I disagree. You're describing voltage spikes (either in-band, as in poor regulation or out-of-band as in ESD). Either is certainly a problem for sensitive equipment, and either would still be a factor to sensitive equipment after "main ground" was pulled. ESD is capable of jumping across huge air gaps to create its own ground... so if ESD were the concern over the BCM, GM would actually want to require ground straps from the BCM itself, and from the body (typically wrist or ankle, since those are the best escape points) of anyone coming in contact with it. They don't, and so that's either a clear indicator that ESD isn't the problem or they are clueless about ESD... as much as they've got me pissed off right now, I'm sure they understand ESD, and that the BCM is not especially sensitive to it.

Now, if it's in-band voltage spikes, then I point again to poor design. If you have a product that has very particular voltage requirements, then you design the power supply that feeds it to properly regulate that power... or you plan on seeing a lot of broken parts.

One more thing... the BCM does not operate on 5mv. Commonly voltage rails are 12v, 5v, 3.3v, and 2.7v. The amount of current required to get anything to operate at 0.005v would be immense.

 

I am suffering the same issue. Resetting the two blue/white connectors on the BCM by the passenger fuse box fixed it for one day. I am about ready to bypass the thing and wire it up to the lights in my radio or something. I also do not have lights in my door unlock buttons or my mirror controls.

 

I thought the same thing ^^^^. If there is a short in the dimmer, which all of the lighting "should run" through, that might be causing the problems. I'm trying to catch up on this situ...

 

Well after reading every post, I'm as lost as you guys. Interested to know if you ever found the problem.

 

Problem not solved. Local dealer's General Manager (whom I've been forced to build a slight relationship with to get anything done) told me, "I'm sure it's a problem in the system somewhere, but since you've messed with it, we aren't required to warranty it."

Thanks for being there for me, local GM dealership. Next time you're wondering why you never see my car in your bay, or my money in your parts register, try to not be too surprised.

 

Today, I found that if I juggled the wires running into the blue/white connector at the BCM (closest to the front of the car) The lights would work and flicker.
I am sure from the angle of the wires running into that connector one has pulled loose. May be Saturday before I can take it apart and check each connection. If not, I am going to wire a bypass or something.
Bob

 

Anyone know how to remove the connectors from the BCM?
It looks like you flip back the bale to release it, but I don't want to force it.
I am pretty sure several of the wires for the back lighting have broken at that point. What idiot designed it with a 90 degree bend at the point of connection, just waiting to break something.

Bob

 

One suggestion, probably already tried, I found that sometimes not all of the connectors go all the way to contact in a Molex type connector, you have to push them in individually? Like I said, probably already tried.

I am reminded of my 1969 Dodge Dart. No key any where near the car, depress brake pedal, turn on 4 way flasher....... listen to radio. Think it could be something as arcane as that weirdness? I assume that had to do with interconnected grounds, and most switches go to ground, but not all.

 

Chrysler...notorious for electrical situations....

 

OK, I disconnected the battery, released the blue/white BCM connector closest to the front of the car and re-seated it. All my dash lights and the heater control lights came back on. This lasted all of 2 days and now back to the flickering again. If you wiggle the wire harness to the same connector they flicker. Still no door lock and mirror control lights. Will try to disassemble the connector to see if there is a bad pin to wire connection. That or I have a broken wire somewhere in that harness. What a PITA

Bob