This is a question for a ZJ electrical system expert. I would guess that the question is pretty deep.


I have a '98 ZJ 108K miles in great mechanical condition. But the cluster lights have all at once quit. Fuses and bulbs are fine. I suspect an issue with the BCM. I sent the BCM to two "module repair shops" (SCAM ALERT). First sent it to Module Experts in Jacksonville for a $149 repair. They tried to scam me for another $500 for a "remanufactured" module promising that my original will be remanufactured. (Repair, remanufactured seems like the same thing) I refused. Sent it then to G7 Computers in New York for a $275 repair. Suspecting this company might be a scam, I put a tamper seal on the PC board inside the module buttoned it up and sent it on. They returned the module within 3 days claiming that " there was a hardware failure and much time was spent testing, diagnosing and repairing the module". When I got it back, I discovered that they hadn't even opened the module enclosure! The tamper seal was still intact and the conformal moisture proofing (rubber coating) was undisturbed. There was no evidence of solder work. Another scammer. Of course the module is still not functioning properly. Now what?

I measured signal level at the headlight switch module connector. The cluster dimmer signal (WT/BK) on Circuit 707 shows a voltage swing from 2.5 to 3.7V depending upon dimmer position. This is measured in relation to chassis ground. The cluster light driver (Orange) on Circuit E2 is showing high impedance - no signal, as would be expected if there is no lights. This was also measured in relation to chassis ground. I did not disconnect the lamp circuit when I measured Circuit E2 so the measurement would be under load.

I could swap out the BCM for a working junkyard module, but am concerned with the stories about incompatibilities with the security system. Connecting a VTTS enabled BCM could cause VTTS to turn on in the PCM resulting in headaches with alarm and immobilizer. But I'm not sure. I would think that my '98 has VTTS in the original BCM and therefore the VTTS is already enabled in the PCM. I don't want to put in a different BCM in, only to have issues with VTTS. Yes, I know that there are some work arounds like shorting Circuit G71 and pulling the dome light fuse. But I'd rather keep things clean. Also, I am aware that the vehicle odometer value is stored in the BCM. So if I put in a different one, my vehicle will display that module's odometer. I also have understood that most STEALERS don't do module programming on these old girls. It takes the legacy DRB3 computer to program the ZJ which many Chrysler Jeep garages apparently no longer have. I doubt that my regular independent mechanic, who is a brilliant mechanic on powertrain, brakes, cooling and suspension, has such a tool. I'm the original owner of this car which I really enjoy driving. But there is a limit as to how much cash I want to invest into just making it work.

So my question. What is the best way to get my cluster lighting back (short of using a flashlight! )?


Sorry for my long question. TIA for any experts.


PS. Tried to get an answer from a "a Certified Jeep Mechanic on Just Ask". Cost me $35. He told me to take it to a dealer!

 

Remove the headlight switch. Take the outer cover and the white cover inside off, revealing the circuit board. Resolder all the joints and reassemble. That should fix it.

(Edit) Mine is the same year and had exactly the same problem. It's apparently a common problem having to do with the solder being poor quality. The fix is really easy and worked perfectly on mine.

 

Any updates?

 

Yes. First thank you for your prompt response. Sorry for my delay. I was oversubscribed this week and was unable to get back on to respond quickly.

The problem was not the light switch dimmer module. I replaced it with a new one that I picked up on AMZN. The issue did not disappear. My thought was that if the new one worked, I would try to reflow the solder on the old one as you had suggested. But since it didn't work, it went back to AMZN. The new part had a mechanically defective fog light switch that didn't latch the fog lights on.

My next step was to go out to the U-Pull-It salvage yard here in SE Michigan and salvage a couple of BCMs from 98 ZJs. The first one worked and the cluster lamps came back to life. The second BCM did not work. My vehicle has VTSS (security) enabled and the second BCM didn't. As a result, the car died within 2 seconds after a start. Apparently it can be reprogrammed but since I only needed one BCM, that unit will be returned to the salvage yard for a refund since I cannot use it in my vehicle. Funny enough they guarantee their parts for a full refund within 10 days. I also got a couple of flipper window struts which were also garbage.

So my cluster lights are back in operation. But that leads me to the next problem, albeit more cosmetic until the time comes to sell this beloved family SUV. The mileage shown on the ODO is almost 2X the actual mileage on the vehicle. The mileage from the wrecked salvage car is stored in the BCM. I contacted US Speedo in Flint, a cluster repair depot who is authorized by DOT to do rebuilds on odometers and they told me that the mileage cannot be changed. Apparently these BCMs are not very robust. So I might be stuck with a mileage affidavit to list the correct mileage against the ODO when it comes time to sell the car. I also made a stop at the local Jeep Steeler. They have a DRB3 computer with a ZJ interface card. But nobody in the service department knew if anything could be done on my used BCM. Funny thing is that this car was manufactured before many on their crew were born! Their master mechanic, who has been working on Jeeps for over 30 years will be back on Monday, and I've asked for a call. If anybody has any coaching on the problem, please let me know.

The good news is that I can drive at night without a flashlight again. Now I'm going to do some additional work on the vehicle to address the sagging/pulled out headliner, the driver seat cover wear and to remove a small amount of corrosion on the bottom of the deck lid. The latter seems to be an issue on all the junked cars that I looked at when I was trying to salvage a BCM. Mine is mild compared to the rot that some of those cars had.

Thanks again for your reply.