I just replaced the headlight switch and connector pigtail in my 89 Jeep Cherokee. I've replaced the switch a couple of times, always due to the same symptoms: if I drive a lot at night (which I tend to do at this time of year), I like to dim the dash light right down which appears to result in the headlight switch overheating, filling the truck with the smell of burnt plastic, at which point my headlights become intermittent. When I undim the dash lights the problem goes away. The variable resistor 'spring' on the light dead light switches are always severely scorched with the ceramic insulator cracked with pieces missing. Seems like all the dash lights put too much of a load through the variable resistor in the headlight switch.

Anyone else experience this? How could Jeep have screwed that design up so bad?

 

What brand headlight switch?

 

The replacement I just put in was a BWD or something like that??? (also from Lordco). All the previous switches have been from the Jeep dealer so I assume they were OEM (whatever that was).

 

Are you sure that the wires are attached to the correct prongs on the headlight switch? It sounds like when you activate the dash dimmer you create a short to ground.

 

If I were you I would add a headlight harness upgrade also, seems to help a lot of people.

 

Yup.

 

Ya, pretty sure things are wired correctly. Everything is working as designed (over heating problems aside) and the first couple of headlight switches I replaced utilized the original connector and wiring. That ceramic insulator is there for a reason - that variable resistor can get quite hot when all those lamps are dim - I guess with the extra heat from that dimmer and the heat that's already in the switch from all the lights going through it, there's enough to push the switch over the edge.

In any case, I'm planning on doing the headlight relay mod - as some of the other guys have suggested - just trying to assess a quality kit without overspending.

 

See highlight, I'm not convinced the switch is the problem. What is melting the headlight switch (rheostat) itself or the connector?

 

The wiring is too small for the headlights from the factory. We often replace the harness to get around this problem.

 

Keep in mind the first switch lasted about 10 years before it started acting goofy. I recall when I went to the dealer looking for a new switch, he had a case of them sitting on the parts counter as they were replaced so frequently, the parts guy didn't like to go searching for them. The second switch - not sure how long it lasted but my guess is 8~10 years. As far as what's taking the beating: both the connector and the switch. In the switch case, the ceramic insulator has been broken with pieces missing in all cases. In addition, the connector has been melted and deformed, most recently to a state were it could not be reconnected to a new switch and I had to splice in new connector.

 

To clarify:

We ADD a supplemental harness to take the load off the headlight switch. Super easy.

http://www.ebay.com/itm/CERAMIC-H4-H...-/330997592807


Cruiser’s Headlight Upgrade Harness Instructions


It's easy to install a supplemental headlight harness.

From the factory, the voltage to the headlight bulbs travels from the battery, inside the cabin, to the headlamp switch, and then back out to the lamps via undersized wire. It's not uncommon to find only 10.5 volts at the lamps.

The supplemental harness is installed so that it provides battery voltage to the lamps and is just triggered by the factory wiring. The result is about 30% brighter headlamps and headlight switches that don't melt and burn out.



Absolutely plug and play. Remove grille and headlamp bulbs. I fed my harnesses from the passenger side starting between the battery and the back of the headlamp housing, over to the driver side. Plug the driver side bulb into the new harness. Attach the new harness's ground wire under one of the small bolts on the radiator support after scraping the paint off under it. Attach the harness to the existing harness behind the grille working toward the passenger side. . Plug the new harness plug into passenger headlamp. Plug original headlamp plug into receptacle on new harness. Attach the ground for the passenger side just like you did the driver side under a radiator support bolt. Attach relays with provided bracket on the passenger side inner fender. Connect power wires to battery.

Revised 12/10/2012

 

In that case I'll say there is no issue with the dash illumination dimmer circuit, the switch is simply worn out after 10 years of use. The headlight switch connector will probably last forever with the installation of an aftermarket H4 harness.

 

Pardon my ignorance (new here)- Is that your product, Cruiser? Also, will that effect the use of my factory fog lights?

 

I don't believe that is his. I recently installed that kit myself. It makes a world of difference. It won't effect your fog lights. They have a problem with daytime running lights sometimes.

 

Thanks for that link - I'm going to order one of those!

On an related note: my headlights have a 'sentinel' feature - I think that's what it's called - if I turn off the ignition before turning off the lights, the lights will remain lit for a couple of minutes then go off. Since the relay kit is downstream of the switch, the sentinel feature should still work (not that I really care frankly).