[The_rag__doll1]

Hey everyone, looking for some help in an SOS kind of fashion.

Short Backstory: last October I replaced all 6 cab mounts on my 4x4 04 silverado 1500 Z71. I forgot to disconnect my battery and fried the BMC when welding on the new mounts.

Following this incident I replaced the BCM with a reman. It ran fine for a week then went bad again. I figured it was a fluke so I had the shop send me a replacement. This new one went in fine but went into security shutdown so had to so to the dealership to have it cleared. This was six months ago. Since then it’s been completely fine and have had no symptoms or lights on the dash whatsoever.

That is until this afternoon when I went to leave work. (I’ve been having trouble with connection from terminals to posts on the battery due to corrosion.) I get in my truck and have no power so I get out, loosen hot wire bolt to relieve pressure on the posts, rub the terminal against the post a little and tighten it back up and it restores power asper usual. Except this time, all symptoms of my shot BCM have returned. (No power to windows or locks, no dome lights, constant power to the reverse camera(should only have power in reverse) and truck starts and immediately dies)

I’m at a loss as to what might be happening here. Obviously something is causing the BCM to fail but I have no clue where to even start diagnosing that because as I said I have no other symptoms or lights whatsoever.
Any and all help is appreciated!

 

[MotorEng91]

I would recommend to take the terminals fully off the battery and cleaned them with a wire brush to remove all corrosion. Also check the battery cables are not corroded internally by peeling back some insulation. If so replace those. It's possible the BCM has not failed but instead is not getting the proper voltage to function correctly.

 

[nealinator]

^^^ also remove and clean grounds. Its a good idea to also have the battery checked.

 

[davester3500]

If you welded and ran enough current through the truck to fry the bcm, perhaps there are other wires and or connectors that have problems...

 

[swathdiver]

I think there's something wrong with the posts on your battery, they are wreaking havoc on your electrical system and components. If the cables are corroded, replace them too.

 

[Walkers]

Replace your cables, even if they look good. Clean off the engine ground, as well as the body grounds under the drivers door. there is also a wire that is black with a white stripe coming out of the BCM, follow it to its termination and sand that down to bare metal.