'90 XJ 4.0 Automatic.
The strangest thing just happened to me and I am wondering if anyone else has seen this or can offer some insights on what might be happening.
The XJ is working great but while stopped waiting for food pickup, I decided to turn on the headlights and suddenly my temp gauge pegged. Turned the lights off and the gauge dropped back to normal. Tried this a couple of times with the same result.
After picking up dinner (vehicle running all the time), I started to drive home and decided to try it again. This time the headlights came on and while the gauge slowly moved up a couple of degrees, it didn't peg. Left the lights on for the rest of the drive home and saw no other issues.
One thing that may be related is that the temp gauge has always pegged when the starter is running but as soon as the engine starts, it drops to normal.
I recently went through this Jeep from front to back checking every connection, updating all the grounds and fixing a couple of nit items like slow power windows. I had upgraded the power/neg cables a couple of years ago (custom made kit by Neal) and also added the headlight mod that powers the headlights directly from the battery through a set of relays that are triggered by the headlight switch. Starter and alternator have less than 500 miles on them.
Looking at the schematics, I don't see anything that even remotely connects the temp gauge to the headlights so the only thing I can think to check is the connections on the back of the gauge cluster. I had the cluster out a couple of months ago and they looked fresh but I am out of ideas.
Anyone seen this before?
The strangest thing just happened to me and I am wondering if anyone else has seen this or can offer some insights on what might be happening.
The XJ is working great but while stopped waiting for food pickup, I decided to turn on the headlights and suddenly my temp gauge pegged. Turned the lights off and the gauge dropped back to normal. Tried this a couple of times with the same result.
After picking up dinner (vehicle running all the time), I started to drive home and decided to try it again. This time the headlights came on and while the gauge slowly moved up a couple of degrees, it didn't peg. Left the lights on for the rest of the drive home and saw no other issues.
One thing that may be related is that the temp gauge has always pegged when the starter is running but as soon as the engine starts, it drops to normal.
I recently went through this Jeep from front to back checking every connection, updating all the grounds and fixing a couple of nit items like slow power windows. I had upgraded the power/neg cables a couple of years ago (custom made kit by Neal) and also added the headlight mod that powers the headlights directly from the battery through a set of relays that are triggered by the headlight switch. Starter and alternator have less than 500 miles on them.
Looking at the schematics, I don't see anything that even remotely connects the temp gauge to the headlights so the only thing I can think to check is the connections on the back of the gauge cluster. I had the cluster out a couple of months ago and they looked fresh but I am out of ideas.
Anyone seen this before?
Last edited: