2008 GMC Acadia electrical issues

Ronald Owner/Technician North Carolina Posted   Latest   Edited  
Unsolved
Drivetrain
2008 GMC Acadia 3.6L (LY7) 6-spd (6T75) — 1GKEV33748J276886
No Turn Signals
Horn

I found water intrusion in the interior fuse block. It’s replaced with a new one. Now the radio turns off with drivers door opening. I still have no turn signal horn or no headlight dimmer. I can turn them off and on with scan tool. No emergency light. I’ve got a used BCM same part number. I also have a turn signal headlight dimmer switch new to install. I plan on pulling steering wheel next to check horn switch contacts. I can see where someone has had it apart. I know to voltage drop power and grounds at BCM, then leave battery unplugged while installing BCM. Can I use tiss2000 and my tech2 to program BCM? or get a subscription ? I may be needing to update cluster for battery drain? I have also had an issue with no data on scan tool for cluster or rear hatch. 

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Brad Diagnostician
Washington
Brad
 

You have to slow down brother and really say what is going on. I feel like I am reading a speed racer story. So we know we had water intrusion. And you replaced the IPBEC. Did you have green terminals, and if yes did you remedy that? Did you fix the water leak? If you can honk the horn with scan tool why in the world would you yank the wheel? Stand back, deep breath, cup of coffee and see…

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Ronald Owner/Technician
North Carolina
Ronald
   

I can only honk horn with scan tool, same with headlight dimmer. When I use the scan tool I can turn left or right turn signal on but it just turns turn lamps on the front and rear with not lamp flashing.

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Raymond Mobile Technician
Michigan
Raymond
 

I had a same issue with 2008 caddy CTS, turn signal, I was able to install a used BCM and re vin it with j 2534 autel flash thru device and subscription with ac delco SPS, the tis 2000 seems outdated I would use j2534 and SPS and replace and program BCM there change VIN # at that time

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Brad Diagnostician
Washington
Brad
 

So you'd chuck the BCM at it before looking at anything else?

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Raymond Mobile Technician
Michigan
Raymond
 

you can still do all your powers and ground checks, but even with the used BCM in my case before I even flashed it and changed the VIN thru SPS programming it was a relief to see the turn signals working, then I proceeded with the replace and program with a j 2534 , laptop thru ac delco SPS

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Ronald Owner/Technician
North Carolina
Ronald
 

My old laptops are junk and worthless. My new laptop is wind10. It’s a dell and very fast and powerful. I’ve got a pass through and the tech2. Which is easier to program this with? I’m thinking about getting a MDI.

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Raymond Mobile Technician
Michigan
Raymond
 

Yes mdi is the way to go if ur doing lots of Gm. So if u installed the used bcm and still no turn signals or flasher , I would look at troubleshooting like the flashers and follow it all the way through. I know for a fact that the turn signal and flashers should work programmed or not, meaning u don’t have to flash program the bcm to get them to work, also u have to keep in mind ur dealing with…

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Timothy Owner/Technician
Wisconsin
Timothy
 

Not correct about functionality without programming. Have done a bunch of new BCMs on these, and you get almost NO functions without it. Salvage is already ‘programmed’ so you'll have whatever the original flash had.

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Raymond Mobile Technician
Michigan
Raymond
 

I thought this was a salvage yard used bcm he was trying . Turn signals does not have to be set up or configured they r standard and should work plug and play if it was a bad bcm , I’m going off experience with a 2008 caddy Cts I had with no turn signals along its other issues I installed a used bcm and before I even flashed it thru sps they worked and flashed fine and hazards worked something I…

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Timothy Owner/Technician
Wisconsin
Timothy
 

That's what I said: a salvage BCM is ALREADY programmed, so you'll have some functionality. Usually not the case on a new one. Also, a CTS is a whole other thing. The systems are not the same as his.

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Bruce Owner/Technician
Texas
Bruce
 

Ronald, I know of no way to rewrite a VIN to a CAN GM vehicle on a used BCM without either using an EE Prom dump from the original or using the new I/O device with a subscription for the BCMs, if that BCM is even covered with I/O software. You can just plug the BCM in and see if any changes occur as the horn and turn signals are standard, other options can be different GM SPS will not…

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Ronald Owner/Technician
North Carolina
Ronald
 

I plugged it in. Only thing I got was control of the headlight switch to turn off and on. I’m leaning towards the turn signal switch it also has head light dimmer. Also was still no emergency flasher with used BCM. Is it possible for the old BCM just needed reprogrammed?

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Bruce Owner/Technician
Texas
Bruce
 

When you say old BCM, if you mean original, I doubt an update would help. You should be able to pull calibration files out of the origianl BCM, take a photo of them or write them down and go to : acdelcotds​.​com click on “Resources” along top of page and then go to TIS Calibration Information, enter your VIN then look for BCM and make a comparison of your actual cal files to the…

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Timothy Owner/Technician
Wisconsin
Timothy
 

If you look in the scanner, in the BCM PIDs, you'll see whether the BCM is actually ‘seeing’ the turn signal request from the switch, and the horn, etc. If not, you may be headed to the steering wheel, but much easier doing it through the scanner, or checking the input wiring at the BCM. I've had many of these that had blown fuses that fed the BCM power for the various circuits, far more common…

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Ronald Owner/Technician
North Carolina
Ronald
 

I’ve tried that. The cluster won’t communicate also the hatch module. I see hatch data in the horn and signal data. But both work. Hatch opens with touch release and cluster shows all functions. I’ll go try again after I’ve done the fuse block.

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Ronald Owner/Technician
North Carolina
Ronald
   

Ambient light sensor. I’m unplugging it now. See what that does. It is unplugged. Someone has been working on this. The air bag is out of place. The steering switch cover is out of place.

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Timothy Owner/Technician
Wisconsin
Timothy
 

I'm not too sure about what the cluster has to do with no turn signals or hazards. You can see the t/signal switch commands from the multi-function switch in the BCM PID list. Do they show activation? If so, then you need to trace the powers as I said before. If not, you need to go and see if the power for the switch is getting out of the BCM, and is being pulled to ground, which means the…

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Brad Diagnostician
Washington
Brad
 

And MAKE sure the terminals are good when changing the IPBEC!!!!!!!!! If it had water i guarantee some of those if not most are toast

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Ronald Owner/Technician
North Carolina
Ronald
 

In BCM data for exterior lights turn signals show inactive

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Timothy Owner/Technician
Wisconsin
Timothy
 

Okay, now we're getting somewhere. The BCM sends out a voltage to the switch, and the switch grounds it. Two wires, pins 15/16, at connector X1 on the BCM, should be voltage, that should be grounded when the switch is used. Voltage, that switches to ground and no activation seen by the BCM means the BCM is DOA. Grounds are G30⅓02 for turn signals and hazards. Voltage, but nothing changes when…

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