Question installing factory fog lamps

so i have factory switches, installed. the 3 wire connector is already there behind the dash ready to plug in. i'm 99.999% sure it has to be for fog lights, the connector gets power when the headlights turn on. then there's an unused two wire connector in front right in the middle behind the grill. right where fog lights go, so i assumed it was for fog lights, and just a short harness is missing for not having the option. i figured i can just wire the two lights into it.

BUT, i tested the connector today, and it doesn't get power with the key on, headlights on, and fog light switch on. is there a relay missing somewhere for the lights, or is this connector for something else? what am i missing to plug in factory fog lights?

If your MJ/XJ did not come with factory fog lights, there will be no fog light relay(s). At least I haven't seen any yet. The output from the dash foglight switch ends at the 10-pin connector in the engine bay, left front. I had to pick up the ground applied by the switch there, then add my relays and wire out to my new fog lights. I can send you a wiring diagram via email if you like.

viewtopic.php?f=9&t=12734

page 93 shows the harness. don't know if it will help

My '88 MJ came with the wiring for factory fogs but the kid who had it before me destroyed the actual lights. The relay on mine is on the driver's side, next to the radiator on the back (engine) side of the radiator surround.

thanks guys, any pictures of the factory relay/s would be appreciated. so is that two pin connector for the fog lights, or is that not even there if the truck didn't have the option?

thanks for all the help so far. it looks like i have to add the wiring and relay after the 10 pin connector, anyone clue me in on where that is to save me some hunting. pics?

If you are just trying to get an idea of what it looks like, a few pages (page77) back from the digram above is pics of all the connectors, the fog light one is there too.

I did this exact project to my '87 about 2 months ago. You have to pick up power for the relay from the connector under the LH headlight (fat red wire). That connector also has the feed from the dash switch (black with a green tracer if I remember correctly...check the colors on the switch in the dash). The relay will need a new ground unless you use the complete donor harness but that's easy enough. You'll also need the front part of the harness from the donor truck (the only extra wiring I found in the front was for the dual tone horn). The fog light outputs are directly from the relay so if the relay isn't there the connectors aren't either. The relay is located behind the LH headlight and there's a pre drilled hole ready for one if it isn't factory installed.

The cleanest way to install it is to grab the entire front harness from the donor truck. It will plug in to the connector behind the LH headlight and controls the headlights, turn signals, and fog lights...but in my case I couldn't maneuver the plug out from behind the header panel. I pulled the harness and stripped what I needed and it worked out fine. I couldn't justify pulling the header panel solely for the purpose of being 100% OE correct in wiring. As it is you can troubleshoot the fog lights with the factory manual because it's wired correctly...I just missed 2 pins on the connector.

And remember you have to be using the low beams to active the hot wire to the OEM fog light switch. Fog lights won't work if high beams are activated, well not legally in most states. However I got to admit I jerry-rigged mine so they can work independently of the orig switch.

thanks guys, i don't have a donor harness. i just had the lights laying around for years. then stumbled on factory switches. then when i looked behind the switch blank i saw that connector, tested it and realized it had to be for fog lights. so all i'm missing right now is wiring under the hood basically.

Those that have added foglights to MJs that never had them, are you getting a factory replacement relay or a universal type?

EDIT: I am referring to installations that use some/most of factory wiring.

The factory relay IS a universal type. It's the same relay as any of the relays in the relay bank on the right side inner fender (if you have a Renix model).

on mine i ended up getting my hands on a factory headlight harness all wired for the fog lights.

On the one I just pulled it had the 2 relays, and two seperate connectors for the fogs lights in their respective locations. All of this was in the header panel harness and disconnected at the ten pin connector. If you have the whole harness already, then just wire up the switch and the lights and go. I have no idea what the single 2 pin connector might be in that area. Maybe for a temp sensor on the models that had the info center? Thats usually where they are on new cars. Good luck.

The factory relay IS a universal type. It's the same relay as any of the relays in the relay bank on the right side inner fender (if you have a Renix model).

I took a look under the cover and saw where there were a few of them that all looked alike. At least two looked identical to the wiring diagrams I've seen with the 85, 86, 87 numbering. Is such a relay like this a behind the counter part, or something the auto parts places have on the floor with the rest of DIY electrical supplies?

on mine i ended up getting my hands on a factory headlight harness all wired for the fog lights.

I cooked in the sun at the salvage yard yesterday. I never thought about getting part of a harness. :( I think I'll add wires before going back for a harness. :dunno: Most of the XJs I saw were hit in the front, too.

I assume this is the 10-pin connector I need to work with:

I know the fat red is the #30 relay power source and the green/black striped wire is the #86. If I am adding the wiring necessary to hook up the relay, what is the most proper way to do that? Splice into those two wires and feed them to the relay, or is there a better way? Are there connectors that will snap inline with that 10-pin connector and let me select which wires to piggyback?

What do you recommend for the #85 ground path? Create one to the inner fender? Thanks for the advice.

yep, that is the connector, the green/black tracer wire is the power from the switch, the wiring is in the cab for the switch already also. i don't know of any connector you can use to piggy back, if i had it to do again i would've just installed the complete headlight harness that had the fog lights on it.

you can do what you said basically, splice the power and switch wire from the connector, supply a ground, and the other wire from the relay powers the fog lights. there's a red wire, and the green/black wire that are at that 10 pin connector just for fog lights, they dead end there, so splicing them from that harness is fine.

yep, that is the connector, the green/black tracer wire is the power from the switch, the wiring is in the cab for the switch already also. i don't know of any connector you can use to piggy back, if i had it to do again i would've just installed the complete headlight harness that had the fog lights on it.

 

you can do what you said basically, splice the power and switch wire from the connector, supply a ground, and the other wire from the relay powers the fog lights. there's a red wire, and the green/black wire that are at that 10 pin connector just for fog lights, they dead end there, so splicing them from that harness is fine.

I think you just fixed me up! 1. I didn't think about the green/black tracer being a deadend since it's just for foglights, and 2. I assumed that red wire powered more than than just foglights.

In the photo I linked, are the two orange and black striped wires running to that white "block" on the inner fender a ground path for something? If so, I imagine there is no reason I can't use it for grounding, too?

no, those orange wires going to the white thing is a ballist resistor for your fuel pump, leave that alone.

make sure you get the right red wire, the one i used dead ended right there, and on the fog light equipped harness thats the only thing it was there for, so on the engine side it is a dead end.

i'd say use a self tapping screw and make a ground on the fender, i had all sorts of weird ground issues right after i did mine, and it was all just from a weak body ground.

no, those orange wires going to the white thing is a ballist resistor for your fuel pump, leave that alone.

 

make sure you get the right red wire, the one i used dead ended right there, and on the fog light equipped harness thats the only thing it was there for, so on the engine side it is a dead end.

 

i'd say use a self tapping screw and make a ground on the fender, i had all sorts of weird ground issues right after i did mine, and it was all just from a weak body ground.

Thanks for the fuel pump warning and ground advice!

I only have one red wire at that connector, and it's thick. I moved the connector around, and I can see that it does deadend there. I just need a set of lights, a little bit of wiring, and a relay!