Is this a BCM failure?

[corsiman]

Hi guys,

So, a few weeks back, the battery in my 04 Tahoe died, and I had to jump it using my wife's Tahoe. (I typically never do that, but I was stuck) The next day, I took it in to have the rear brakes serviced. A day or 2 later, the issues below started.

1. While driving, all gauges will zero out as if I turned the truck off, and then come back on. Speedo and tac are unaffected.
2. Radio will turn off, then back on...as if you turned the truck off. Aftermarket deck with the Schoshe interface to keep the chimes. It's been in for over a year now.
3. While driving, the ABS and Parking Brake lights will come on (with chimes).
4. I get the Service 4WD message on the cluster. I had it last year, and replaced the selector button panel on the dash at that time.

That will happen separately or all at the same time, no rhyme or reason. Regardless of rain or shine, bumpy road or smooth. I had my battery and alternator checked, and everything tested ok. I've disconnected the battery cables for an hour. Took it back to the place that did the brakes, and everything is fine. I have a scanner, but there are no codes. I only have 2 keys on my ring with the fob, and the ignition cylinder feels tight. One place did a scan, and a historic code came up saying that it lost connection to the modules. All the while, the truck will run fine. I'm worried that I cooked the BCM while jumping it, but I figured I'd ask the experts first!

Thanks!

 

[about20ninj45]

Nah, sounds more like a loose ground somewhere

 

[W8TVI]

I second the loose ground. When I got my Yukon XL, the previous owner has put in a knife switch style battery cut-off, and I started having the same thing happen to me. I removed the switch, and everything was fine.

Double check all your cable connections/grounds.

 

[boomboom baker]

Could be a ground mine did the same thing back last year but it was my bcm

 

[Granprixfan]

The members suggesting the ground issue is consistent with the symptoms listed under 1, 2 & 3. Ground wire contact cleaning and sealing or even quality Big three (or more) wire replacement are a much cheaper fix than a BCM. Those are not cheap!
Speaking from experience...I had BCM go bad with non of the issues you have listed. The BCM failure researched here had all common symptoms like; open door or rear hatch or alarm going off for no reason. This is Not to say there other symptoms that a bad BCM would cause. I just have experienced those. Check all your grounds first.

The last symptom listed Sevice 4WD...Wait before taking action on this. Do grounds first. See if it goes away and returns or never goes away. I too had the service 4WD message since the day I bought it (9 years after it left the factory) I did the research here and replaced an electronic part inside the encoder motor that is mounted on the transfer case. The encoder motor switch simply is what those buttons on the dash "talk" to. You can replace the entire encoder motor as an assembly with the electronic switch part that resides inside as a unit or just the switch alone. But if the motor doesn't Ever move the transfer case gear select from 4Hi to 4Lo then you will definitely need the whole encoder motor assembly. Just search encoder motor here and on You tube

 

[corsiman]

Turns out you were all right. I work at a school with an auto tech program, and asked the teacher if they could check/clean all the easily accessible grounds. (they've probably saved me over a grand on parts and labor fees this year on truck repairs!) They started at the back, and sure enough, once they got to the engine bay, the ground that comes off the battery was loose on the frame and rattling around. They cleaned and tightened everything, and all the issues are gone...even the Service 4WD message.

Thanks for your help!!

 

[Crippin87]

I am having the EXACT same issues with mine! Thanks a lot, I am going to try and find the ground hopefully tomorrow. Where about is it on the frame?