1990 - Intermittent tail lights, sometimes never shut off.

Well, after doing research and deciding the headlight switch failed interally, I pulled it out and ordered a new one and installed it. As my earlier thread reported, the one real symptom of my jeep's illness is taillights. They vanished one night a week or two ago, but strangely reappeared christmas night.

(The running lights, when the headlights are on)

Nothing I do works. When the plug (brown plastic head) is undone they are still on. I pull fuses and they're on. I can't drive it anywhere because it's not awesome for the battery to leave the tails on 24/7. I suppose I could unhook the battery when I park, but it's been very cold in michigan lately and that's a pretty ghetto solution. I'm going to relent to a professional group of mechanics, although I hate to and cannot afford it.

This seems like a deep-seeded electrical gremlin, the likes of which I will not find on my own. This XJ has dual 6" KC daylighters on the aftermarket bumper, I was thinking there's a chance it was rewired and not done great, but I've owned it a year with no problems like this until now.

Anything you'd like to share before I take it in would be great. I removed the lower trim panel up front and tried to prep the area for them to look at.

try checking the ground to the body on the driver side rear behind the plastic in the cargo area.

Have you tried to replace the sockets yet? They are cheap and could be your problem. All you have to do is cut and splice them in.

Haven't replaced any sockets yet.

Do you mean the bulb sockets?

Will check that ground like you suggested, thank you Jess -S

My '98 (also Michigan) developed the same problem, just now when we returned home after a drive of about 2 hours. All of the rear lamps remained on. Messing with - and ultimately pulling the break lamp switch made little difference.

I've disconnected the battery and left it outside the garage, lest the lighting problem is associated with the burning smell that I detected in the area of the rear seat, although I suspect that's maybe my cat converter finally failing, as it's been rattling for a few weeks. BTW the rear passenger floor was not hot.

I just thought I would post this to see if any advice pops up while I am out investigating. TIA. I'll start with the ground behind the spare tire.

sorry - that's "BRAKE" switch. Also, my problem is not with intermittant operation - they're just staying on.

The exterior lights are all switched power (not switched ground), so you have voltage leaking into the circuit somewhere. I'd guess that there's something like a relay that's burned out or a short in your fuse box, but I don't know about the renix era wiring.

The main front-to-back harness runs down the driver's side, under the doorsill trim. It's just a few screws to pull out - start by checking there for physical wiring faults. If that's all good (somewhat unlikely - that's the section that takes the most abuse,) then check behind the driver's side cargo area trim panel.

The crossover harness is, I believe, along the roofline just inside the hatch.

UPDATE: Thanks for the replies. I re-installed the brake light switch, re-connected the battery cable (after letting it sit for approx. 2 hours), and the problem corrected itself - so I am guessing that the suggestion that a relay was defective is probably correct. Thanks, again.

I actually bought a new relay myself yesterday thinking that could be it, so maybe I'm on the right track.

I don't have a book for this jeep, can anyone tell me which of the four relays is the one I need to pull? I believe they run vertically and there's four, they all say made in canada on the outside, unlike the new one I bought.

After I install the new one, I will try the wires before giving up.

I'm sorry, but mine is a 1998 model.

No big deal. I'm trying relays anyways. No dice so far, I peeled back the trim in the tailgate of my '90 and checked those relays, I'm going to look at some in the engine bay, and then give up.

Mine does this now and then. It's always the pedal switch loose in its mount. I just slide it back in against the pedal and the lights go out.