so i have a 99 2door 4x4 SL jimmy, the original headlights were getting all crusty from the sun damage, so i bought a new pair and decided to go with the integrated fog light ones. i was thinking it would be cool to add fog lights into the factory location, so in my research i noticed i already have a fog lamp relay and fuse in my relay box in the engine compartment. i also noticed on ebay there are a couple people selling used headlight switches that also have the integrated fog lamp switch, and it appears to me that the plugs are the same. i just went and looked further into my engine compartment, after removing my headlamps and spotted a very suspiscious plug that has a neon green cap on it, and its just sitting there clipped in a nice little hiding spot, attached to the same wire loom that all of the bulbs in the headlight housing are connected to. is this the wire for the fog light that GM would use assuming i paid for a factory fog lamp upgrade? if thats the case, i would think adding the switch would control the relay and send power to the plug thus providing power to the bulb. i cant think of any other reason there would be an extra male plug hanging off of the headlight wire loom and tucked away with caps on them not being used.

 

The problem with the factory setup is that the BCM controls power to the fog relay and the switch in the dash is an intermittent connection type switch. If all of the wiring is there (good possibility), the BCM would need to be programmed using a VIN from a vehicle that had all of the same options as yours along with the fogs.

In order to utilize the stock switch without modifying the BCM programming, you would have to get a latching relay, or make a latching relay circuit using multiple relays (see the12volt.com for more information on this).

IMO, if you want fogs in the factory exterior location, wire them up using your own circuit (relay, fuse, & switch). It is by far easier and less costly than getting it going using factory wiring/etc.

 

yea, probably the best way to go. i have no problem doing that i just thought it would be cool. my dad works at a GM dealership and is friends with most of the people in there. is this programming something that can be done at the dealership or is it a part that would need to be sent out? i can also talk to my dad and see if he knows if anyone there could do me the favor. they do a lot of stuff for all of my cars ive had for next to nothing money wise. unless reprogramming this is a pretty involved job then i would still pay something.

 

i bought a universal wiring kit for fog lights. it has the relay, switch, bla bla. i cannot find a place to run the wires through. there was a power wire running for an audio amplifier that a previous owner had, but i removed it because it was cut and i didnt have a use for it. i forget where they ran the wire through, but i see this rubber boot attached to the firewall to the right of my brake booster that has a small hole in it that looks to be where something was shoved through it (like a coat hanger) this being the first place i tried, i put a coat hanger into it and it doesnt go in very far, and i tried pivoting and wiggling the coat hanger all over the place and cannot get it to go through at all. so i did the inverted cork screw and laid on my back on my driver floor to see up there. i cannot find a grommet of any kind that goes through the firewall. i looked some stuff up on here and someone said to use the passenger side, theres a grommet there. i looked, and i saw a large rubber grommet that had 1 thick wire/cable? going through it, thats it. i did not remove the sound deadening pad since its glued to the floorboards and i dont have any glue to reapply it.

so after all of that i happened to notice that my headlight switch has locations for plugs to attach to the back of it. and i have 2 plugs that i always have to unplug when i take the dash trim off. it appears that my switch has a dummy seat for a plug that has wires/pins in it (fog light plug) i also have the relay in place with pins etc as well as the fuse. this leads me to believe i am already wired for fog lights.

i know ive asked questions about this and there are a ton of posts regarding it so i appologize if this is dumb but this is something i am still learning about.

would i be able to install a 3 prong illuminated switch (ground, feed, power) to the factory fog light wiring, whether by cutting off the plug and connecting the wires to the switch, or another way if there is one.. and then run a power wire from the bottom of that relay to the left fog light, then feed power from that wire to the right fog light? basically, can i plug my aftermarket switch into stock wiring at the dash, then run wires off the factory relay just like i would with an aftermarket relay?

sorry for the wall of text, apologize if this has been answered somewhere, i fail at forum searching =(

i have pictures of my factory plug for fog light switch.