Driver's side headlight low beam keeps burning out

[DanHS]

This is a bit of a puzzler, I've gone through two headlights in the last three days, I don't know what's going on. First I replied to the thread on Sylvania Silverstars in OT, then Sunday night I had a flash from my Silverstar headlight and it was dead, although the high beam still works. I thought it was some weird coincidental timing, but then today the old headlight I put back in temporarily, went out just a few minutes after being on.

This doesn't make much sense to me, if I'm tracing these wires correctly, the grayish green wire with a black stripe comes from the switch to the driver's side headlight. From the driver's side headlight plug runs a white wire with black stripe going to the passenger headlight. The grounds from both connect somewhere inside the wiring loom along with the grounds from the marker/turn signal lights and all are grounded in one place with one little screw. If it was the stupid one little screw then I'd have no lights, if it was the green wire I'd have no headlights. If it was the ground then it would have to be altered somewhere before the splice so it only affects that one light, and what could affect that one light through the ground wire?

I'm thinking of just spending Saturday tearing out the old headlight wiring and rewiring from the switch to a pair of relays, may as well replace my busted fog lights and offroad lights while I'm at it and connect them to relays as well. This will get expensive. I hate old wiring. Any ideas on what the problem is, so I can at least try to have two headlights for the week? Also my headlight switch stopped working, is there a reset because there's a tab/button thing on it, but I couldn't seem to push or pull it so I just connected the dimmer switch to a toggle switch as a temp fix. The headlight switch is very difficult to access under the dash because there's other wiring and stuff blocking it.

[mdill]

Not real sure why you think it is a wiring problem, either it gets +12 or it does not, if it does not it does not burn out Vibration can kill a light bulb pretty fast, how is the mount? It may just be you got one bad new bulb, and your old one was on it's last legs (If I did not have bad luck I would have no luck at all )

Oh, and check your voltage when running a bad regulator and or diodes in the alt, can also cause premature light bulb failure.

Mike D.

[710 Burner]

Unless you can point to a specific problem, I would call it coincidence and try a third.
Most of the problems I have seen with headlights is the connector on the back of the lamp itself.

[DanHS]

Third headlight went out. Lasted a little longer but still went out. High beam still works fine on all three lights. My alternator had died but if anything I had low voltage and amps, I think I actually went a couple days on just the battery itself (ammeter bypassed and never got around to installing a voltmeter, so I'm not certain when, but it did totally die). The pass side headlight is still unaffected, driver's headlight was dead when I turned them on tonight after putting in a nice new alt. Checked it for looseness or any way it could vibrate, I can wiggle it a little against the adjustment springs, but in no way could it rattle at all, so I can't see how vibration could kill it. I don't understand what could kill it electrically either. I guess I'll just be doing the relay upgrade as soon as I have the extra cash (stupid winter session class preventing me from working).

[shackwrrr]

do you have a volt meter I would check to make sure your not killing other things on your truck

[BURT]

HEADLIGHT SWITCH

the button on the switch is to remove the stem from the switch , these switches when bad can cause many problems ,you should replace it .on the older rigs power for other things come through the switch . low voltage will hurt stuff , clean your headlight connector contacts , wires will come out of connetor via small screwdriver

[FSJ Guy]

do you have a volt meter I would check to make sure your not killing other things on your truck

X2.

The only real thing that I can see killing your bulbs is too high of a voltage. Check the power going to your headlights. AFAIK, they're wired in parallel on the same circuit. If one bulb is getting too much voltage, the OTHER one is also seeing that same voltage.

If you're having troubles with your alternator, that is most likely the cause of things.

[nograin]

Yes. Same circuit for hi and lo beams until the high/low switch on the floor.
Then its parallel wires to the driver's side headlight connector, and from there to the pass side connector.

IIRC, the ground (which is shared) comes out of the headlight connector and goes to a ground terminal screwed in the top of the radiator support. IIRC, the ground wire runs from the driver to the passenger light but may only have one ground to the body.

Yes. I've had the situation where the insulation has come off of the wires and sometimes they ground out and sometimes short to each other. Check carefully where the wires come into the headlight 'bucket'

[DanHS]

All the wiring that I can see looks fine, what confuses me is how one light could go out without the other being affected. The wiring runs to the driver's side light, then there are two wires on the same tab in the plug, the second running to the passenger side headlight. Then the ground comes back to the driver's side, they splice together in the wiring loom somewhere and ground on the body. The only thing that isolates the driver's side light is the section of ground wire before the splice, but there's no way that can short because it's the ground, and the high beam is unaffected. It can't be a problem in the positive lead because the passenger side light would die too. It doesn't seem to be vibration because the headlight bucket is secure. The alternator did begin to die before this, but I don't see low voltage killing a light. The only other electrical thing that died was a marker light, but it was cracked and corroded when I removed it, so that was dead anyway. Nothing else was affected.

All I can think of now is perhaps the Jeep Gods are trying to get me to do a relay switch upgrade, so I guess I need to pick up a couple relays, some different color wires, and a new headlight switch, and start soldering.