Don't use a multimeter like this!

[Music] foreign [Music] hi everybody and welcome to a new episode of diagnose Dan today we're working on a 2013 Peugeot 107 which is the same car as sc2n C1 and a Toyota I go a very little popular city car here in Europe now this car is a crank no start it came from another shop and it drove the technicians at the auto shop completely crazy they replaced a lot of parts did a lot of measurements invested a lot of time but still a crank no start so let's see if we can diagnose this one together [Music] I talked to the other shops technician and he told me that this car has got an immobilizer problem there's no communication between the immobilizer and the engine computer now in all fairness this is quite a common problem on these vehicles and is normally caused by a broken wire between the engine computer and the immobilizer we even got some bulletins on this and ddtsb showing you exactly where usually those wire breaks occur now according to the other technician he double checked the wiring he did a continuity test and there's no broken wire so after that he decided to take a working immobilizer set so an end your computer and a mobilizer a ignition lock with antenna and key from another non-good vehicle placed it in this car but still a crank no start and still no communication between the immobilizer and the engine computer so in this video I want to take you through the steps that the technician took and see if maybe he missed something and hopefully we can figure out this mystery even replaced another module which in all fairness I have no idea where it's for but let's start out by confirming the customer complaint and let's see if this car is a crank no start and hopefully we can solve this mystery and get this little car running again now this is how I got the car the and your computer mounted with a tie wrap the wiring loom totally opened the battery has been out the fuse box has been out they removed the dash or partially removed the dash because the immobilizer is behind the dash they replaced or got rid of a connector that they thought was the problem that didn't fix it so a lot of time and effort already invested in this car but apparently it's still a crank no start now let's pretend all the other things that were done to the car were not done and let's start from scratch again and do our own diagnosis to see if the other technician possibly missed something now let's start off by confirming the customer complaints let's start it [Applause] and indeed it's a crank no start and let's try the other key and with the other key also a crank no starts or customer complaint confirmed now of course just like we expected this car has a crank no start now I quickly hooked up battery maintainer because the car was cranking a bit weak now in The Next Step let's read the fault codes and indeed there is a fault code stored the b2799 no communication with the immobilizer control module now this fault code is stored in the engine control module and of course if the engine control module is not communicating with the immobilizer it will never authorize the engine to run now over here we basically got the entire mobilizer system of this vehicle over here we've got the ignition lock with an antenna that reads the information of the chip inside this key now it will send that information to the immobilizer unit and when the immobilizer unit recognizes it's the right key it will send that information to the engine control module and it will then authorize the engine to run now the fault code we've got stored the b2799 is no communication between the immobilizer and the engine control module so that's basically the last part of the puzzle so in our diagnosis we're going to focus on the immobilizer and the engine control module I took a look at a wiring diagram and the engine control module and the immobilizer communicate on two wires it said green and a purple wire and since 99.9 percent of all times this fault code is being caused because of one of those two wires being broken I want to start out by checking those two wires although the other technique Edition already double checked it we're going to do it again and make sure he didn't miss anything now the communication wires are a purple wire the one over here and a green wire this one then they go into the wiring loom go behind the engine you can see they've already been checking it and it runs behind the engine here's the green wire and they go into the to a connector on the fuse box so there's the purple wire there's the green wire and they come out the other end of the connector then go into the car and finally they end up at the immobilizer control unit and these two pins right there so I removed the immobilizer unit and a back probe one of the two communication wires in this case the green wire and I hooked it up to my multimeter and I set my multimeter to continuity so right now it's set to continuity and it reads ol or open line a back probe the same green wire in the connector of the engine computer right here so when I touch that wire we can clearly hear the meter beep and we no longer have an open line so now we know for sure that the green wire isn't broken nav back probe the purple wire right next to it so let's hook up my probe to the purple wire right there and I also back probed that same purple wire in the connector right there so again the multimeter set to continuity open line right now let's touch the purple wire and the connector is disconnected equineer the meter beep again and it no longer is an open line so definitely not a broken wire so it looks that both communication wires have continuity so to communication wires between the immobilizer and the engine control module don't appear to be broken but still we've got no communication with the immobilizer so maybe we've got a broken immobilizer control unit so let's do a quick check I turned on the ignition and I plugged the module back in so let's go back to the scan tool and let's start out by reading the engine ECU one more time and let's read fault codes and there it is our b2799 no communication with the immobilizer control unit now let's try to read default codes in the immobilizer let's see if we can communicate and it looks like we can read fault codes and there are no fault codes stored in the immobilizer control unit so with the tester we can communicate with the immobilizer control unit but there's no communication between the immobilizer and the engine computer now the communication with the tester happens on a different wire than the communication between the immobilizer and the engine control module now since we can communicate with this control module it appears that powers and grounds to the module are just fine but I looked at a wiring diagram and this module has got three powers and one ground and just to be thorough and to make sure we don't miss anything I want to make sure we have all three powers and eventually check the ground so let's hook up my test light to a ground location and let's start with the first pin which is this one and that lights up so a power over there and then one next to it and we also have power on the second wire and then the Third and last power that's okay so let's check round next now the ground wire is a white wire with a black stripe on the corner right here so let's back probe it and let's use the power we've just confirmed to check our ground so let's hook up our test light between our non-good power and that ground wire it can see our test light lights up so three powers confirmed the ground confirmed and in all honesty I didn't expect anything else because we've got no fault code stored in the immobilizer and we can communicate with it but we had to be thorough now we can communicate with the engine control module and we can't communicate with the immobilizer control module but they can't communicate with one another now we check the two wires between them and they don't appear to be broken now I was thinking we back probe those wires so maybe there's a pin filament issue so in the next step I want to do a direct test to see if there's not too much play in the pins so they don't make a proper contact now let's start out by removing the immobilizer control unit and when you don't want to do a pin fitment or pin drag test look inside the module look at the size of the pins and try to find a similar size pin now we're going to concentrate on those two communication wires so the purple one over here and that seems to be just fine and the green one next to it that feels fine as well it's not loose so it's tight enough to make a contact now let's do the same thing at the engine control module now let's do exactly the same thing with the engine computer so let's start out with the purple wire that's the second one from the bottom one two and that's very tight that's perfect and then the one two three four five sixth at the top one two three four five six that's the green wire and that's just perfect as well now to be honest normally on these vehicles it's just a broken wire but this one is starting to become really interesting now the next step I want to do is not a part of any professional diagnostic procedure but since we've got them with the car and so easy I want to hook up the donor immobilizer and then your computer hook them up to the car I'm not going to hook up the ignition switch with the key so we might get a fault code for key not recognized or something but just for fun let's hook these up and see if anything changes foreign foreign so right now we hooked up a donor engine ECU and a donor immobilizer issue from a known good running vehicle now I didn't change the ignition lock so it's the wrong key for this set so we probably have gonna have a fault code for the key like key not recognized or something still a crank no start as you heard so let's read fault codes let's start out with the engine ECU and let's see read fault codes and we still got the b2799 no communication with the immobilizer control module again different engine control module different immobilizer control module so let's go back and let's read the immobilizer and let's read fault codes and as expected permanent fault identification of the ignition key so no difference with a donor engine ECU and immobilizer ECU except for defaulty key which was to be expected so what's going to be the next step guys I think it's time to bring out the scope guys to see what's actually going on on those two communication wires so I hooked up the original modules from the car again and the purple and the green wire are still back probed so let's hook up the scope to the green wire first the one at the front and there doesn't appear to be a signal we do have some kind of power let me switch off the ignition and switch it on again to see if anything changes and nothing seems to change now let's stick the other wire the purple wire and there there's nothing at all or something that appears to be a ground so let me switch on the or switch off the ignition and switch it on again to see if anything changes and also no chains over there so certainly no signals on those communication wires now on the yeah green wire we have something um that looks like a power or at least we've got 12 volts over there so I just want to do a simple test to make sure that this wire is not shorted to power so we should be able to pull down the signal using a test light so I'm going to hook one side of my test light up to battery negative I'm going to touch oops I'm going to touch that green wire and if it is shorter to power my test light should light up if it isn't we should pull down the power and we can so this is not a hard 12 volts now the other wire appeared to have zero volts or something like a ground so let's change my test light to battery positive and let's see if that wire is not shorter to ground if it is my test light should light up and just look at that I don't know but signals do not travel over a shorted wire this wire is fully shorted to ground and that explains why it can't communicate now let's check the same thing inside the car so I hooked up my test light to battery positive so when we touch ground the test light should light up now this purple wire is just connected between the immobilizer and the engine control module it shouldn't be connected to anything else now let's touch it with the test light and you can see how the test light lights up now it's not supposed to do that so let's do the same thing with the control modules disconnected so right now the purple wire isn't connected to anything it's a floating wire between this connector and the connector inside the car now again test light connected to battery positive so when I touch the ground the test light lights up and as you can see the test light lights up so although this purple wire shouldn't be connected to anything it's connected to ground now let's do the same inside the car nothing connected to the purple wire let's touch it with the test light and the test light lights up so somehow that purple wire is connected or shorted to ground now let me quickly show you something and hopefully we can all learn something here I beg probe that purple wire and I connected it to my meter now I set the meter to continuity and right now it shows open line now let's touch the purple wire the other side of the purple wire with the other lead and the meter starts to beep and it no longer shows open line so you might think there's nothing wrong with this wire now let me touch the negative terminal of the battery and again that meter starts to beep or let me touch that ground point over here and the meter starts to beep or let me touch a bolt on the engine right here and again the meter starts to beep so the question is is a continuity test the best way to test a wire and the answer is no it can get you into trouble and it's probably what prevented the technician that worked on this car to solve this issue now I decided to make a rather radical decision I decided to cut the purple and the green wire from the wiring harness although I don't think there's something wrong with the green wire but just to be 100 sure and don't worry after the diagnosis I will repair the wiring harness up to very high standards and in all fairness there's probably something wrong with the harness anyway so a wire needs to be replaced anyway at some point now I put a jumper wire directly to the immobilizer control unit in the car foreign so I totally bypassed the cars wiring harness now let's hook up the scope and see if we're getting any signals now let me start by checking the green wire over here and again we see the 12 volts let me turn on the ignition yeah and now we're definitely getting a signal and let's check the purple wire and there's a signal over there as well so we're inside the car wires off the immobilizer 2D and your control module are bypassed we know there are signals we've checked it with the scope so the moment of the truth let's start the car and it starts and it stalls again let me try a different key and it stalls again the symptoms definitely change let's try one more time so now it is a start stall so now we went from a crank no start to a start stalls but still no fix but I actually have seen this before when you have tampered with the Toyota immobilizer system and this basically is a rebranded Toyota iGo when you've tampered with it and we have tampered with it because there was a wire shorter to ground we installed different immobilizer control units we installed different engine control modules at some point we tried to start the engine with a key that didn't belong to the immobilizer so the system is pretty upset or must be pretty upset right now but when you've tempered with it or when you installed a new immobilizer control unit you need to do a realignment between the engine control module and the immobilizer now there's a procedure for that so let's do that procedure and hopefully after that the car will start so we need to do a relearn procedure for the immobilizer and we actually got that procedure covered in diagnosed and TSB or ddtsb it states that you need to connect pin 4 and 13 and DLC together for 45 minutes and then the system should be happy again so I connected pin 4 and 13 together with a jumper wire and you can actually see that the procedure started because all kinds of Lights start blinking on the instrument cluster now we should leave it like this for 45 minutes come back and hopefully after that the system is happy again and the car will run now the jumper cable has been in there for a little over 45 minutes so I think the system should be happy now so let's place your bets let's pull the cable out of there let's turn the ignition off start the car Moment of Truth after all this work just look at that all this time finally this car is running again awesome now it's great we finally have this engine running again now I was looking underneath the hood of this car and kind of following that purple wire to see if there's anything obviously wrong with it that I or the previous technician may be missed now I opened up my test light to the wire so we can see it's still shorter to ground I pulled it out of the harness so we can kind of follow it so it goes there behind the engine and it goes down over the gearbox comes back up and then it goes into this junction box into a connector in the fuse box and on the other side it comes out again and goes into the cabin off the car we can even see that somebody has been poking that wire now up until this point you can kind of follow it and Eyeball it and there doesn't seem to be anything wrong with it but when I was following that wire and kind of touching the harness I saw something blinking in the corner of my eye now Watch What Happens when I wiggled this connector you can see the short disappearing when I wiggle the connector so I'm pretty sure that the problem is somewhere in or near this connector in the junction box now personally I really enjoyed this one and hopefully we've all learned something like for instance that an ohm test or continuity test isn't always the best way to test a wire and sometimes like in this case it can get you into trouble now of course we're all very curious where the shorter ground is actually located on the car now I will call the customer and ask for permission if we are allowed to continue our diagnosis and find the actual short ground in some cases once they know what's wrong with the car they want to do the repairs themselves but if we're allowed to do it I will include some pictures at the end of this video now I really hope you enjoyed this video if you did please subscribe to my channel and when you hit the little bell you will get a notification each time I upload a new video and remember diagnose Dan fixed it again see you next time guys now of course I don't want to end this video without showing you guys the root cause of this issue so I decided to remove the battery and I hooked up some jumper cables so we can still see we've got a short to ground now with the battery out of the way we got way better access at the junction box and we can take a closer look at that connector now this is the purple immobilizer wire and next to it is a white wire what turns out to be a ground wire now look what happens when I pull that ground wire a little bit away from that purple immobilizer wire we can actually see that the short disappears now it's a little bit hard to see on camera but when we take a close-up look at that connector we can actually see that the pin of the purple wire has been bent open and it's touching the white round wire now I don't know why and I don't know when but somebody has been poking disconnector and this is what was causing all our issues now I talked to the technician at the other shop and he told me that this car has got an immobilizer you know [Music]

Channel: DiagnoseDan

Views: 199,267

Keywords: B2799, Toyota, Peugeot, citroen, immo, Topdon, multimeter, Autodoktoren, south main auto, pine hollow auto, scotty kilmer, rainman ray, immibilizer, fix, diagnostics, garage, workshop, scantool, learn

Id: xfohKS-HFGg

Length: 26min 18sec (1578 seconds)

Published: Tue Jan 10 2023