Jeep Cherokee Forum - Adding Fog Lights

Sorry, I know this is about a month old, but if you're still looking for advice...

I'm not sure if there is a wiring harness set up from the headlights. When I put mine in, I used a single relay, two inline fuses, and a switch.

I ran a heavier gauge wire, not sure of what it was, probably 8 or 10, from the positive terminal of the battery, to a fuse, to the relay. (30). I also ran a wire to chassis ground from relay (85). (87) Went to an inline fuse to the switch, then to the positive wire of both lights. The negative wires from the lights went to chassis ground. Because I wanted the lights to always turn off when car was off, (because when I originally set this up without a relay, the first thing I did was leave them on when I went to work) I wired (86) to splice the hot wire from the aux. power in the dash. I chose this because it was easy to get to, as the switch was going right next to it. You can use any device that will turn on/off with the car.

This has worked for me. You could also use a second relay so you don't run that extra wire, resulting in some increased resistance, all the way through the firewall and back. Seeing as they are fog lights though, I didn't mind them being a tiny bit dimmer than they could be.

The fuses I used were 35 amp before the relay, as it was a 40 amp relay, and a 15 for the lights themselves, as they were each 55Watt bulbs. Mathematically, 12*I=(55+55), I checked the current with a multi-meter right after the install, and found it to be about 11 Amp draw with the extra resistance of the wire accounted for.

Note: I didn't wire this to shut off when the high beams were turned on. My logic was that even though in many places you're required to turn fog lamps off when turning high beams on, if there was fog, I wasn't going to have my high beams on. It just seemed like an extra bother.

Hope this helps