Just got done posting this on another forum, finally a summarized list of my life!
Hey folks! I bought my WJ about 6 months and I’ve been loving it, the ruggedness of the outside of the vehicle with all of the interior space it has is amazing! I’ve taken it to the trail twice and nothing broke either time, it’s been great!
Since I’ve had it I’ve gotten it in a better state, replaced the battery, heater core, blend doors, spark plugs, filters, etc
And then the electrical gremlin came in!
Here’s the symptoms:
All gauges will start to flicker, by dropping to 0 or low and then jump back up. After a short bit they stay at 0.
All warning indicators come on, and will flicker until they eventually stay on.
A/C blend doors stop working, if A/C clutch was disengaged when the gauges stop working, the A/C clutch will stay off.
Mileage stops being tracked entirely on the EVIC and dash
Power windows stop working
Interior door locks do not work, key fob does and continues to work.
Heated seats stop working, if you don’t engage them before the gauges die
Power mirrors will make a adjustment noise and then settle
The engine and transmission continue to run like a beast, no noticeable performance drops or issues in the drivetrain.
If I check with an OBDII reader, it shows all tach and speed readings correctly.
Two codes pop up on the OBDII, P1686 and P1698, neither of them show up if the gauges do not act up.
This all happens very randomly. In the beginning it seemed to happen the most when it rained, now it’s random. I drove 500 miles last weekend and didn’t see the problem once. On my commute to work yesterday it happened the whole time. The major thing of note is once it happens it will continue until the vehicle is shut off. Removing the negative contact on the battery used to fix it, so did removing the IOD fuse, however those are less likely to work now.
I’ve done the following:
Replaced Battery
Cleaned and reseated all engine compartment grounds
Replaced various fuses and ensured they are of correct amps
Taken the entire dash apart to look for stray / frayed wire
Taken the PCM and ECU out, investigated the contacts and put dielectric grease in them
Remove the driver & passenger door frames and investigated wires that could be crimped when closing.
Disconnected front & rear wiring harnesses at footwells, investigated all contact points and reseated.
Removed wiring harness from steering wheel, center console, and all of the junction blocks to investigate and clean grounds
I also followed the service manual diagnostics for the gauge cluster, measuring each ground and voltage. All pass.
The jeep is a 2000 Jeep Grand Cherokee Limited v8 4.7, no funky electrical modifications or audio enhancements.
I think my next steps are to replace the BCM and the finally, after I give up, the ECU.
Accessory circuits in the ignition switch are something that might be common to all those systems. I had a pontiac that did something similar. Ignition switch was the culprit.
That said, I suspect the body control module. The BCM is the master for the PCI bus on this generation of Chrysler, and it controls everything you’ve mentioned is having issues, either directly, or by commanding other controllers on the PCI bus. I remember you said you had a windshield leak. The BCM is located under the dash on the driver side, and it’s not waterproof.
I don’t suspect the ignition switch, as some of the issues you’re experiencing (door locks for example) are on circuits that are always powered.
Sounds like it’s time to pull the body control module! We can open it up in the electronics lab and look at it to see if there are cracked solder joints or corrosion problems that could be resolved.
Pulled another BCM from a junkyard, it was missing one pin but seems to work just fine. Going to bring it up to the space tonight to do a full OBDII test and see if the problem recurs.
Ok for an update, today I went to the junkyard and pulled a replacement BCM and interior fuse block. I put the BCM in my jeep and it lasted for a good two hours before the problem came back. Honestly the thing that “fixed” it was disconnecting the battery cable.
As I was getting out of the jeep I noticed something interesting:
With the gauges nonworking, I can park, open my door and the interior lights do not come on. I shut off the jeep and once the gauge cycles to “lights off” the interior lights come on and the gauges are in working order again…
Tomorrow I’m going to replace the ignition switch and then the fuse block
Megging checks for shorts in the wires that can’t be found by a normal meter. It puts a voltage in the wires to find a break in the insulation, even it you cant see it.
Check to see what the wiring is rated for, I don’t recall what automotive wiring rated for. It will be on the wiring. I might be able to loan you a megger.
The hipot & megging are close. My understanding is the hipot test will usually go about 10x the rated voltage. A megger will usually do double the voltage.
I have an amprobe brand, I don’t like it as much as another brand that I can’t think of. I prefer the hand crank, since you don’t have to worry about batteries.