It sounds to me like you may have had a grounding or a contact issue on your BCM. I would not necessarily replace the BCM yet though. To be on the safe side you may want to double check the ground and other contacts. There is a possibility that merely unplugging then replugging it cleaned the contacts for now, but the problem may appear again sometime in the future if the contacts aren't good.

I am really glad you were able to isolate this, and that it wasn't too costly.

Ref

 

It was too late I had already bought the BCM before realizing that unpluggin and plugging it back in would "fix" the problem. Either way I got the new BCM and decided to check all the pin connections and wire connections (before I read yer post lol). I found 1 of the connectors on the white block (has a thicker blue wire looks like 16 gauge wire) looked "different". It was "loose" so I tightened up the metal tab to make it tighter. We shall see if that fixes the issue.

Also I took apart the ignition switch cause well I am curious and wanted to see what it looked like inside lol. The looks like 12 gauge white wire has some charring on it so it got hot at one point in time. Thanks for giving me hints at what to look at besides the BCM. I think it was a combination of the BCM AND the ignition switch. Meaning I think the ignition switch going bad may have sent a short to the BCM causing the BCM to go haywire. Wonder if I could sell the old BCM for some small amount instead of throwing it in the trash.

*edit oh and sorry for the vague wire descriptions.. I didnt look at the wiring schematics in my manual to see what wire does what. Mostly I am still learning how to read prints and what all the descriptions mean. I can see what a relay, diode, capacitor ect ect but there are a few things I still dont know. I mean I have only been an Industrial Electrical Apprentice for just over 1 year lol.

 

When I get a chance ill post pictures but that ignition switch had some major arcing in it. So my guess is the arcing caused the BCM to "flip" out thus causing more issues than it needed. This thing has been arcing for a long time. I have a feeling this is why my door locks wouldnt work right for a while now nor the auto sliding door. There is an oily substance throught this switch so I believe this is the reason for the arcing.

Now on to change my o2 sensor since I believe it is bad but that is for another thread lol.

 

well I guess it didnt fix it. wife said it did it on her whole trip somewhere. I cant procuce it again so now I am at a loss. Seems to always happen for her and never for me.

 

Ok, it is definately sounding like a ground problem or possibly a major electrical line, like a major electrical conductor that carries positive voltage to these specific systems. My Silhoette is a 2000, so my Haynes manual only goes to 2001, but let's see if we can troubleshoot this together. My questions may seem a little odd, but humor me, because like you, I will try to get down to basic root/cause analysis.

To start out with, (I'm certain this will seem odd...) but I am trying to eliminate unnecessary variables so that the van is being driven the same by either you or your wife for this troubleshooting process.

1. Is there a physical height difference between you and your wife, or does she pull the seat forward when she gets behind the wheel? Along with that, are these powered seats?

2. When she gets behind the wheel does she adjust the tilt wheel to an area different than you do?

3. Are the side mirrors electric, & do they get adjusted differently?

Do you see where I am going with these questions?

My wife is short, seat gets pulled way forward, & she drives with the steering wheel tilted all the way down & the mirrors adjusted for a short midget sized smurf.

The steering column carries big voltage & could explain the arcing you found in the switch area. Power seats carry big voltage too although I am leaning more towards the wiring harness stretching in the steering column depending on what position the tilt is in. This would drive me to checking connections to ground under the dash, and maybe even behind the dash.

My best guess would fluctuate between a ground under the dash/behind the instrument cluster/in the steering column OR... see below.

Again, I'm going off my older manual, but I assume GM didn't completely redesign the wheel with the 2002 model so... the next thing to check, coming off the BCM there should be a solid black wire going to ground. My guess is it will be a heavier guage wire & that it should go directly to the block or almost immediately going to a good body ground, if not back to the negative battery post itself.

On my older model this BCM ground seems to be the primary ground for ALL of the features you mentioned, the door lock switches, the remote control door lock receiver, radio fuse, backup lamp & PRNDL transaxle range switch. Other BCM controlled circuits have different grounds.

There is a chance that this solid black ground wire has multiple termination contacts and you may just need to do due diligence & track them down. Again, remember to eliminate the variables caused by different drivers when trying to locate these problems.

I sincerely hope I have been some help.

Ref

 

ok ill answer your questions lol.

1. Yes they are powered seats but we both normally dont move them. We are the same height though I do weight about 30lbs more than she does.

2. She adjusts the tilt all the way down (which I hate because when I get in I jam my knee/leg into the steering wheel) whereas I set the tilt to be just below the "letters" so I know what gear I am in. This is about 3/4 up. Cant imagine that this new ignition switch would have gotten "stretched" already from that movement but its not out of the question. I will have to check and make sure I didnt make the wire ties to tight. I might even completly remove them.

3. Yes they are electric and yes we both move them. She likes them pointing at the ground I like mine pointing at the vehicles behind me (this is a side joke cause ya know im perfect hahahaha. She gets in and says its aiming into the air). She slouches in the seat whereas I sit straight in the seat.

weird that your manual only goes to 2001 because mine does like 1996-2004 or something like that (I will check when I get home). I will take the cover back off the column and make sure I dont have the wires to tight due to the zip ties. I will say that when I installed the new BCM it beeped at me when I tried to reinstall it. So maybe that is where the short is still. I will look into it further though I am tired of looking at this thing lol.

 

yeah my manual says 1997 thru 2005.

anyways I hope this isnt the PCM. that thing is $400 with $100 core charge. Now the ABS light goes off and on and the air bag light goes off and on (along with random gauges going up and down). Just drove it and no matter where I put the steering wheel it went off. I found the ground for the BCM and that is very tight. I dont believe the BCM has anything to do with the ABS and Air bag lighting.

I checked every friggen wire (even the rear parking aid) and cant find a short anywhere. every ground is tight and not broken... no wires are broken. The only thing I did not check is the wires going into the PCM (why would they put this in the air ducting I havent the foggest). I wonder if because of recent rain and high waters around if the PCM might have gotten wet at some point causing it to go bad???

hmmm it doesnt do it until I let it idle for 15-20 minutes or drive down the road for 15 minutes. Then it does it non stop every few seconds. I did find there is some sort of "switch" that is on the gear shifter shaft. Has a green and black wire going to it. This gets quite hot while driving.

 

Sorry but I have been busy...

Is the wire LT Green, or dark green? Also, are you saying this is two seperate wires? One green & one black? Are there any stripes on these wires?

Green/Black wire as a single wire (should be LT Green) goes to your idle air control (IAC) valve and the other end is at the PCM. The PCM does NOT control any of the other functions you mentioned.

Dk Green & Blk w/wht stripe would direct me to your fuel pump or fuel pressure sensor. How long have you had fuel gauge problems? Did they start with this bulk malfunction?

One common thing I am seeing is many of these seem to go to the underhood junction box. Have you investigated this?

You mentioned having checked the black wire at the BCM. Did you trace the other end? Did you check continuity to verify it isn't broken? I am still leaning heavily toward a simple ground problem. Not an electronic device. Double check the underhood jct box & check if the ground is good by continuity. Something you didn't mention until this last post is that this is an expansion/contraction problem caused when your engine heats up. This info matters. This suggests the problem is most likely under the hood and not past the firewall.

I realize I am all over the page with my questions and suggestions, but I'm trying to get the big picture & see if it seems to point in a specific place.

BTW, I am a electric utility substation relay & protection (electrical) design technician. Electrical relaying & protection circuits are what I do for a living. But trouble shooting these things can be difficult without all the info. Little things like, have you had trouble with or recently replaced your stereo? Do any of these problems generate OBDII diagnostic codes (check engine light)? Do your turn signals & emergency flashers work properly?

I really am trying to help, & don't want to seem like I am sending you on a wild goose chase. Thanks for your patience and understanding.

Ref

 

fuel gauge problem is part of the bulk things happening. its a green wire with white stripe and then a black wire. I was under the impression it has to do with not being able to pull the shifter down until the brake is pressed.

I am now under the impression that maybe my alternator is bad just only after the engine gets upto temp. Meaning it puts out 14.05 volts until the engine warms up and then it either does the over volatage thing or the under voltage thing. But that is just a guess as I have not had time to check this with a meter. I didnt realize it didnt happen until the van was upto temp until I posted that lol. It is something I should have noticed but did not until I drove it quite a distance.

as for your questions I dont mind the help at all and sorry for the late reply. Spent the last 3 days with my cub scout pack at camp . I did check the grounds and they all pan out. The check engine light IS on but it was on before the upper manifold gaskets had to be replaced (I was 1k out of warranty on the first set I had replaced on this thing so I was a little upset about that). The light shows a bank 1 sensor 1 fault which right now is looking to be the sensor itself is bad. That was replaced 3 months after I bought the van and is now almost 9 years old. But I am not to worried about it right now as I am more interested in getting this other issue fixed (though I mention this other issue in case it means something lol).

 

ok found a new "symptom". This problem goes completly away when we turn the radio off. Meaning the clock is still on but there is no music playing.

Ok finally got around to putting my meter on the battery/alternator while this was happening. The alternator was running at 13.9 and would drop all the way down to below 11 and quickly back up to 13.9. So I think the alternator might be going bad.

would a scanner like
http://cgi.ebay.com/ebaymotors/SUPER...motiveQ5fTools
possibly tell me in more detail what "might" be happening? I am thinking of getting a scanner anyways since my truck uses the same reader and well I am sure some day I will have an issue with the thing. I think the scanner would make it easier for me instead of having to goto autozone every time.