Strange Gauge Light Issue in my 88

No gauge lights in a Renix era XJ.

Firstly, I have done my due diligence, and searched thoroughly for threads on my topic; in fact, I have been reading for the better part of three days on this topic (threads like http://www.naxja.org/forum/showthread.php?t=933795, et. al.) with no matching problem. Several similar, but none matching.

Second, my headlight switch is brand new and I fixed a short in my rear liftgate which was blowing my park lamp fuse (worn wire in the harness where it goes from unibody into liftgate) and know my way around a DVM, but this one had me perplexed.

I was thinking that my gauge lights were not working from a bad variable resistor (spring) in the headlight switch as stated in several of the other threads I have read, but I doubt it is the issue, since it is a new Crown one installed recently and when I replaced it, the harness looked virtually brand new even though its 20 years old with no melted wire/cracked connectors. The strange part of this issue is: the 5A inst light fuse pops when the ignition is in the "run" position, but if you pull the keys out of the jeep altogether, and turn on the headlights, the fuse does not pop, but neither to the gauge lamps. Also, when the 5A fuse does pop, there is no, "gauge light for a moment until it pops," phenomena, leading me to believe that the short must be somewhere up line from the first bulb in the circuit, but in the schematic, they appear to all be in parallel with each other (except for a few) as seen in the screenshot from my FSM below:

Image Deleted by Moderator

So I am at a loss. I guess I need to start tracing wires from the headlight switch the fuse block, and then to each gauge bulb? Anybody else run into this problem before? I hope someone has a suggestion that hits the nail on the head before it comes to tracing...

Anyways, thanks for any help you can provide!

Happy wheelin',

Edit - Thou Shalt Not Post FSMs or Links to FSMs, in Whole or in Part. If it's necessary, you can pass them back and forth using an email system outside of , but we can't allow copyrighted goodies to go through us here. I understand your problem, but please understand ours (and as an author, this is especially sensitive to me...)

If you take a minute and draw something out by hand, note that it's no longer copyrighted - the information isn't protected, merely the presentation of that information...

Tough one. I'd pull the plug off the back of the headlamp switch and check for resistance of each circuit from there. It should have at least the resistance of a light bulb. If it goes to almost no resistance, the short is on that circuit. If this happens when you turn the key to run, and not when key is off, that's another indicator.

Probably lots of other ways to do it, but that's my guess.

Scratch head? The only place I can think of where the ignition switch and the illum circuit come together is at the clock. Or possibly in the gage cluster.
Maybe unplug the clock and see what happens.
I had a short in the harness between the Illum fuse and the instrument cluster in my 88. I got tired of messing with it, cut the old wire and ran a new wire and hooked it directly to the taillight fuse, bypassing the resistor in the headlight switch. Bypassing the resistor was likely unnecessary, but seemed prudent. I also had a fairly new Crown headlight switch in mine.
I'm guessing when my original switch went out I had a partial meltdown someplace in the harness or a rub through on the harness someplace which caused the resistor in the original switch to melt down.

Thanks for the ideas, I will be checking the wires this weekend and I'll post up any findings for anyone else that might be experiencing a similar problem.

Thanks again,

Well, after tracing wires since my last post, I found a short on the parallel leg that runs to the A/C illumination. The major pain in the rear is that the splice shown on the schematic coming from the fuse is above and to the right (passenger side) of the headlight switch and behind the instrument cluster. Made for a fun time soldering a new splice into the wires after my testing was done... Anyway, thanks for the suggestions, and I have to say, I don't wish this problem on anyone! It was a major BEEEEOOOOOTTTTCCCCCCHHHHHH, but at least its fixed right now, though.

Good luck if you are experiencing the same or a similar issue.

Cheers,

unless an aftermarket radio is wired into the illumination wire incorrectly

Nope, found a chafed insulation spot on the A/C illumination wire that was touching metal behind the dash where the harness runs over to the A/C-Heater unit. Your thought intrigues me, though. Can you explain a little more how the radio being wired incorrectly to the illumination wire would cause a dead short in the parallel splice? I had them all separated at the splice when I did my testing. Not being a smarta$$, just curious. Also, I never figured out why the fuse was only blowing when the ignition was in the run position, but after replacing the chafed wire, everything is back to normal.

Thanks,

elaubuch said:

Nope, found a chafed insulation spot on the A/C illumination wire that was touching metal behind the dash where the harness runs over to the A/C-Heater unit. Your thought intrigues me, though. Can you explain a little more how the radio being wired incorrectly to the illumination wire would cause a dead short in the parallel splice? I had them all separated at the splice when I did my testing. Not being a smarta$$, just curious. Also, I never figured out why the fuse was only blowing when the ignition was in the run position, but after replacing the chafed wire, everything is back to normal.

Thanks,

Click to expand...

Some of the standard wire colors (imports/DIN) don't apply in the XJ. I'm guessing he was thinking the radio dim could be wired into the wrong circuit or even the electric antenna could be wired into the wrong circuit on the radio. As long as you have the diagrams your good, but that blue wire can sure screw you up. I've seen the blue as everything from the electric antenna to the ground on various radios, I've also seen dark green (XJ antenna motor) as ground. The orange wire is another that can throw you, often not a lighting circuit in many radios.
The standard American wire color codes often don't match the Japenes import or the DIN variety. The XJ seems to be a *partial* wire color match to imported radio/stereo wiring in many instances.
A poor ground and crossed wires in sub systems can cause all sorts of grief. The FSM an other sources, do a poor job with the sound system wiring.

I think I see what he was saying now. If the wire color for the illumination on the radio or the adapter kit (not used) was not the same as the orange and black wire that is the parallel leg of the illumination circuit, it might be wired wrong. I hard wired my radio in due to the previous owner completely hacking out the factory harness connector using my FSM and the wiring diagram that came with the radio as a guide. Come to think of it, the chafed spot might have been from the hacking at the harness the previous owner did, and it was just tucked back in there by me (not seeing it because it was too deep and going to the A/C below the radio), since I didn't wire up the dimmer wire on the radio to anything (boy is it bright at night...).

Anyway, all is well; everything works not that I replaced the damaged wire from the splice to the bulb on the A/C unit.

Thanks Mud and others!

Cheers,