No Head/taillights after replacing switch and dimmer

I searched and read through lots of posts and couldn't seem to find anything quite like this.

Bottom Line: No headlights, gaugelights, or taillights even after replacing headight switch and dimmer switch.

Background: 90 Cherokee Laredo. This summer, I lost my radio, a/c, and lots of lights. Prior to that I had trouble with my headlights...they would occasionally not come on unless I fiddled with the switch (had to hit it just right). So got my ignition switch replaced at the dealer. Drove off and later discovered my radio still did not work. Said F-the stealership and committed to never take it back ever. I still had the headlight problem which just got worse.

So researched here and discovered it may be the headlight switch. Changed it, no headlights or taillights, but radio and dome lights all worked again. Changed the dimmer switch and no change. When I pull the "brights" mechanism back, the brights shine, but it doesn't click and stay into brights mode.

Checked all the fuses, none visibly blown (planning on changing anyway). In the meantime, any other thoughts? The main things wrong are headlights, guagelights, and taillights. Brakelights work. No obvious corrosion or burnt wires or anything.

Thanks to this forum, I will never take my Jeep anywhere but my own damn garage. I'm gonna buy a FSM and keep connected with you fellas and take it all into my own hands. Sick of the dealer.

Look under your master cylinder, see if leaking sweating brake fluid has eaten thru the bundle of wires under it and hope I'm wrong..

On the Renix, the headlights are constant power from a fusible link at the starter relay (actually a bundle of fusible links, which is which, is unknown), then through a circuit breaker built in the headlight switch.
It's likely the fusible link or the spade connector for the large red wire to the switch (at the connector) has gotten hot and relaxed and is barely making contact or the circuit breaker is constantly opening from a short. I'd bet on the fusible link or the connector (plug) at the headlight switch (or both).
The fuses for the taillights and the dash lights are after the headlight switch. Unlikely they would all fail at the same time, to include the headlights The headlights aren't fused in the fuse box (to the best of my knowledge) but the headights through the headlight delay relay are fused (25A).
I've seen the taillights and the dash light fuse fail at the same time, the connector at the the headlight switch did a partial meltdown and caused a short.
If I ever do another headlight switch, I'm going to jump the resistor wire to the dash lights and have them always bright (take the dim function out of the system) and cut the resistor coil out and throw it away. They cause way to much trouble.

I just went through the parking lamp nightmare.
The dash lights are fed from the parking lamp circuit, so don't worry about them, when you fix the parking lamps they should work.
There are a few connectors to check in the chassis wiring.
The front parking lamp harness has a conenctor just in front of the driver side fender well.
On my MJ there's a connector for the rear harness on the drivers side under the bed, I imagine in an XJ it's behind some plastic in the cargo area.
I started with unplugging those, and testing for voltage. That way you can eliminate faulty sockets/grounds at the lights, and verify that the wire runs aren't the problem.
My problem ended up being under the dash at the headlamp switch. Wires were nasty and looked burnt. I cut back, put new connectors on, put a DMM to the headlamp switch to verify that it was working properly and things started working.

Okay...thanks for the info.

No obvious leakage from master cylinder.

Replaced some fuses and now have everything except headlights. My parking lamps, taillights, everything works fine...except headlamps.

When I hit the brights, I get brights, but they don't stay on. It's like if you want to flash someone you can pull the springy lever by the steering wheel. But if I click it all the way on brights, nothing.

SInce I have replaced both the headlight switch and the dimmer switch, what are the chances one of these is still fouled up?

When I pull the headlights switch, parking lights and taillights come on, as well as guage lights, etc. That tells me the headlights switch is functional. Is that correct?

How can I test the headlight dimmer switch? Is there something that is now working that would not if the switch wasn't working?

If I can "flash" my brights, does that mean the actual headlamp is working?

the switch has two sets of contacts inside.
one for the parking lamps and one for the headlamps.
It's possible for the parking lamps part to work and the headlamp part to be broken.
I would get a volt meter or 12V circuit tester and verify that there is voltage going into the switch for the headlamp circuit, and that voltage is coming out of the switch.
If it goes in and doesn't come out it's the switch, if it goes in and comes out it something after the switch, like maybe the dimmer module.
If there's no voltage at the switch check the fusible links mentioned above.

I should be able to do this with the switch hanging from it's wire, right? I mean I can pull out the handle and unscrew it from the mount and just do it with it loose, as long as it is plugged in, right?

I am new to some of this but *dang* determined.

Oh and would a simple little circuit tester light work or does it need to be a volt meter?

For all you Jeep newbies out there, learn to work on your own &hit. You'll feel so much more peace...even when you can't figure it out as fast as you'd like.

a simple 12V circuit test lamp will do.
you can check it with the switch still attached, you just need to get at the wires.
make sure it has a constant 12v from the battery, and that it's passing that voltage on.
Work from the switch to the lights, following the circuit and testing for 12V along the way at all of the connectors.
There were two connectors for my rear lights, one in the cab, one under the bed.
there was a connector under the dash on the right side under the switch, a flat one that ran out and powered all the parking lamps and such.
and a connector under the drivers side headlamp bucket up front for the front harness.

Ok...fixed. Stupid me. I went and rexamined the switch and harness again and discovered that an old pice of the old switch was still in the plug. Duh. No wonder it didn't work. And it was on the "H" contact which I assume means headlights. Looks like this is where the switch burnt out before and when pulling off the plug, I left a piece in there.

So I replaced the dimmer, probably unneccesarily, but the education is worth it.

God Bless . How do I donate.

become a member.
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J33PsRock said:

Ok...fixed. Stupid me. I went and rexamined the switch and harness again and discovered that an old pice of the old switch was still in the plug. Duh. No wonder it didn't work. And it was on the "H" contact which I assume means headlights. Looks like this is where the switch burnt out before and when pulling off the plug, I left a piece in there.

So I replaced the dimmer, probably unneccesarily, but the education is worth it.

God Bless . How do I donate.

Click to expand...

I know this is old news... but when you say your found the problem and it was at the 'switch'... what switch are you referring too? Is that the headlight switch that actually turns on the headlights when you pull it out f/the dash?

I'm still trying to track down the problem on my son's 87 Wagoner and I have tried everything I know how too. I replaced the Headlight Switch (pull out f/the dash) about 1 year back and it worked up to about 1 month back and now it's having problems. Thanks.