Question on Changing the Body Control Module

[Maui_Dave]

I recently bought a 98 Limited (5.9) It came with some electrical issues:

1. Memory for driver side mirror has a mind of it's own. Likes to
reset to a specific setting on occasion.
2. If the car stays off for more than 15 minutes the AC will automatically
be selected at start up. (I think these two problems are related to
Poor Memory Issues).
3. If I turn off the car and then manually turn off the headlights. They
come back on as if it was in auto mode. If I turn off the lights before
I turn off the engine it works just fine.
4. But my personal favorite.... the headlights have an attitude problem
with each other. When one is on high beam, the other is on low beam.
Why can't they just get along! When I toggle the high/low switch on
the column they trade places. It's kinda funny except for the other
drivers getting blinded by one of the lights. The poor high beam
indicator is on all the time because he has no idea what the hell is
going on !

My guess is that all of these functions pass through the BCM Body Control
module. I'm just trying to find out if I should replace it or if I'm throwing my
money away. In the mean time I bought a Factory Manual and I'm going to
spend some quality time with the schematics and my multimeter.

If anybody could shed some light that would be cool.

Thanks - Dave

[fredjacksonsan]

Very funky....I'm not the best one to comment, but the BCM sounds like it makes sense, if all those functions go through it.

Be interested to hear what you find out.

[Maui_Dave]

I used to work on helicopters but this one definitely borders on twilight zone.
I guess this isn't a normal malfuntion with Jeeps, so looks like I'm going to have to whip out the multimeter. I'll give you a heads up when I find the problem. I do love a good challenge

[legalfee]

Don't know about the other problems but my drivers mirror memory does not hold either. I read a post in another forum that this can be cured by removing the mirror, cleaning the contacts and applying dielectric grease. I will try this on mine and let you know if it worked. SJ

[neon_rt]

#3 is a normal function, you will find it in the owners manual
If you turn off the key when the lights are on and then turn off the lights, they will go out for about 1/2 second and then come back on for 60-90 seconds.
The headlight hi/low beam problem could be a relay problem, someone was messing with the relay setup and got it crosswired. The A/C system can be "programmed" if you know the right sequence. It could be the previous owner "programmed" the A/C to automatically come on when the vehicle is started. There are several things that you can program to automatically occur when you start, it's a matter of getting the key sequences right. You may be able to do a Google search and find them. I have played with some of the sequences I've found for my '00 Grand Caravan and they all seemed to work. Since the BCM is essentially the same for Jeep and Dodge (same parent company) I assume there are "programmed" modes available for the Jeep as well.

[Maui_Dave]

legalfee - thanks for the mirror tip, I'm going to try that before I mess with the wiring.

neon - I read the factory service manual and they refer to a Diagnostic Procedures Manual. I was figuring on getting a DRB tool anyway so I'll start looking for the manual as well. I'll also do the google search as well.

Thanks guys...

[viprjr]

hi all, 2001 jgc (wj i think), just bought it and have been warmly welcomed to their world of electrical probs. here's mine: memory seat function inop (i've got heated seats btw), horn doesn't work (from wheel or when hitting panic button on key fob), that's about it for now...any thoughts? bcm? that's what i'm thinking...thanks in advance!!!

[Maui_Dave]

Well I finally found time to try and diagnose some of the problems.

According to the schematics. The headlight system worked flawlessly without the bulbs in but was a problem when the bulbs were in.

Soooo... low and behold the genius before me put a 9007 headlight on one side and 9004 (what it calls for) on the other. Wella - the problem!

Installed a new 9004 headlight bulb and the problem is no more!


As far as the memory on the driver mirror. That still exists. I disconnected the battery for a couple hours and it worked at startup but the problem came back. I bought the Body Diagnostic Manual and it basically says to either replace the door module or the mirror. Depends on what the DRB tool says. Guess I got to get me that one next.

Has anybody had any luck with the $130 DRB's out there or are they just a waste of time?