Fog light question

I replaced my corroded, abused factory fog lights today. Preliminary testing went well, and the driver's side light functioned properly (on with low beams, off with high beams etc...). THEN, after I mounted them to the vehicle and connected both lights, I got nothing....neither light works, and the green light in the fog light switch doesn't even come on anymore. I'm no stranger to dealing with electrical problems/issues, but I'm just looking for some input from someone who may have a quick fix? It's a 99 and the fuse diagram shows no fuse for the foglights, only a fuse for "day-time running lights". Anyone have any ideas? Thanks if you can help

You've switched supply and ground to the lights??

You may have a blown fuse at this point.

maybe the lights are to powerful for teh stock wiring.

supply and ground are wired exactly the same, I'm even using the factory harness/connector. I purposely wired them exactly as the factories were wired in. They're only 55watt bulbs, so that's factory spec too... Thanks for the replies though!

the fog lights only work with parking lights and lowbeams; I would check the fuses for those.

Sometimes, with metal housings, or the just with the mounting stud, the ground is connected there.

If the supply were connected there instead, when you mounted them to the frame, you would have effectively shorted out the supply.

01-XJ said:

the fog lights only work with parking lights and lowbeams; I would check the fuses for those.

Click to expand...

That's the strange part, everything else(all lights & electronics) is working fine...I just drove it home in the dark about 2 hours ago. I can't really do anything else with it until tomorrow so I guess I'll have to re-check everything again in the daylight. Is there a relay under the hood for the factory fog lights possibly? Maybe thw switch just burnt out or something...I know I've seen posts about the factory fog light switch being pretty junky.

The factory switch does indeed absolutely stink. However someone mentioned grounding out the light when you bolt it up. Sounds pretty likely. Try connecting both lights but don't bolt them in. Let them hang by the wires and see what you get. Also, try hooking up JUST the passenger side and see what happens.

The relays for the fogs are in the PDC as well as the fog light fuses. They are labled, the pdc is the black box on the passenger side next to the battery. Thats provided your XJ came from the FACTORY with fogs, then those relays and fuses are used. If the XJ was wired with the add on factory kit by either the dealer or any previous owners then those relays and fuses are not used and there will be ONE wire running to a single black relay in the engine compartment somewhere. The wire may be bright yellow, mine is... I used a hella fused relay on my 98 when I put the kit in and attached it to the inner fender then used the rest of the hella kit to wire the lights. On my hella kit the ground is attached to the single threaded post that attaches to the underside of the bumper mounting stuff...

Once a year I pull the hella relay apart and use a burnishing tool to clean the high current contacts. When they get dirty they supply voltage but no current. Drove me nuts for a couple of hours till I figured it out, had 13v at the lights but no light.

RichP: Thanks for the extensive info!

I solved the problem today(after blowing 2 fuses!). As it turns out, the fuses in the PDC weren't labeled so I had to check the 00 FSM for the legend. That was how I started to narrow the problem down. Long story short: the wiring harnesses were wired backwards!! (very stupid mistake, but read on if interested...)

Anyone who has factory fog lights can double check this, but in my 99 the male plugs (the ends that are attached to the vehicle) were color coded opposite to the female harnesses! This is all factory keep in mind... so the ground was black on the vehicle end as it should be, and the blue was hot. I had disconnected the harnesses prior to installing the new lights and just connected the black to the black and the blue to the red(fog light hot). The problem of course was that the FACTORY harnesses were reversed! And there was no way of flipping the connectors ar anything because they were keyed. That's what I get for taking anything factory(common sense wise) for granted

As for why the preliminary test worked with the driver's side light... I was just connecting to the factory male plugs where black actually WAS common/ground and blue was the hot wire. I just took for granted that the mating wiring harnesses were using the same color code. Surprise, they weren't, they were reversed.

So maybe this post will save someone in the future from a hedache or two

Thanks again for all of the replies!

GBA88 and others:

I recently installed foglights on my '90, and I can confirm what GBA 88 encountered- the wires are color coded "backwards"- you need to look at the FSM to verify the connections, and you shouldn't have any issues then.....be safe!!!

Bret S Gray (BN 6339)