Zx7cruz

Hello,
I'm new to this forum so thanks for having me. I recently bought an 07Tahoe and I'm having some weird issues. While driving the turn signals won't work, back windows won't go up or down, reverse lights don't turn on, and the brake lights stay on even though I'm not stepping on the brake pedal. After a while, the issues disappear but then return again later after I turn it on. Has anyone else had this problem? Any help would be greatly appreciated.

in2pro

Zx7cruz Welcome to the forum...

Does the vehicle have any added aftermarket accessories? (aftermarket alarm, remote start, audio equipment) if so check those connections.

Things that come to mind would be to check, the body to chassis ground cable(s) check the battery ground cable as well...

Check the brake lamp switch at the top of the brake pedal for the tail lights...

Re-seat the relays in the under hood power distribution center

check the ignition key switch for looseness, do you keep a lot of keys on the key ring? too much weight can wear the switch...

re-seat the connections at the lamp switch, check/reseat connection at turn signal lever..

Try removing battery power for a few minutes and see if everything clears up..

As a last possibility, it could be a body control module issue (BCM)

Zx7cruz

Hey In2pro,
Sorry I took so long to reply. The job has been killing me. Thanks for the reply. I'm leaning toward a bad BCM. I don't have any issues with any of the items you listed. Other symptoms are:
Tailgate won't open
Stabilitrack turns off by itself according to the dash
Hood open according to the dash
Rear windows do not go up or down
Rear door locks don't work
Wipers work, but not the intermittent part
As I mentioned before, all of these things correct themselves after about half an hour of driving, but they happen daily.
How much is the BCM and can I use a used one? Is it difficult to replace?

in2pro

The BCM is about $160 on GM Part Direct... however it will likely need re-programming for all the correct functions to work....Ebay may also have them listed..

I would reseat all of the BCM connections first, before replacing, if the BCM is bad its usually bad and not intermittent, not saying it couldn't be temp sensitive but the fact that is starts working correctly tells me that there is a bad connection somewhere....


Body Control Module Replacement


Preliminary Procedure
Remove the knee bolster. Refer to Knee Bolster Replacement

1
Body Control Module

Remove the BCM cover.
Disconnect the electrical connectors.
Press on the tabs to release the body control module.
If a replacement module is installed, program the module. Refer to Control Module References .

Zx7cruz

Thanks a bunch In2Pro. I'll try and reseat the connection like you've instructed before buying the replacement and I'll let you know how it turns out.

trainwreck91

curious...did this work? what was the outcome?

Zx7cruz

Actually, no. I looked at the BCM and there were a butt-load of connections that go to it. I called a mechanic friend of mine and he suggested I test out the fuses under the hood, circuit by circuit. Before I did that though, I looked at the fuse box inside the cabin on the driver's side panel and lo and behold there was a lil old 10 amp fuse labeled "BCM". It didn't look like it was popped but I replaced it anyway and the problems are gone. It's been 5 days now and there hasn't been a recurrence. If anyone can explain it, I sure would love to know how an unbroken fuse was causing all of these problems.

By the way, the dealer wanted $85 just to diagnose the problem, $350 for a new BCM, and $120 to program it, AND no guarantees! Gotta love em!

in2pro

There could be all kinds of things that could have caused the poor connection...

high humidity and corrosion
someone pulled the fuse and didn't seat it correctly or bent the connection
(could have been that way from the factory and just took time to deteriorate)
Some fuses have been known to pop and reconnect from the spatter...
Could have been a bad fuse....