Headlights don't work now...WTF?
 

Driving to the station this morning-yet another problem. I saw the headlights flicker on and off, then, poof...no more light. Turned the switch on and off--the parking lights work, and my fog lights work. Headlights pop up, but no light.

I assume both bulbs woudn't burn out at once, so is there a relay or fuse I should check? Any idea what would cause this?

Gotta love winter!

Head light switch. Turn it on and see if there is voltage/current at the fuses. Each element in the headlamps has it's own fuse. A total of four.

Ummm....how do I see if there is voltage at the fuses? I have a multi meter, but only know how to use it to bias my Marshall amps!?

Is replacing the headlight switch an easy fix, or a Porsche nightmare?

Set your meter to 12-24VDC, clamp one side to the chassis (anywhere there is a stud or bracket), pull the fuse and stick the point down into the holes. One side will have battery voltage (about 12.8 VDC).

Do your running lights come on? If so this may be the headlight relay.

Check the pig-tail to the headlight at the point, about 6" back, that the cable flexes when the lights go up and down for failed wiring.

What kinda Marshall? :rockon:

It's a '78 JMP MkII 50 watt. I've owned them all, but this one is a keeper!

My running lights DO work. Where is the headlights relay? Couldn't find it on the fuse panel guide list.

SoCal--Which one is it?? There's a "high beam" relay, but no headlights relay...I must be missing it?

You Beam. I Beam. We All Beam For High Beams!

Ah, they call the headlights "high beams"?

Andy, i dont think there is a relay for the lowbeam on the headlights, only a fuse. Check underneath the fusebox cover and there is a diagram which tells you which fuse number you need to check, it might be one fuse for each side or a single fuse for both sides..i cant remember. I dont think the highbeam relay will have anything to do with it.

Do the highbeams still work?

I stand corrected. The high beam relay on the diagram is for aux high beams. The arm and switch on the steering column does all of the high/low beam swtiching. You will need to take your headlight switch out and drop it down below the dash with the connector on to do an active test. Pin #56 should be hot with the switch on (in head light possition -- last). Power comes in on pin X. (with the key on). If your running lights come on there is power at pin X.

Only one of the two elements is driven at any time. There are four fuses; one for each of the two elements in each of the two head light -- #20, 21, 22 and 23.

Tried my high beams--they work fine! So only my low-beams are not working. All 4 7.5 amp fuses are fine. What else can it be??

Though this may be a stretch, swap the fuses around to make sure that they are indeed fine. Sometimes they look ok, but are on the fritz. This happened to me just today.