I wanted to add, when inspecting, checking loose connections, bent pins , low voltage, many times the intermittent electricical problem is inadvertently resolved.

 

Sorry Cat Man. I'm not exactly sure what you are looking for. A discussion on something like is going to include some troubleshooting ideas. That's the nature of a forum like this.

That said one person's dealer solution of a bad BCM is anecdotal at best. Yes it's possible but I wonder how common it is? On one GM truck forum I'm on people have had parasitic drains caused by things from a bad hood closure sensor to a stereo system that looked like it was off but was draining the battery. I had it happen with an under hood light once.

You're saying this is intermittent but how often?

 

So videos on YouTube for testing for drainage
https://www.google.ca/search?q=how+t...&client=safari

 

Wait. If it's that easy, I vote NO.

Keep the thread going...

 

If it is intermittent you do the diagnostic when it is happening. Or, do the diagnostic while wiggling wires.
I don't know of a way a layman could run diagnostics on a diagnostic computer, maybe a Tech2 has a program for that.
In my experience, just one function of a computer failing is rare.

 

I know... one should not "assume", but... Just for the sake of discussion. If the BCM were draining the battery on occasion, it would have to be running a program/test/diagnostic/whatever in a loop while the car was parked. I doubt just the BCM alone would draw enough current to drain the battery... So, whatever it is trying to test would be what's causing the battery drain.

All that being said... What accessory that is controlled by the BCM would draw the most current while running its test?

 

The RAP could stay on but you won’t hear the radio if you’re away from the HHR.

 

There are diagnostics that can get stuck in a loop, as I said earlier. In that case a lobotomy might help temporarily, until the fault is fixed. The testing outlined above would also help the interested mechanic.

 

OK but what do you look for or where to start ?
I can put a battery trickle charger on it for maybe 5 minutes (max) set at 10 amps and the engine starts fine and will continue to restart after this until the problem happens sometime in the future.
And the charging system is normal.
And so is the battery when you load test it fully charged.

 

Thanks George, but why ?