the multifunction switch on this Ford it really is a multi-function switch I mean it does multiple things not only does it do the function for the turn signals it also does the function for the headlights for the high beams low beams and it also does the function for the wiper blades and the washers if I'm not mistaken so anyway it's looking at this diagram you'll see up here we have our fuse number 10 which is a 20 amp fuse that's in the central junction box again this is a fuse that when we pull it out those rare lamps go out so if we follow the power down it goes to pin 11 at the multifunction switch and you'll see inside of the multifunction switch we have these two switches one over here and one over here now this dotted line in the center represents that those two switches move together they're called a gang switch so whenever this one moves over here this one's also going to move over here so we have to remember that those two switches move together so if we look at this wiring diagram we'll see that this is for the circuitry for the headlamps now if we look in the normal position it's going to be pointing down at this low that I believe is for the low beam again if you look on this side you'll see low this is going to be in the normal state or neutral state and if you look when it's in the low position this power is not going anywhere it's just kind of there there's there's nothing connected to it but if you look on this side the power that comes from this main light switch so whenever this main light switch is closed it's going to send power through here and it's going to go through this switch here and in the low position the power is going to come out on this side right here and if we follow it down you'll see the power comes out and it gets spliced over to what looks like the daytime running light module so the DRL module is located right here it gets fed power through this spice right here and then if we follow the spice the other way you'll see that it goes through fuse 31 but if you follow it here it also goes over to fuse 25 so if he's power out through here and if he's power out through here so I'm gonna highlight both of those and you'll see that those power feeds go down to the headlights so if we look here we have the right headlamp and the left headlamp these are dual beam headlights so they're gonna have two filaments one for the high beam one for the low beam so again in this position this is a low beam so it's gonna be sending power through this filament here which is for the low beam and that's how we get the low beam function so if we go back up to the multifunction switch again looking at the gang switches here whenever we put these switches into the high position so we're gonna flick the switch over this way to the high position again this is not going to feed anything it's just kind of an open circuit on this side but if we look over here when we switch this part to the high position it's going to send power again from the main light switch down through here across to the high and if we follow this high right here it goes across out through this pin number 10 and it comes out on this gray and orange wire and it goes down to this fuse number 30 which is a 15 amp fuse and if we follow that down you'll see that it comes out on this light green and blue wire and if we follow the power coming out of there let me go ahead and deselect the other ones just so we don't get confused okay so if you follow that power feed coming out you'll see that it goes down to this filament on the left-hand lamp bulb and then if we follow it out this way you'll see it goes to the high beam filament of the right headlamp bulb so this is for the high beam function this is how the high beams get their power feed it's going to be through this fuse number 30 which is a 15 amp fuse again we follow it back up it comes from the multifunction switch and again it comes from the switch being in the high position so again when this winch has flipped over here to the high we're gonna get power that comes through the main light switch through this high contact here it's gonna go across over here and out through this wire and again this switch in the high position is just an open circuit it doesn't do anything so now if we look at the next function which is this path over here this is where this fuse comes into play this pin 11 so if we flick this switch over to the pass which I believe if I'm not mistaken is the momentary switch for the high beams so what I mean by that is whenever you're using the high beams and afford if you push the stock to the forward position it stays locked into place and the high beams stay on but if you pull the stock toward you or toward the steering wheel it's kind of a momentary switch so that you can flash your high beams at somebody I believe that's why it's called pass so if we follow this switch when it's in the past position you'll see that this switch over here when it moves over to the past position it also looks like it's got a little splice here but let's not pay attention to that we'll go back over here again we're gonna see it the switch when it's in the past position it's going to send power out through this brain orange wire we'll follow it down and we already know where the power for this fuse 30 that comes out here goes to it goes to the high beam circuit which is the high beam filament in both of the head lamp bulbs so essentially what that pin 11 is for is for the momentary flashing of the high beams so now when we think about it how is this pin 11 really tied in to anything that has to do with the rear tail lights because if we look at the circuitry it doesn't have anything to do with the rear tail lights the only lights that show up on this diagram or the front headlamps so at this point I'm not really sure how power from this pin 11 is getting out to the tail lights because again if you look at the other wiring diagrams again going back to the exterior lighting diagram if we look at this multifunction switch you'll see that this shows us the function for the turn signals so we have the left turn and the right turn signal again these are gang switches so whenever they flick they move together and that's what sends power out to the turn signals again pin 2 and pin 5 or where the power feeds for the rear tail lights go or excuse me come out through so again looking at the switch if you look up here you'll see this is the hazard switch function which I forgot to mention this multifunction switch also has the hazard switch on there so whenever you push that hazard switch you're moving these gang switches together and it's going to send power out to these pins pin two and five and of course the front lights - they also flash whenever you turn the hazard lights on so there's a lot of circuitry here that feeds pins two and five now the question of how the power from pin 11 for the high beam function is staying on and continuously feeding pin two and five I really don't know the answer to that and to be honest with you I don't know if we can really figure out the answer to that because there probably is no way to tell other than maybe opening up the multifunction switch maybe taking a look inside but then you know really what are you going to be able to determine and then really what are you going to do to repair it you're just gonna end up replacing the multifunction switch anyway so again if we look at this pin two in pin five again we know these go out to the rear taillights and if you look in this position in this state they both get their power through this connection right here this contact right here which is in an open position until this switch is closed here so somehow we're continuing to have a power feed on pin two and five alright so here we are at the steering column I already went ahead and removed the covers so we can gain access to the multifunction switch and the first thing I want to do is I want to disconnect these three connectors that are attached to the multifunction switch and I want to take a look at them because it is possible that we may have a burnt-up contact something like that that's causing the power to short and that may be what's causing our lights to stay on so let's go ahead and start by disconnecting this connector here go ahead and press the tab push out on the connector and actually it doesn't look like I can disconnect this because it's hitting this little piece right here let me go ahead and take the two screws out for the multifunction switch so that we can actually pull it off you alright guys so I went ahead and I disconnected all three connectors for the multifunction switch this is the multifunction switch here and if we look inside I really don't see any burnt contacts or any corrosion really so let's take a closer look at these connectors here and again I don't see any burned contacts or any corrosion these things look like they're in pretty good condition so I mean at this point it definitely looks like we have a problem with the multifunction switch again I'm really not sure how that pin 11 power feed is getting continuously fed to the rear tail light circuit but at this point I really don't think it's a question as to whether or not the problem is inside of this multifunction switch at this point I think we can say with confidence that this thing is going to need to get replaced so let me go ahead and get one on order and replace it alright guys so I've got the new part here it is a motor craft unit you look it's part number is now this unit was not cheap I think retail it's about $285 for this thing so again you really want to be sure that this is gonna fix your problem so I think what I want to do before we even bolt this thing in is I just want to connect the connectors and see if our lights go out so let's go ahead and do that all right so we have all three connectors plugged in now for the moment of truth let's go ahead and move to the back of the vehicle and let's see if the taillights are wrong not at all what I was expecting our lights are still on okay that sucks but what does that mean that means I made a bad call okay so I put the multifunction switch in the new switch and we still have a problem okay guys so I know I'm not going crazy I'm pretty sure I might have left something out now it's just time to figure out what I left out so what I went ahead and I did is I just put the old switch back on again it's not bolted up but what I wanted to show you guys was the connector where pin 11 is located so we look at this connector here this is the tan and white wire which is pin 11 that's gonna be the power feed that comes from fuse number 10 and again if you guys recall fuse number 10 whenever we remove it the lights go out so I think the first thing I want to try to do is I just want to disconnect this connector here and I want to see if the lights go out so actually I have my brother he's here to help me today he's at the back of the vehicle he's got his own camera and he's gonna be filming back there I'm gonna show you guys while I disconnected here and he's gonna tell me what's going on back there so let me go ahead and disconnect this what happened driver sat out the driver side is out yep just the driver side yes okay well that's weird because pin 11 is the only power feed I don't know why it's only to one side let me try disconnecting the next one which is this one right here I believe this is just for the hazard switch but just go ahead and disconnect it anyway anything happen cuz you're still on okay so nothing happened with that I'm gonna disconnect this last connector hey happen passenger off passenger hi driver so both of the lights are out now yes okay what happens if I just plug this one back in this is the one that had the pin 11 so I'm gonna connect this what happened nothing okay so nothing happens when that's connected when both of them are connected look I push the hazard switch passes you're on okay yeah what what's on right now both lights okay so when both connectors are connected both lights are on when I disconnect this connector one of the lights goes out which light went out driver okay so the driver side light goes out when I disconnect this I don't know how that's gonna help us but let's go ahead and take this information back to the wiring diagram and see what we can figure out all right guys so before I go to the wiring diagram I wanted to try something real quick so what I went ahead and I did is I remove the taillight lenses the housings as you can see we have them both unbolted or unscrewed from the vehicle and I went ahead and I popped out the light bulbs you can see they're both illuminated now what I wanted to do is I wanted to verify where the power feed was coming from the power source for these light bulbs so what I'm going to do is I'm going to back probe the connector let me set the tripod up here all right so what I have is my power probe here and I have a back probing tool and what I'm going to do is I'm going to back probe the connector because if you recall these bulbs have two filaments one filament is for the stop light and the other filament is for the tail lamp so if we look at the wire colors I know it may be difficult to tell but we have the brown wire and the our wire is the power feed that comes from the main light switch which is also known as the head light switch so what we're gonna do is we're gonna back probe this brown wire and we're gonna see if the power is coming from that circuit and then after that we're gonna check the orange and blue wire because that orange and blue wire is the power feed that comes from the multifunction switch so right now we're on the brown wire that comes from the headlight switch I'm gonna go ahead and touch it with the power probe and as you can see we don't have power I'm showing a ground on that circuit so let's move over to the orange and blue wire which is the power feed that comes from the multifunction switch and see what we got there as you can see we have system voltage which the battery is kind of low it's about eleven point one volts it's actually not dinging so it's kind of a low voltage let me disconnect the connector here real quick all right so if I touch it now it should be as you can see we are showing system voltage is 12 volts but it's kind of a weak voltage so there's some resistance in there because as you can see the power probe when it's a nice strong 12 volt source it'll continuously show a red dot here but in this case you can see it's kind of coming and going but we're still showing 12 volts which is system voltage so now that we've verified that on this side I just want to verify that on the other side I'm gonna plug this back in and then we're gonna go to the driver side and check for the same thing okay so we're here on the driver side I'm going to back probe the brown wire again that's the wire coming from the main light switch I'm going to go ahead and touch it with the power probe we're shelling the ground there so there's no power there so let's go ahead and check the other wire and on this side the wire color is actually orange and green or green and orange so let's go ahead and back probe this one I'm going to touch it with the power probe and hopefully that shows up on the camera but we have system voltage there and again it looks like it's a pretty weak voltage got some high resistance in the circuit but it is enough to light this light bulb so now we know that our problem is not with the circuit on the brown wire our problem is a circuit on the green and orange wire and on the other side the blue and orange wire and those two wires come from the multifunction switch so now that we've verified that let's go ahead and move back to the wiring diagram and see what we can figure out alright guys so once again we're back at the wiring diagram now if you guys are following along what we just verified by checking at the rear lights is that our power feed that's keeping these lights on is coming from the multifunction switch so again we have this orange and light blue wire that comes out on pin five that feeds the tail light for the passenger side and if you look over here this light green and orange wire that comes out of pin number two that feeds the driver side tail light now the interesting thing about this is that if you look closely at this pin two and pin five are actually on two separate connectors so if we look at pin 2 this is actually on the C 2 O 2 B connector let me zoom into that so you guys can see it a little bit better alright so hopefully that showing up a little better again if you look at pin 2 this is gonna be the power feed that comes out of the multifunction switch and it feeds the rear driver side taillight and again it's on connector C 2 O 2 B now if you look at pin 5 this is gonna be the power feed once again the feeds the passenger side taillight and if you look over here it's got this dotted line right here that's connecting it to pin 3 that dotted line just means that pin 5 and pin 3 are on the same connector and that connector is C 2 O 2 a so we can designate this as connector a and connector B so once again pin - on connector B is going to be for the driver side taillight and pin five on connector a is going to be for the passenger side taillight now that's real important to note because if you guys recall when I try to unplug the connectors on the back of the multifunction switch we noticed that when we disconnected connector B which is pin two for the driver side this connector B is also housing pin eleven which is our tan and white wire if you guys recall our tan and white wire let me pull up the other diagram for the headlights our tan and white wire is the wire that goes to pin 11 and that's going to be that fuse number 10 which is a 20 amp fuse the again whenever we remove this fuse those lights go away so if you look at pin 11 and if you follow again this dotted line that's right here it that dotted line is just saying that this pin 11 and this pin 9 are both on the same connector and that connector right here is connect our c 2o 2 B so again connector B as we're going to be calling it is where the pin 11 with the tan and white wire and the pin number 2 for the light green and orange wire are located let me take you back to the vehicle and show you that alright guys so once again taking you inside the vehicle what we're looking at is the back of the multifunction switch and as you can see we have a total of 3 connectors but the two connectors that we're concerned with is going to be this connector here which is C 2 O 2 B and this is going to be connector C 2 O 2 a we're just going to call them connector B and connector a once again connector B is where we'll find the tan and white wire which is located right here hopefully you guys can see it this is the tan and white wire and if you look at the plastic let me see if I can zoom in on that all right so I don't know if you guys can see that or not but on the plastic you'll see that it's actually designated or labeled pin 11 so this is pin 11 you'll see if we start over here 7 8 9 10 11 pin 11 is going to be the tan and white wire this is the power feed that comes from fuse number 10 and then if we flip it around here you'll see this is pin number 2 right here let me flip it around this is plan number two here and it's going to be our green and orange wire this is the wire that goes to the rear taillight on the driver's side so if you guys recall whenever we disconnected this I disconnected just this connector here and the only thing that happened was that the light on the driver's side went out the light on the passenger side was still on now that's a little odd considering that we were under the impression that the power feed from this tan and white wire was keeping both lights on but whenever we disconnect this we're eliminating the tan and white wire altogether and we still have power to the passenger side light and of course when I disconnect the other connector both lights go out so this connector here houses pin number five which is the wire that goes back to the passenger side taillight and if we look at pin number five here let me see if I can find it let me just go ahead and pull this out okay this one's a little more difficult to see but it's gonna be pin number five which is our orange and blue wire and again this is where the power comes out of the multifunction switch and goes to the rear passenger side taillight so what I can tell you right now judging by the unplug a test that we did is that the power feed or the power source that we're dealing with is not the power source on this tan and white wire because once again if we just connect the tan and white wire which is connector B I'm gonna reconnect it and let's go to the back of the vehicle all right so I move into the back of the vehicle you can see neither one of the lights are on now if we connect connector A which is the other connector I'm going to go ahead and connect it now let's move back to the rear of the vehicle you'll see that both of our lights are on and again like we did before if I disconnect connector B this light goes away so we know that whatever is keeping these lights on has to be a power source on that connector a so I guess what I want to do now going back to the multifunction switch is I want to go to this connector a-and I want to see which one of these wires has a continuous power even when the ignition is off so that's what we're gonna do next I'm gonna go ahead and get the back probe tool we're gonna get the power probe and we're gonna see where we have power all right so I've got my back probe right here and I'm gonna go ahead and start back probing these wires and we'll start with the pin number one here which is this blue wire I've got my power probe here I'm gonna go ahead and touch it we're showing a ground there's no power there let's move over to pin number two this green and white wire you touch it with the power probe no power there it's a ground let's go to pin number three which is a white and blue wire we're showing the same thing no voltage now moving over to at number four which is this green wire and we are showing power there now let's go ahead and move over to pin number five this is the wire that goes to the tail light on the passenger side touch it again we're showing a ground so we know when this is disconnected there's no power source going through there then we're gonna go to pin number six which is this green and red wire touch it with power probe we have power on hit number six which is a green and red wire now this is pin number nine which is an orange and yellow wire let's touch it no voltage and finally pin number 10 which is a white and red wire so I'm going to touch it there's no voltage there so what we found is that we have two wires that have a continuous voltage again we have pin number six which is this green and red wire and then we have pin number four which is this green wire here so the next thing I want to do is I want to see which one of these loses their voltage feed whenever I disconnect or remove fuse number 10 so I'm gonna go ahead and reach under the dash and I'm gonna pull out fuse number 10 all right guys so I went ahead and I remove a fuse number 10 now we're gonna go ahead and use the power probe and check pin four as you can see we lost our voltage feed there now just to double-check we'll go ahead and check pin number six over here and we still have our voltage feed there so it's normal to see 12 volts there but as soon as we remove the fuse on this pin number four the green wire we lost our voltage so now what we need to do is we need to back trace this figure out where this power source comes from and what we need to do is go back to the wiring diagram see if we can figure that out all right so moving back over to the wiring diagram i've already located pin number 4 which is a light green wire right over here and let me go ahead and highlight it if we look at this pin number 4 you'll see this light green wire if we follow it back over this way it goes off into a splice now we've already kind of been over this wiring diagram so let's follow it back up here I'm going to follow it back through this fuse right here which is a fuse 39 in the central junction box and then if we follow it up again there's another splice if we follow it back this way you'll see that it goes to the brake light switch now we've already tried removing this brake line switch so we know that our problem is not coming from here so now the thing is this circuit actually spreads out to a lot of different places so again if we follow it up this way you'll see that goes to the powertrain control module if you follow the splice over this way you'll see it goes to the ABS control module if you follow it over this way it goes to the brake shift interlock and again these are power feeds that are supposed to be coming from this brake light switch so if we follow it down this way we have this fuse 39 again it's a 10 amp fuse it's located in the central junction box and if we follow that power feed down this way again it goes over to the multifunction switch at pin 4 which is where we're seeing power when we shouldn't be but then if we follow the splice down this way you'll see it goes to the trailer electronic brake control connector so there's one place we could look then if we follow it this way you'll see it goes to some type of resistor I'm not really sure what this resistor is used for or why it's in a circuit but it's a resistor that's attached to a ground now if we look over this way we follow it down here you'll see that it goes to the center high Mount stop lamp and of course it's just got a ground on the other side so this is power feed for that high mounted stop lamp now the thing about this is if we look at this we can pretty much kind of split it into two separate parts of the circuit if we look at this fuse here we can basically separate this part of the circuit and this part of the circuit so I think the first thing we're gonna want to do is remove this fuse because if we remove this views and we see that we still have power here we can eliminate this whole part of the circuit so I think that's the next best step to do let's go ahead and move back to the vehicle and pull that fuse out alright guys to move him back to the fuse box first thing I went ahead and did was I reinstalled a fuse number 10 which is this 20 amp fuse here and now we're gonna go ahead and pull fuse 39 which is this fuse right here so I'm gonna go ahead and pull it with a pair of pliers and we have our fuse out now let's go ahead and see if we still have power on pin 4 at the multifunction switch alright guys so we're back at the connector here and I've got the back probe already installed on pin number 4 which is our green wire I'm gonna go ahead and touch it with the power probe yeah we don't have any power here anymore I'm gonna go ahead and reach underneath and I'm going to reinstall fuse number 39 and we're gonna see if we get power back ok so I went ahead and reinstalled fuse 39 let's go ahead and check it again and we have system voltage okay what does that tell us let's move back to the wiring diagram okay so once again we're back at the wiring diagram now we went ahead and removed this fuse 39 which is his tant fuse and whenever we remove this fuse we lost power at pin four at the multifunction switch what does that tell us basically what that tells us is that more than likely the problem we have in the circuit is somewhere on this side of the circuit not down here so we can go ahead and deselect everything down here and just worry about whatever's up here now looking at the diagram and the components that are involved here the question comes up is how does fuse number 10 that's right here come into play because if you guys recall whenever we remove fuse 10 which apparently is a totally different circuit we lose power to this pin 4 which is getting its power feed from one of these components are somewhere in the wiring harness so as far as the possibilities go I think it's possible we could have a short to power somewhere in the wiring harness that's a good possibility we could also have maybe one of these components I mean it is to me highly unlikely that one of these components is sending out a power or a voltage on the circuit because if you think about it neither one of these components are designed to do that I mean if you think about the powertrain control module right here I mean the powertrain control module just wants to see the voltage feed here to know that you're pressing the brake pedal the same thing with the ABS control module it's just watching the voltage on this pin right here waiting for you to press the brake pedal so it knows when you're pushing the brake pedal then again the same thing for the brake shift interlock the brake shift interlock is waiting for you to press the brake pedal in order to release the shifter lock and again we've already gone over the fuse number Tenth Circuit and we know that it does not direct tied to any of these components here this fuse we know feeds the main light switch it feeds the multifunction switch for the headlights or for the high beam so when I look at this diagram I really don't see any tie from this circuit to any of these components so again if you ask me I think we're dealing with the wiring problem here more than likely we have a short to power somewhere where power from this fuse number 10 is shorting to the circuit here for the brake light switch now as far as where to start looking I mean we could try to figure out where the wiring harness is run we can also look at these splices of course we have this splice here which is s 2 2 4 and then we have the splice over here which is s 2 18 we can try to figure out where they're located in the wiring harness we can also see here that this splice it says that it's located in the window regulator relay switch harness near the breakout to C 237 so we could try to figure out where the wiring harness for this runs and maybe we'll find that somewhere along the line we have a short to power here so hopefully that makes sense to you guys hopefully you're following along and hopefully we can figure out what's wrong with this vehicle all right guys so it's getting pretty late here I got to figure out what's going on because it's just about time to go home so let me show you what my plan of attack is here again I wanted to find the wiring harness that both of these wires run through and what I did was I went to the fuse box if you look at this fuse box on the back side you'll see the wiring harness that comes out of the fuse box and so what I did was I followed that wiring harness up let me see if I can get you guys a visual so if we follow that wiring harness up you'll see it comes up and around see if I can focus in on that that harness goes up and around and it comes down through here I know it's really difficult to tell but this is the wiring harness here right here and so what I'm going to do is I'm basically going to use my back probe that I have connected to the pen for here on the green wire and I'm going to take my power probe and I'm going to use this little jumper wire here so I'm going to plug this into the back probe here then I'm going to take my power probe and going to use the alligator clip to attach to the end of the power probe and of course we have a short to power so we know that when we attach this alligator clip this power probe is going to ding all right so now that I have the alligator clip attached to the end of the power probe so you can see we have system voltage I'm gonna push this little button that's going to turn the sound on and you'll hear it beeping that's an indication that we have power or short to power I know that sound is really annoying but what we're gonna do is we're gonna use that sound as a guide so I'm gonna move down here and I'm gonna start moving the wiring harness and we're gonna see if we can get that sound to go away so let's go ahead and move underneath here and let's start moving the wiring harness I'll start by moving the harness here and hopefully you guys can hear that in the background it's a really ugly dinging noise and hopefully we get lucky and see if we can find our short to power so far we're not having any luck I mean go behind the fuse box here I mean shoot it may even be possible that our problem is in the fuse box but let's just keep checking here is it just me or does that wire it look like hold on a second what is that you see if I can focus move this out of the way you guys see that it's not like a bare wire right here yeah almost looks like this wire got cooked what is that it looks like this melted or got really hot or something sorry guys I know that beeping sound is really annoying but hopefully you guys can see this bare wire right here it looks like it got really hot and might have burned off the insulation right not really sure but I mean is that where our problem is we get a little closer in there hopefully you guys can see can you guys see this it's a it's a tan and white wire and it's kind of stuck to this wire right here and this wire it looks like it used to be a certain color I really can't tell but they're kind of looked like they're melted together so let me try to take something like this pig tool here I'm going to try to separate those two wires I kind of melted together sorry guys I know trying to do this with one hand and hold the camera at the same time okay the wires are separated now no maybe up here well this all seems like it's kind of melted together let me just try to separate these wires yup these wires look like they're melted together it's gonna try to separate them and I actually hear some relays clicking when I do that check that out we just separated those wires and look at this wire here sorry guys I keep hitting the camera the camera is really close in here look at this green wire here alright guys I don't know if you guys can see this but these wires are all kind of melted together I'm trying to do my best I can to separate them I know that dinging is probably really annoying but look at that these wires are melted together and you can see we've exposed some of the wiring there focus in on that yeah you can see that the wiring is exposed there it's trying to separate these wires split them apart see if we can get this short the power to go away ah [Music] come on just listen for that dinging noise or that beeping noise see if it goes away you know what just looking at the color of these two wires looks like this is a green wire and this is our tan and white wire that may be where our problem is let me try to separate these two well now these two are married together there's no divorce happening here we're gonna have to force it come on yeah alright guys I really need two hands to do this let me try to set the camera down I'm a backup light just ran out of batteries I'm gonna try to hold the camera okay so I just peeled back some more of this tape and did you hear that [Laughter] okay I just moved this and the beeping noise went away so let me try to move it again our beeping noise is back I'm gonna move it again there goes our beeping noise I'm gonna move it again right there so definitely our short two powers here let me continue trying to separate these wires alright guys so now that I'm gonna be wiring harness opened up and separated you can see the extent of the damage if it happened here there's still some wires up here that are melted together that I'm gonna need to separate but it's pretty obvious that something happened here something may have shorted something caused a lot of heat to happen here to where these wires melted together now we know we're gonna have to repair this harness so basically I'm going to need to cut the harness from here to down there and then I'm going to need to rewire all of this but the question still comes to mind is why did this happen in the first place so it's possible that even after we repaired this harness we may still continue to have a problem now looking at this thing of course we had this wire right here which was the one that was completely bare and when I peeled it up or here you can see that it's actually I believe a brown wire so this wire looks to me like it's the one that got the hottest so because it melted all of its own insulation on so it's probably a good possibility that this wire here is where our short is coming from and like I said I believe it's a brown wire I'm gonna follow it to the connector and I guess I'm gonna try to see what circuit it leads to and maybe we can figure out why this happened to begin with anyways guys at this point I'm going to end the video off it's late it's after closing time I'm ready to go home it's been a long day so at this point we figured out where our problem is now we actually have a whole nother problem that we need to figure out and solve before we can actually repair the harness because like I said we don't want to repair the harness and then it had the same problem again so I think what I'm gonna end up doing is continuing that in a second part of the video so this will be part one as soon as I figure out what's going on with the other problem then I'll post that in a part two so anyways I hope you guys enjoyed the video I hope you found it useful I hope you found it informational if you did make sure to give it a thumbs up if you haven't done so already please subscribe to the channel make sure you hit that notification bell and I'll see you guys the next one thanks [Music]

Channel: ADVANCED LEVEL AUTO

Views: 21,855

Rating: 4.9235363 out of 5

Keywords: F150, F250, F350, F450, E150, E250, E350, ELECTRICAL PROBLEMS, FORD PROBLEMS, brake light switch, headlight switch, test light, electrical, electrical wiring, electrical engineering, electrical engineering basics, diagnostics

Id: wVNjwwcelP4

Length: 60min 15sec (3615 seconds)

Published: Sat Feb 15 2020