I've read miles and miles of various information on this forum for my 2000 WJ electrical issues, tried just about everything there was to try to fix it, but still no solution. However, today I came across something interesting I thought I'd share with you guys, and maybe together we can solve this once and for all! So if you're fed up with "the gremlin", and ready to either get rid of your ride or hang yourself, don't do it just yet
Intermittently, my AirBag light comes on, accompanied with the lovely chime and the Check Engine light as I drive down the road. Then it goes away for a bit, then it comes on again, then off again... Sometimes, when I start the car in the morning, the instrument cluster gauges are dead and all the warning lights are ON, and power windows don't work. Then, of course, after driving it for a while, it goes away by itself. On the dash I get error codes P1687, P1686, P1685.
What I've tried so far:
- replaced BCM
- replaced battery, cleaned terminals
- checked wiring for obvious cuts/burns/etc - all looks nice and clean
- checked and cleaned just about every connector I could find
- sacrificed a goat to the WJ god
Now, the interesting part:
As I was going through the connectors, underneath the steering column I found, what turned out to be a PCI bus diagnostics port, which looks like this:
This is the place where all the PCI bus wires come in together. The plastic cap that connects to it, is actually a "terminator", that connects all the wires to each other. If you unplug that and start your car, you'll see all the symptoms you've probably been seeing, and more.
So, what I'm thinking is one of them is causing all the problems. It sends a bad signal, a noise, an incorrect voltage to the system, and the rest of the modules pick it up and replicate (since they are all interconnected), thus displaying weird symptoms (in my case, instrument cluster going wild and windows not working), which may not actually be the problem in the first place.
If you're having same issues, let's try this together, see if there's a logic to my conclusion: what I've done is disconnected the AirBag bus wire from this port (since it's my first suspect on the list) to isolate the problem. So far, only the AirBag light is on, I haven't seen any other issues (knock on the wood). I'm going to drive it like that for a few days and see what happens. If nothing else comes on, then I'll know it's the AirBag module that throws out noise on the bus, causing other modules to act crazy.
BTW, here's wiring color-coding:
all wires are YELLOW + PURPLE +
RED - instrument cluster
WHITE - BCM
BROWN - SKIM/ABS
GREY - PCM/TCM
ORANGE - AIRBAG
BLUE - (I've no idea)
Does this sound logical to you? Anyone with 2 cents, please reply! If we solve this, we no longer have to shoot in the dark, replacing various modules hoping to find that one bad apple.