Electrical Issue

Dogdays008

I have a 2005 Tahoe Z71 with 87,000 mile on it. It been babied. I'm having an electrical issue. My vanity lights on both side, my reading lights in the front and back and my rear view mirror doesn't have power (no temp or compass, not sure about the head light dimer) . Both reading lights will come on when I hit the remote or open the door then they will go off. The rear view mirrors On Star also works. All this occurred after I had the battery unhooked. I've checked all the fuses and they are good. Does anyone have a clue what could be going on? Could it be the Body Control Module?

thecardoc3

Has anyone connected a scan tool and tried to pull codes from ALL of the modules in the car? The vanity lights etc. get power from the BCM (Body Computer) on the inadvertent power supply circuit. Schematics unfortunately do a poor job of showing the power into the BCM that is used to supply that output. It seems unlikely that the BCM failed because of disconnecting the battery, but that cannot be ruled out. Can you identify if there are any other systems not working correctly?

How did you test the fuses? Be specific.

Here is a section of the BCM schematic showing the inadvertent power supply output.

Dogdays008

The garage door opener buttons just failed also. They are all up in the same place. To test the fuses I used one of those pin point testers where you hook the wire end to ground and the other end you put on each side of the fuse while it's still in the fuse box. All tested good. Sorry, I can't think of the name of the tool right this sec. LOL !!

thecardoc3

Lol, that would be a "Test Light" and that is the right way to check the fuses.

The Garage Door opener does NOT get power from the body computer like the vanity lights etc. It gets power from SEO fuse #1 in the under-hood fuse block. This is the same fuse that powers up the fog lights if equipped.

It is notable that every circuit you have mentioned share the same ground connection, G200 near the right hand "A" pillar. They don't take a direct path to get there and pass through some splices and connectors. Make sure you are using a good ground connection for your test light.

Dogdays008

Gotcha !!! Thanks for your help. I hope its something simple.