Headlights Out

[M-39]

My headlights quit working the other day. All other lights work as normal. I figured it was the high beam/low beam switch since only the headlights run through that. Replace it and no luck- still out. Is there a fuse or another component I am missing or any other ideas on what the root cause may be?

[fbomb100]

check the ground wire at the head lights ..

[Nitekruizer]

The headlight switch has a built in circuit breaker that will trip if there's a short or overload. Did your lights work okay the time before when you drove your truck? Did they flash on and off intermitently? Are you still using standard sealed beams or have you upgraded to some type of halogen headlight bulbs?

[M-39]

I should probably preface this with the fact the truck turned into a big project and has been sitting over a year . The headlights quite working several days ago when I tried to take it for a drive (have not had them on in months). One headlight had water in it and no longer turned on and the other was almost as bright a candle. I replaced them with a halogen sealed beam. I specifically asked the guy at the parts store if the halogen would cause any problems. He told me the sealed halogen headlights would be fine, but not always true with a replace-the-light-bulb-only mod. The lights, set at low beam, remain on at idle. When the engine has high RPM and is shaking the truck a bit, they flash all the way on and off intermittently. Only the right headlamp has a functional high beam; the left goes out. Based on some advice, I am thinking it may be the main switch for the lights.

[Nitekruizer]

Well, it sounds like the breaker may be cycling on and off. The fact that one light is very dim makes me think that there's a bad ground or possibly a short somewhere. Before you replace your headlight switch I would say have a real good look at your wiring harness to the headlights for frayed insulation, bad splices, etc. Both high beams come on and then the left one goes out? The headlight switch won't cause one light to go out. It would be all or nothing. A wiring or ground problem would cause one light not to work properly. Of course, you could have more than one problem. I'm not sure how many watts the halogen sealed beams are but, if they pull much more amperage than the standard sealed beams they can trip the breaker. H4 conversions, which are quite often very high wattage, would cause the breaker to trip and can also damage the switch. It might be that the contacts in your headlight switch are worn already though and the higher wattage bulbs will burn the switch contacts away even faster. If you have a test light or a multimeter you can check for voltage at the center terminal of your headlight dimmer switch connector (on floor). If you get a good constant voltage there your headlight switch is probably okay and the problem is likely in the wiring between the switch and the headlights. I hope this helps.

[basketcase0302]

Your parts guy was wrong. 9 times out of 10 the wiring in our truck is simply too frail to handle halogen bulbs or any other type than the normal wattage bulbs. He's long since gone, (was a scam artist i believe)-but his description on how to do the upgrade to the wiring on our trucks still holds true:
http://www.fordification.com/forum/view ... =a#p132255

[M-39]

I just finished replacing the headlight switch and cleaning the grounds behind the headlamps. Now I have nothing. Thanks for link on how to properly build your own harnesses. I think I now know what I am going to be doing tomorrow.

[basketcase0302]

M-39 on Fri Nov 02, 2012 7:39 pm
I just finished replacing the headlight switch and cleaning the grounds behind the headlamps. Now I have nothing. Thanks for link on how to properly build your own harnesses. I think I now know what I am going to be doing tomorrow.

Way...back when he first started selling his "kit" I saw it as a scam. I did mine for about half the price using various vendors from evilboy, (one vendor for the high temperature ceramic light sockets-not plastic like he was selling / another for the relays / another for the circuit breakers) and got the wire locally. Be advised that you can also buy this kit from I believe LMC trucks and maybe somewhere else?
http://www.lmctruck.com/

[M-39]

Root Cause: the headlamp wire going into the headlight switch had pulled. The reason only one high-beam worked was because the socket was damaged on the left headlight and the high beam connector was unable to make contact.

[basketcase0302]

M-39 on Mon Nov 05, 2012 2:11 pm
Root Cause: the headlamp wire going into the headlight switch had pulled. The reason only one high-beam worked was because the socket was damaged on the left headlight and the high beam connector was unable to make contact.

Perfect time to do the upgrade. There are several vendors on evilboy that sell the high temperature ceramic sockets.