Headlight problem

[dave123]

Hello. My 1977 CJ5 headlights only work on low beam. When I hit high beam, they go out. The dimmer switch has
been replaced. I tested one of the headlights on another car and the high beam was good.

I checked the 3 prongs and got the following: headlights off: all negative.
low beam on: middle prong positive, other two negative.
high beam on: all negative.

Does anyone know which of the two remaining prongs should be hot on high beams?

Any idea how to fix this?

thanx

 

[LauraBoston]

you check for an open or short with the brights on? if you can find a wiring diagram for your brights you can trace the wire..that's where I would start. i know we aint got no books that date back that old at work..good luck..

 

[LBR]

I would disconnect the plug from the new dimmer switch and, with good light, check the spade terminals in that plug. Chances are that, after 30 years of moisture, there is so much rust/corrosion on the hi beam terminal that it is not making contact on the dimmer switch terminal at all. If you or a friend has a sandblaster, poke the plug thru the bottom of a larger garbage sack then tape up the hole, insert the blasting gun in the sack opening and tie the opening off around the gun's hose and sandblast the 3 plug connectors by "feel." Good as new and careful unpacking of the gun and plug equals no sand inside the Jeep. Works for me. LBR

 

[dave123]

Will try that. much thanks

 

[Turbogus]

When I rewired the headlight circuit in my rig with relays and 12 gauge wire I used new pigtail ends for the headlight prongs (running 160/190 thru Hella shells) After a couple of years took a rock through one of the shells and in replacing noticed the prongs on the headlight pushed out one of the wires in the pigtail~something to check for