Chrysler Repair: Instrument cluster and overhead intermittant when van bumps, grand voyager, fuse box

Question
I have a 99 Grand Voyager and the instrument cluster keeps shutting down and then comes back on. This usually happens when hitting bumps. I lose the speedometer,tach,fuel and temp guage. Also the overhead display does not function when this happens. I've been told it is probably the BCM. What do you think and where is it located? Thanks!

Answer
Hi James,
It could be the bcm but I doubt it. The bcm is located behind the fuse box that is under the dash on the driver's side, wrapped as a package. But when I checked the wiring diagrams I find that both those displays get their 12V power from a section of the ignition switch and so I would suspect that the contacts inside are opening up due to the jarring. Also, if your key ring is heavy that too can exacerbate the problem.
You could check out my theory by monitoring the 12V supply on the dark green/red wire of the black 2-wire plug at the switch and the dark blue wire at the 9 pin of the 10-wire gray plug at the switch to see if you lose the voltage when those displays go out. You might try spraying some electrical contact cleaner inside the switch to improve the continuity of the connections.
The bcm is possible but I don't see such a direct relationship as with the power supply possibilities. And each display has its own ground so that is not a likely explanation either.
Please let me know if you find something interesting. You can reach me quickly via the "rate the expert" tab below using the comments section for your message.
Roland