How to repair a Body Control Module?

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letsbangout

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I believe I'm having a problem with my BCM; my rationale is below. Two things, 1) Were BCMs in the 99 Yukon ever recalled? I read somewhere that they were.. hoping someone has authorative information on this. 2) If no recall applies to me, how do you refurb one? It's my understanding that they suffer from (among other things) problems with a cold solder joint, just like the wiper control module. It would be nice if I could fix mine by repairing a few simple components. I've got an engineering background so I'd settle for an internal schematic even.

Here's my problem. About 10 months ago I had an issue starting my truck for several days, to the point that I was listening for the fuel pump and was about to buy a fuel pressure gauge. I had a MAP sensor code that'd come up a couple of times beforehand, so I replaced the MAP and it more or less started right up and never exhibited a lick of trouble ever since. That was before I knew about Passlock. And indeed I do recall one instance during that time when the security light was solid or flashing. So I wrote off the problems of 10 months ago to Passlock. But starting a couple of days ago, the Security light would come on sometimes while driving. After a couple of days of that, it finally stopped cranking up from cold. I turned the ignition on and attempted to wait the 10 minutes several times. But during several instances while waiting the 10 minutes, the security light would turn off. I'd try cranking it and no go; as soon as the engine died the Security light would be back on. If I just waited the 10 minutes, the light would intermittently turn off before 10 minutes had elapsed, then it would come back on and I'd be forced to wait another 10 minutes. It took me 4 hours of waiting before I could start my truck! By the time I finally got it started, I had the lower dash panel and the lower steering column cover removed. I clipped the yellow wire going to the passlock cylinder (per GM Bulletin 26) and it's been fine ever since, and it should be fine forever unless I lose battery voltage. Except there's one thing.. now the security light is solid - that's normal behavior. But occasionally it will turn off. There's no reason it should ever turn off unless there were either a problem with the instrument cluster (not likely, it's just an analog light bulb), or there's a problem with the BCM intermittently losing power to some portion internally. This would stand to reason as I've had intermittent problems in the past with other functions controlled by the BCM, like control of the passenger side window from the passenger side button, and functionality of the wiper while simultaneously having a problem with the mist function (and if this were just the wiper control board in the wiper motor, I would think the mist would still work).

Needless to say, I'm highly suspect of my BCM. Any insight would be appreciated. Thanks!
 

SunlitComet

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Up to 2010 there were no bulletins or recall on BCM issues. I can get you hookup diagrams of BCM but no internal schematics are available to the public.

---------- Post added at 02:22 AM ---------- Previous post was at 02:21 AM ----------

if you want just inspect the module for bad joints and repair them.
 

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