Drfletch

Afternoon everyone. I recently purchased a 97 XJ for my son as his first car and after getting to spend a week with it we have started to find many electrical gremlins.
About the vehicle. 97 4.0 auto. 243K miles. Body is straight, no rust and no signs of other issues such as flooding etc. Had a single DIN aftermarket radio and FM modulator. Everything functions as it should with the exception of the below.

Issues observed in the past week:
1) The voltage reading stays steady at 13-14 most of the time but sporadically while driving and idling will fall to 9-11. Everything appears to continue to operate as it should.
2) In between starts and running the battery will drain fairly quickly. 10 mins in between starts appears to be enough to need the jump pack.
3) When the headlights are off, the vehicle mile readout on the cluster will dim, and the front blinkers and brakes will illuminate when the brake is pressed. This does not happen when the headlights are on.
4) I observed all interior lighting has been removed. center console, under dash lighting, glove box, and dome lights. I suspect this was a previous owners last ditch effort to not have to deal with the real issue that I now own.
5) found the horns unplugged because they are constantly on.

I'm going to start by having the alternator and battery tested this morning and then start assessing the grounds for connections.
I removed the radio and FM modulator to see if they may resolve anything.
Nearly disassembled the dash to check for funky wiring issues and observed nothing out of the ordinary except for a single blue wire in the drive foot well that was factory labeled "BRAKE" with a white sticker attached to it.
As for the horn I will check the relay (still cant find it) and the in wheel switch to see if it has failed on.

Just curious if anyone has had similar issues and provide helpful quidance.

Thanks!

4.3L XJ

The tried and true method of chasing down a battery drain is to start pulling fuses and see if it still persists. I suspect though that the battery is not that strong to drain that quickly. I can just about run a starter for 10 min with my batteries, although they are pretty good batteries.

BlueRidgeMark

This is a most excellent first post! Thank you!

See my sig, #1, for a link to pictures of the ground locations. Very helpful.

Do pay close attention to the quality of your battery cables & connections. Corrosion can do strange things.

Your headlight switch is suspect. They often overheat and start doing strange things. (The circuit is marginal, and an aftermarket headlight harness is a good way to take the load off of it, but you have other fish to fry, first.)

Other than that, it's one circuit at a time. Tedious, but necessary. Do yourself a favor - make a WRITTEN list of what you test and what the results are. You will not be able to keep it straight in your head, and you will get very frustrated and find yourself re-checking things over and over.

Sounds like you have a mess to clean up, thanks to an idiot. It's a crying shame what people will do to avoid thinking!

djgrayxj

Note from DJ

Do you have a home Computer even a Tablet will do? The reason for this question is there a website link that that you can download that has a complete 97 XJ manual; that even has wiring diagrams.

Did your battery pass the load test?

Information on your mystery Blue wire; this was include in the main wiring bundle by the factory from where you found it to the cavity behind the spare tire. Its purpose was to provide you a path for a variable voltage path in case you were towing a trailer with electric brakes. The only thing they provide was the wire.

I’m guessing the reason that the bulbs were removed from the overhead lights is they are notorious for the wiring inside the lights shorting out inside. The original incandescent bulbs provided so much heat if they were left on for a long period of time; they melted the plastic lights which caused a short.

This is all the information I have for you at this time.

Welcome the used Jeep XJ world.

djgrayxj

Note from DJ

Here is an example what you can have a click away; if you have something download to and keep.
You wanted information on the horn relay.