2008 Tahoe loss of electrical power while driving!!!!

[offroadmatt]

Having some major issues with my wifes 08 Tahoe. Sometimes while driving she looses all electrical power to everything related to the body: Instrument cluster, radio, HVAC controls, door locks, windows. But the engine stays running.
The other day it happened on the interstate. She drove it a couple miles to the next exit and pulled over. She turned the key off and then had no power to anything.
When I showed up I verified that all power was lost to everything. No lights, door controls, no power to ignition. Like the battery had been disconnected. I opened the hood and touched the positive cable and everything clicked back on.
So I brought it to my shop and cleaned both ends of the cable and checked it for any problems. None found.
Then it happened again the other day, only this time a touched the negative cable. Same thing everything turned back on. So I checked both its connections. No problems everything was tight and no corrosion.
I can not for the life of me figure out what the problem is.

While I was 4-wheeling it the other day the Navigation/Radio display turned off for a second and then came back on. Everything had power until I turned the key off. After I turned the key off everything lost power. Touched the fuse block above battery. Everything turned back on. Took it apart and cleaned all its connections. Which were not dirty. And reassembled. Had the same problem two drives later.

To keep this easy I will update this list with all possible remedy's:

1. Checked for corrosion on both ends of battery cables. Including smaller pig tails.

2. Checked all ends of battery cable hardware for tightness. All hardware tight.

3. Cleaned electrical connection and add Di-electric grease to Battery current sensor connection.

4. Pulled under hood electrical fuse box, cleaned all connections and added di-electric grease.

5. Replaced both battery terminals. Waiting for results.

 

[Jeff C]

After looking around on your behalf on the internet, there are similar stories out there. Seems like most of the signs eventually point to the computer.....

Sounds like it will be an expensive fix. Maybe find one in a scrap yard?

 

[offroadmatt]

I've also done some searching, actually a lot of searching. And like you the closest thing I can find is stuff pointing to the BCM (Body Control Module) $150 new. But I'm having a hard time believing its the BCM because how intermittent it is. In my experiences computers usually work or don't or quit working after they get warm and turn back on after cooling. But the other day I drove over 12 hours with only gas stops and had zero problems.

I'm thinking it has to be a loose wire somewhere. Maybe the power or ground wire for the BCM. Which I'm working on trying to find.

Plus a lot of the similar stories seem to relate to older vehicles, which is great but GM has added a ton of electronics since 99. Haven't found really anything for newer vehicles or anything for such a intermittent problem.

 

[NapaMatt]

i'll take a wild guess that is the power wire going to the BCM!!

i have seen a hand full do this.. just run a new wire..

 

[offroadmatt]

Knock on wood haven't had any problems since the battery terminal change. Thought I would throw a update out.

 

[rockin rmk]

There is GM bulliten for this promblem. Check the maxi fuse located on the firewall. Follow the positive cable from the battery. It is the little black box. remove the fuse and check for signs of arcing or corrosion. If there is replace the maxi fuse.. the pcm or bcm will not cause any of your promblems. It is a loss of power promblem.