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gregp553

Fog Light Help

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Fog lights with single wire connections came on my car. I added a green correct switch in the console. The green light comes on the switch only when the headlights are on low beams. A new generic relay installed. Power comes to both fog lights (volt meter reads 12.12) when correct switches are enabled. Fog lights do not come on. Are the halogen bulbs the issue? They both look new. Do I need a better relay for halogens? There's no connection on the halogen bulbs for a ground. Is it a ground issue? New bulbs needed? Please help, my limited electrical skills can't handle this one.

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They're H1 bulbs, right? If they'r not simply burnt out, then check that they're grounded through the bulb base/housing to the chassis.  My guess is your light housings have plastic mountings or are somehow mounted such that they're isolated from the body sheet metal and thus you have no path to ground.  Doesn't sound like the relay is your issue.  When you push your green switch, the relay clicks and you get your 12.2V reading at the wire coming from the relay/going to the bulbs, correct? Means the only things left in the circuit are the filaments and ground path. . . 

Also, if your interested, I have a very detailed article on 2002 lights wiring here:

 

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1 hour ago, AustrianVespaGuy said:

They're H1 bulbs, right? If they'r not simply burnt out, then check that they're grounded through the bulb base/housing to the chassis.  My guess is your light housings have plastic mountings or are somehow mounted such that they're isolated from the body sheet metal and thus you have no path to ground.  Doesn't sound like the relay is your issue.  When you push your green switch, the relay clicks and you get your 12.2V reading at the wire coming from the relay/going to the bulbs, correct? Means the only things left in the circuit are the filaments and ground path. . . 

Also, if your interested, I have a very detailed article on 2002 lights wiring here:

 

Thanks! I read many articles, I think this one, too. The bulbs look brand new and there's no extra tab to ground them. The green button allows 12v to the housings. I suspect I need to figure out a way to ground the lights themselves. The lights are mounted to the bumper. Thanks for the input.

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If you have a 74 or later car with the BIG bumpers they are insulated from ground by the bumper shocks.  try running a ground wire from the chassis to the bolt mounting the fog light to the bumper.  Try a test light between the Battery + and the bumper to check for a good ground. 

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2 minutes ago, Preyupy said:

If you have a 74 or later car with the BIG bumpers they are insulated from ground by the bumper shocks.  try running a ground wire from the chassis to the bolt mounting the fog light to the bumper.  Try a test light between the Battery + and the bumper to check for a good ground. 

It's a 72 but the bumper mount might still be the issue. Is the little round cutout on the base of the bulb a place I can attach a ground?

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Just now, gregp553 said:

It's a 72 but the bumper mount might still be the issue. Is the little round cutout on the base of the bulb a place I can attach a ground?

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I should say, in the rectangular cutout. The round one is where the lead wire is.

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1 minute ago, gregp553 said:

I should say, in the rectangular cutout. The round one is where the lead wire is.

The entire light body is grounded, including the mounting bolt.  If you add a wire where the light mounts to the bumper and run it to a chassis ground it should work.  I had to do the same on my '72 to get a good ground.  If you add a ground to the bulb, changing it out later might be a pain.

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32 minutes ago, AustrianVespaGuy said:

If you have an alligator clip, you can quickly test it by clipping one end to the metal body at the base of the bulb and the other end to the engine block or chassis.

It must be these bulbs, even though they look perfect. Here is a tester, grounded to the light housing and stuck into the bulb connection. And it lights up. It's gotta be the bulbs. I hate electrical because I don't know what I'm doing. When I grounded the light housing, the lights still do not come on. Am I crazy, an idiot or . . .

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Run a wire from the spring clip that is holding the bulb into the lens to the body of the light and you will complete the ground to the bulb.

 

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1 hour ago, Preyupy said:

Run a wire from the spring clip that is holding the bulb into the lens to the body of the light and you will complete the ground to the bulb.

 

That didn't do it. Bought 2 incandescent bulbs, took out the Halogens that look perfect, and the incandescents work! They work!! This is why I hate electrical. I don't know what makes something not work, and I don't know why they do work. Is my generic relay only good for incandescent? Are the perfect-looking halogens bad? I don't know, but I'm calling this a win.

Thanks for all the tips.

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Hi Greg--

I'm glad you found the problem and your lamps are working!  But a little clarification: a halogen bulb IS an incandescent bulb.  The key differences to halogen and regular incandescent are adding some halogen gas to the bulb interior and using a high-temperature glass, like quartz (or Vycor or aluminosilicate), to allow the glass to get close enough to the filament so the halogen cycle works without softening the envelope.  And as you probably know, touching a quartz bulb can make it fail from the oils on your skin (it can devitrify, weakening and diffusing the bulb; it could explode from the 30 or more PSI inside).

Now that you know more about halogen bulbs, I STRONGLY suggest you replace your amber-colored "fog" lamps.  Amber is a proper color for signalling or marking lamps such as turn signal, parking or daytime running lamps.  True foglamps are either white or selective yellow (like older French or Japanese headlamps).  See [Daniel Stern on foglamps and lamp colors].  I will note that the Cibie lamps sold by Daniel Stern are good, but I'm not a fan of the H2 bulbs (well, the H2 bulb holders that corrode excessively from the very hot bulb contacts) Cibie has in many of their smaller lamps.

 

Larry

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Thanks Larry. I still don't know what I'm doing with electrical, but I did wire this thing from the installed lights to a relay, then into the car to a period correct green switch. The seller of this car put these on because he liked the look of the fogs, matching the color of the turn indicators. I agree, the color match is nice, and I hear what you're saying. The fogs will be used almost never, but I will consider your advice. Care to guess why changing to these incandescents suddenly solved the problem. Do you think the others were duds, despite looking pristine? Thanks again.

Greg

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3 hours ago, gregp553 said:

Is my generic relay only good for incandescent? Are the perfect-looking halogens bad?

No, relays don't care what the load is, and it seems that you wired it correctly, so well done! But the relay certainly isn't your problem.

Yes, I think those bulbs are just dead.  Sometimes the filament can still look OK even though it's burnt through somewhere.

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