Lighting Issue

Alas another lighting problem. My parking, dash, and tail lights do not come on. (brake lights, headlights, and flashers fine). Iv'e checked the bulbs and replaced them. There are some mysterious wires coming out of my tail lights that i have disregarded. Four black wires from the driver side and one from the passenger. Could this be some trailer set up? Not sure what to do about those. Ive read somewhere that my problem could be my headlamp switch but my other lights work fine. Also completely unrelated, anyone know what the hell the button and switch at the end of the left steering column switch do? ive fiddled with it but it appears to do nothing! All input appreciated, thanks!

-1991 Jeep Cherokee Briarwood

Probably your PARK fuse lower right of the fuse block. The headlight switch can cause this, the dimmer in the switch shorts and blows the park fuse and sometimes the INST LPS fuse also. When the PARK fuse bows it interrupts the power to the INST LPS fuse.

Maybe one of those loose wires shorted the parking light circuit and blew the PARK fuse.

The headlight switch is a multi switch, one section can fail and the other can be OK.

the push button and slide switch at the end of the left side steering wheel lever (turn signal lever) are cruise control functions on my '89 Wagoneer.

8Mud said:

Probably your PARK fuse lower right of the fuse block. The headlight switch can cause this, the dimmer in the switch shorts and blows the park fuse and sometimes the INST LPS fuse also. When the PARK fuse bows it interrupts the power to the INST LPS fuse.

Maybe one of those loose wires shorted the parking light circuit and blew the PARK fuse.

The headlight switch is a multi switch, one section can fail and the other can be OK.

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Park fuse it was, went to autozone and got a 40a fuse stuck it in and all is well. i was soon greeted by faint smoke and an awful smell (wires melting?). i immediantly took the too big fuse out and let it sit for a bit. tried to put the fuse back in and no lights whatsoever. guess thats what i get for using too big a fuse. any reason why the correct size fuse keeps blowing?

Bamajeepguy said:

Park fuse it was, went to autozone and got a 40a fuse stuck it in and all is well. i was soon greeted by faint smoke and an awful smell (wires melting?). i immediantly took the too big fuse out and let it sit for a bit. tried to put the fuse back in and no lights whatsoever. guess thats what i get for using too big a fuse. any reason why the correct size fuse keeps blowing?

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I read the first sentence of your post and screamed don't put that fuse in there.:skull1:

Likely you have a short in the tail light wiring, the dimmer switch part of your headlight switch, the headlight switch connector (which sometimes melts and allows a short) or a rub through (cut) in the harness between the fuse block and the dash where it runs up the seam (possibly sharp seam) to the dash area. Hopefully you blew the fusible link near the starter relay before you had a significant meltdown in a harness.

I'm not one to tell anyone what to do, but using a bigger fuse to troubleshoot is foolish. The damage you can do far outweighs any possible benefits. If you feel you have to use a bigger fuse to troubleshoot, use one five amps bigger and not the largest one available. The wiring in the Renix is marginal at best, instead of redesigning it from the beginning they used (basically) the same harness setup for decades and just kept adding wires instead of redesigning it from scratch.

Just for info a short means a circuit or wire with no resistance. As long as power is supplied it will get hotter and hotter until is burns through (copper core melts at around 2000 F.), maybe after it bursts into flames. If you take a wire and hold it on the battery plus and the battery minus, making a short, the copper will burn right through the insulation, maybe ignite the insulation and likely burn through your fingers too before it eventually reaches 2000 F. (around 3X the temperature of a soldering iron) and the copper core melts.

Thanks so much 8Mud, ive learned my fuse lesson for sure and will check the wiring harness and wires when i get back to her this afternoon. I really appreciate the info!

Bamajeepguy said:

Thanks so much 8Mud, ive learned my fuse lesson for sure and will check the wiring harness and wires when i get back to her this afternoon. I really appreciate the info!

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My bad, I doubt your 91 (I was thinking Renix for some reason) has a fusible link, more likely to be one of the higher amp fuses in the PDC. The rest of my recommendations stand, the likely places for a short remain the same between the Renix and your 91.

what is a pdc?

Google's 749 results about the PDC: 1991 jeep cherokee pdc+naxja site:www.naxja.org