1995 Park Avenue Ultra - BCM Woes

[ian1035nr]

Howdy, everyone

My Park Avenue has started having a series of electrical problems, they're here one day, gone the next. Here's what been going on (and off) so far:

-The interior lights will come on, turn off and flicker
- The driver's side seat can't be adjusted
- Both mirrors can't be adjusted
- Only cold air comes out of the vents
- The warning chime will emit a constant beep after the engine is shut down (this stops if the ignition is turned on, and then back off)
- The car won't respond to its key fobs. Lock, unlock and trunk are all out of commission
- The wipers will do 2 cycles when the control knob is twisted to the "MIST" setting, it used to only do one cycle

Here's what I've done so far:

1. Checked all the fuses
2. Pulled back the carpet to check for moisture
3. Checked the grounds from the battery to the chassis
4. Tried both the car's key fobs, and tried replacement batteries in both fobs

All this started happening within the last 2 weeks, and all these features worked flawlessly before, which leads me to believe the BCM is at the root of it all.

There's plenty of posts on here that tell of the BCM being located under the passenger side of the dashboard. However, there's a lot of stuff crammed up in there.

So my questions are as follows:

1. Where exactly is the BCM in that sea of wires and modules?
2. What does it look like?
3. What's the best way to get it out?
4. Where can I find a new or rebuilt unit?

 

[tb.dxb]

I just exchanged the BCM in my "96 PA. Not because of any issue described by you but because the old one was sucking the battery empty. (Don't know what caused that since it was working fine, the replacement one is the exact same model, doesn't do anything different but is not pulling constant current.)

A new (as in from factory, never used) BCM would be only with dealers, if at all. Personally, I wouldn't trust an electronic module that has been lying around somewhere for 15 years without being used. Anyhow, used ones can be found in salvage yards, or - in my case - on eBay for about 30 bucks.

When you drop the passenger side kick panel, you will find it on the right, just next to the passenger side fuse/relay panel. It is the size of about two cigarette packs and has a single big blue connector. (I also saw a pretty good description on JustAnswer, don't have the link, just google it.) Next to it is another, smaller module which is the one for the door remotes.

However, I am not sure that all of your described issues would be fixed by removing or replacing the BCM. Afaik it is only responsible for theft deterrent and lighting, e.g. locking doors when switching to "D", dimming the lights 25 seconds after shutting off engine and so on. I am pretty sure that seat and mirror adjustment is controlled by a separate module under the driver seat, and wipers are controlled only through the relais under the driver kick panel.
Hence I would assume that you might have several issues, maybe all caused by a single incident. How is the battery and the generator? Both checked and working properly? For me, a bad generator followed by an early-dead battery were the cause for many issues.

Hope this helps. Good luck.

 

[ian1035nr]

Thanks so much for the reply

I went digging around, but the only module I found matching your description has 2 blue electrical connectors on one end, rather than the one. Now, to my knowledge, the '96 Park Avenues had the modules and wiring changed around, which might account for the discrepancy. You have modules my car doesn't, like the MALL module. None of the other BCM-related posts mention a module with 2 blue connectors; they all call for a module with 1 blue connector at one end, and a white one at the other end. However, none of these posts are for a '95 Ultra, or even a '94. There were some architectural changes to the electronics after '93. I'll call my dealer later and see if they can tell me what this module is based on the model number. I already tried them for a replacement unit, and they haven't got anything like that. What they did have, however, was contact information for a company about an hour away from me that specializes in rebuilding modules.

There were a few other posts from people with issues similar to mine (although no one had them all happen at once) that were related to the BCM, including the seats and mirrors (they're powered by the same circuit that activates the courtesy lamps). That's why I'm thinking mine is gone. And it's gettin' mighty cold around here, which isn't too good for those old solder joints. I'll admit that I think the wiper issue is probably just related to the control circuit on the wiper motor, I'll pull that off and check the solder on the relays when I have time.

As for the battery and alternator, I had the same notion it might be a problem. I have a brand-new alternator coming regardless (I didn't know what to put on my Christmas wish list, so I put down some parts I figured would need changing after 22 years). The battery is new, which doesn't mean anything; I think most of us have been burned by a faulty, brand new battery. So I'll take it in and have it put to the test.

 

[94buick123]

I love my Park but if she's not cooperating with helping me solve her electrical gremlins. I am going to try a few more ideas then I will drive her with the misfire until she croaks on the side of the road. A signed title and bill of sale will be in the car and dated on the day she croaks so that when the uber picks me up I won't have to see her again and the junkyard will pick her up and pick her bones clean. I don't have time for this crap. Electrical problems total many beautiful cars and I am not going to throw more time and money at her, one wife is enough.

 

[ian1035nr]

For now I've just ripped out the BCM. I've lost my courtesy lights, retained accessory power and keyless entry, but it'll keep these weird issues at bay until I have the means to rebuild the old BCM. I don't think my Park Ave is liable to "croak" anytime soon; he's only got 190 000 milometers on the clock. Besides, like most 3800-equipped cars, he'll run forever. Whether or not he'll run well, or have all the accessories working, is another discussion.