Fiddleplayer

I have a 1995 Jeep Cherokee that I have owned for many years. It just developed an intermittent headlights problem.(both simultaneously) Everything is okay with low beams on and then if I switch on the high beams after a short while all lights go off including the dash lights. If I pull back on the high beam switch the brights will come on but momentarily. I had a head light problem over a year ago and the dash switch was bad and I replaced it. I am hoping that its not the bright dim switch. Could there be a bad relay somewhere! I almost would doubt an intermittent ground because the lights will stay on if I hold the bright switch all of the way back.
Any suggestions
Thanks
John

wingless

Welcome to the forum.

The 30A Fuse F10 is the main power feed, to the 15A Fuse #12 and to the 25A circuit breaker integrated into the headlamp switch. There is also the 15A Fuse #7 for the high beams.

The circuit breaker powers all the automatic functions.

How is the functionality when the headlamp switch is manually rotated to illuminate the Park lights or also the Headlights?

If manual operation is good, then there may be an issue w/ the Ultralight Sentinel Module.

Fiddleplayer

Thank you for the welcome! There are only manual headlight functions on this jeep. Is there still a circuit breaker and maybe could be going bad??

wingless

This reply shows a failed instrument panel dimming module, a common failure. It may explain the dash lamp problem.

If this were mine, then I would use a volt meter and a schematic to trace out the fault.

Another option is to measure the switch resistance on an unpowered circuit, also per the schematic.

dave1123

Sounds to me like the circuit breaker is doing it's job. Somehow, you're pulling amps near it's rating on high beams so it's getting hot and tripping out until to cools. Does it function normally on low beams? Does it have aftermarket driving lights that are wired to the high beam circuit that may be shorting out?

Fiddleplayer

Okay, I am a little confused here. I was looking at the fuse box drawing on this sight and there is no circuit breaker pertaining to head lights there unless I'm missing something nor is there one in the Hayes manual. My jeep doesn't have head lamp delay which is where some are directing to. It seems like in my diagram it may be straight forward from headlight switch to bright dim switch. I cannot be totally sure of this because my Hayes book only shows 1997 and later in the typical front lighting section for some reason. My book is 1984-2000. Unless the 1997 and later is supposed to be the same as 1995. Sometime this book gets a little vague. And as well as I originally posted, my dash light problem and brights going out happen at the same time. It is not 2 separate problems.
Time to pull out the DVM,

wingless

Here is the applicable page from the '94 ZJ FSM, which should be identical to the '95 ZJ. The circuit breaker is circled.

Use the FSM, get the correct FSM for the vehicle. This document is required for proper maintenance of the vehicle.

dave1123

It looks like the circuit breaker is inside the headlamp switch.

97grand4.0

Correct. There is no fuse to the headlights. I am guessing that the CB in the switch is to prevent overheating if the switch goes bad.

Fiddleplayer

Well as a response to everyone that helped me out on this, the problem was the headlight switch. I had a feeling from the beginning that it was. I replaced this switch for a different problem about a year and a half ago and was surprised that it would go bad that fast. I purchased that one on E bay and the one that I just installed came from a reputable automotive parts place. Plus once I saw the drawing it was made clear to me that the CB was in the switch. The Hayes manual was very unclear of this. So happy ending, problem solved!
Thanks everyone for your input. . .

97grand4.0

Cool. Now if you wanted to go one better and never have it happen again, consider putting in a relay circuit that routes all the headlight current out of the switch, and never overload it again *(or even come close to it). Also, as they heat up the resistance goes up and you actually loose voltage to the headlights over iime - dimmer headlights,

Fiddleplayer

That's not a bad idea when I have spare time and that's not too often! I still have a fuel tank to replace, put in rear shocks that are frozen in place, fuel line replacement, whew! Lots to be done.