Diagnosing a BMW That’s Had the Parts Store Thrown at it

hey Andrew what you working on man hey what's going on brother got a fun one here got a 2007 BMW 328i with the n52 engine in it the client states that they have a crank no start condition um this client has definitely redefined throwing the parts cannon at one we've already figured out the issue with this car so we're going to go back through and show you our diagnostic process show you how we came to our conclusion so let's get into it all right so let's start off with the fun part in the notes the client let me know that uh he had all the old parts and all the modules and things that he replaced labeled for me in the trunk so let's uh let's see what we got here as we can see we've done a few footwell modules a DME AC control head which is interesting you'll see that in a little while we've got a yaw rate sensor he said he's put a couple of batteries in this car as well so let's let's get in where I started on this thing we've actually removed the affected relay from the circuit that we found to be the primary issue that way we can kind of walk through the steps with y'all and have the no start condition that he was exhibiting so let's get to the front here and dig in [Applause] so I started off obviously doing a code scan um we pulled codes up with the ISTA software hang on I want to give them give them all the pictures yet all right so we got the code scan went through here a lot of footwell module fault codes some messages missing exhausted battery Etc now I will mention that this battery was disconnected when I originally went out to the vehicle I reconnected the battery in order to push the car in the shop and attempt to start it we've got no DME fault codes after several times of cranking so we went back to the basics I mean what does an engine need to run you need compression fuel air and Spark so one quick test I like to do just to establish whether or not I've got spark is I'll just shoot some alternative fuel into the air box to see if the car attempts to start obviously it's not going to run like it should but just to give it some fuel to see if it's actually sparking now if I can uh if I can get my assistant in here to go ahead and crank this thing up assistant we're gonna add we'll show you it's got a no start right now go ahead sure would [Music] you gotta press the clutch for manual there's still a little in there try it again all right so we've got we've got a no start condition so we'll add alternative fuel into the intake all right so we see it it tries to start all our alternative fuel so that tells us we've got spark so all the all the coils are functioning the way they should so now we need to start looking at the fuel side of things um I've got a fuel pressure tester this is actually our fuel injector cleaner setup from Valvoline but I like it because I've got a gauge here I can do a fuel pressure test just like any fuel pressure tester and in the event but I don't have fuel pressure I can add alternative fuel to make the car run all right Sherwood if you wouldn't mind go ahead and crank it let's show them we've our fuel pressure gauge we're watching this one here we've got no fuel pressure on this vehicle so the beauty of this is now I can apply pressure pressurized fuel to the fuel rail to verify that the injectors are functioning the reason I'm going this route as opposed to scoping the injectors or anything like that is there's a ton of plastic covering that covers all the wires and it's an entire assembly of all the connectors so I've already got this hooked up it's quicker let's go ahead and add pressurized fuel 65 psi should be enough to make it start and turn this valve now we're pushing fuel all right professor and she's purring like a kitten all right thank you so that tells us crank sensor is good cam sensors are happy it's starting it's running we're getting fuel injector poles we're getting spark we're just missing fuel pressure so fuses [Music] probably could start there but on this particular vehicle it's very easy to get to the fuel pump so you just pop lift the rear seat and the fuel pump wires are right here so we've gained access to the fuel pump we're tapped into our powers and grounds now we're going to proceed with testing powers and grounds at our fuel pump all right we've got our eight channel ATS lab scope hooked up here just want to take a brief side note to show you proper ways of hooking a lab scope up number one whenever you're diagnosing a car maintainer we cannot stress this enough um you always want to hook your ground for your scope up to the battery Ground Terminal um you can show it's back here we're hooked up to the battery ground there all right so we got our battery ground hooked up we've got two channels tapped into the power and ground Supply going to the fuel pump yes we're piercing wires yes we're going to reseal them to prevent any water intrusion all right so we've got it pulled up here I just I like going to the stack scope setting because I can verify if those boxes are red that means we do not have a good connection if they're not red we're good to go we've got a good connection so we'll go into deep record here we're only watching channels one and two all right Professor can you give her a crank all right and as we can see here we're stuck on ground it is still trying to start because it's got a little pressure in the rail from our previous test but we can see we've got no power supply to that fuel pump [Music] all right so looking at our wiring diagram Let's uh [Music] let's see how this thing's controlled so as you can see here is our fuel pump we've got the two wires that we just tested they come from the fuel pump control module so luckily enough on this vehicle the fuel pump control module is really close so let's go to the fuel pump control module and see what we might be missing here all right so we're now hooked up to our fuel pump control module and the two wires that we're hooked up to are the red and black wire on pin one and the brown wire on pin two that's our main power and ground feeds for this fuel pump control module so if you look here you can see where we're tapped into the wires here that's our channel one is on our power channel two is on our ground so let's go back to the scope I'll always revert back to the stack scope just so I can verify I've got a quality connection measuring deeper cord all right we're flatlined at zero here all right Professor if you could give us a key cycle here as you can see here we're still flatlined at zero we've got no voltage what you're seeing here is actually the voltage drop of the vehicle cranking so the load of the engine is is changing that so we've still got no voltage here so if we come back to the wiring diagram obviously that module is not going to function if it doesn't have battery voltage getting to it our battery voltage is supplied by fuse number 68 oh no I'm sorry that's for the there our battery voltage is supplied by fuse 40 or fuse F 88 now the difference is is early production and late production I've already determined this is an early production and it is fuse F40 that we're testing here so let's go to the fuse box behind the glove box and check that fuse and relay all right so we're behind the glove box now at the fuse panel the fuse that we're going after is fuse F40 which is this Center fuse right here given that it's such a tight spot I'm going to hand the camera back to my cameraman and he's going to watch the lab scope while I touch that fuse and you can see the recordings I will mention so I will mention while I'm here like we said we we basically duplicated the symptom the car is fixed at this point I have removed this fuse and it goes in that location there all right so we're connected to the F40 fuse in the fuse box here and I'm going to have the professor go ahead and give us a starting cycle here all right we can see we're cranking but we have no voltage we're still out of ground state we should be seeing voltage that that fuse should be supplying voltage to the fuel pump control module so let's go take a look at the wiring diagram and see where the power comes to that fuse from a little side note in the process these tests can also be done with a test light or a multimeter anything of that nature at this point we're just testing powers and grounds we like them the lab scope because it can test powers and grounds just like those tools can plus it can do many other things so we go ahead and grab that first it's on and ready at all times around here so all right we've got the I'm trying to zoom in a little bit make it easier to see we've got the F40 fuse right here and it receives its power from the terminal 30g relay now I will say this is how we duplicated this no start condition is we have removed this relay but I'm going to show you how I tested and where I found an issue at that relay to send me down the the next PATH all right so we've got the relay that I showed that we have removed this is our terminal 30g relay if you want to look here at the wiring diagram so this is where our fuse that we just tested that has no power supply on it this is the relay that it comes from so just to explain the basic function of a four pin relay here you've got four pins obviously you've got a two large pins and two smaller pins so obviously the higher load of this circuit is going to be the fuel pump so these two large pins are going to be the pins that the voltage flows through to go to the fuel pump so during testing we found that we did have voltage on one side and of course we had a ground signal on the other side which is it finding a ground through the fuel pump control module testing of the control relay side of this relay we found that we had a ground but we were lacking power so most relays are all relays on the control side they're gonna have they're going to be ground or power controlled meaning another module or another relay is going to send a power or a ground to that energizing coil in order to close that switch to transfer that power or ground that it needs to transfer so in this particular case this is a a power side switched relay and we found that we are missing our power signal and in this diagram you can see it tells us to refer to the anti-theft system wiring diagram so let's go to that wiring diagram and Trace that wire and see where it goes all right so here's our Anti-Theft wiring diagram here's our terminal 30g relay here's that same red wire from that energizing coil and that is a direct connection to this module here and we've got the car access system control module or cast module that's located underneath the the left side of the dash so what I did in this situation is I gained access to this module and I back probed that red wire or the control wire for the relay and performed a start cycle we still had no voltage control coming out of this module so I performed testing on the powers and grounds we had two powers and two ground circuits that feed this module load tested those they all load test okay and then I tested the terminal 15 which is our ignition circuit to this module and it is receiving the signal that the ignition switch is turned on so it seemed like the module was happy and everything seemed to be working so something wasn't adding up so in that that situation I was like visual inspection so let's let's pull the connector off and lo and behold when I pull the connector off we've got a bent pin on that number one location for the power supply for that side of the relay so we removed this we actually had to remove the the module out of the housing in order to get the pin because it not only bent the pin it pushed it in a little bit so I was able to finessely straighten that pin out and we got the connector to engage properly and now the circuit Comes Alive we put the relay in the car starts and runs let's start the car let's start the car so we're going to reinstall our terminal 30g relay here and we'll come out back up here to our fuel pressure gauge professors already helping me out bleeding the pressure off all right so we're paying attention to the gauge on the left here this this gauge is the pressure that's in this tank I've got this valve shut so this is our our pressure gauge is tapped into the fuel rail as we did before so we see there initially key cycle we've got fuel pressure go ahead professor and boom look at that so somewhere in the process of replacement of modules or somebody had that module out at some point in time and when they went to go reconnect that connector they just didn't have it straight enough or somehow got it cock-eyed to wear it bent that pan over and that was his whole issue with this no start condition now there were a couple other issues on this car um I haven't gone further than this point right here so I am going to go back and and look at uh ISTA and see if we now have communication with our air conditioning control module because we did not have communication with that module before didn't really pursue that too much because it's an air-conditioned control module where the car is not starting um definitely can't be ruled out in every situation but it wasn't really my starting point especially once I finally had no fuel pressure so let's uh let's hook up the ISTA and we're going to do a module scan on this and this this is going to be live I've not done this yet so let's see we've got one thing for everybody to remember here is this car came in most people would pop that trunk and would just be like oh gosh you know who knows when you're getting a car in and you're going to work on I don't care if it comes in with 15 models in the trunk or nobody's ever touched it follow the data don't worry about what somebody's done don't worry about what's been replaced if you follow the data you'll get to the answer now there may be more than one path that you have to go down because obviously in this case things have changed that pin didn't magically Bend itself right so at some point while this man was working on it trying to fix his car the pin got bent so possibly something else that he did fix the car but because the pin got bent during the process he didn't know it so now we've got to go in again Andrew's going to continue following the data why do we not have any communication with this module I mean it was a module that was replaced so now we're gonna go down that path and come up with the answer on that too so all right all right so we've got the vehicle hooked up to ISTA we have done a full vehicle identification we've got all of our data here this is the home screen of of esta for those who don't know ISTA is the factory software for BMW and esta stands for integrated service technical application all right so let's got our van Information Program levels and things but what I really want to see is our control unit tree let's compare it it's what we had previously as we can see here everybody's green is good green is go everybody's happy previously the ihka module right here which is the climate control module was yellow so if you look in the bottom right hand corner here this Legend shows you green as a control unit is responsive yellow is control unit is unresponsive so previously our air conditioning control module was not communicating now we've got communication we never diagnosed or fixed anything particularly on that circuit but if we went back and looked at some wiring diagrams I can almost guarantee you that that 30g relay supplies power to a fuse that transfers power to that module in order for that module to function so now that we've corrected that bent pin the 30g terminal is now activated and happy the module is awake it's functioning as it should so we killed two birds with one stone and that in that situation um he did mention that he's been having a battery drain the battery dies periodically so we're going to go into that and verify that we don't have a parasitic draw if it does we might have another video on this car we'll see but this is another perfect example of why we test don't guess hey guys if you like this video give us a thumbs up subscribe to the channel and ring the bell so you can get notified for any of our future videos as always we appreciate you and we'll see you next time

Channel: Royalty Auto Service

Views: 19,625

Keywords: Diagnosing a car, BMW, Using a scope, Car diagnostics, Working on bmw, Mechanic, Technician, Auto repair near me, BMW mechanic

Id: P1WHgI6RN5I

Length: 19min 52sec (1192 seconds)

Published: Sun Mar 26 2023