GT / Cobra Fog Light Re-wire.
Written by Mustangworld.
NOTE: Wiring your fog lights to work independently may be illegal in your state. You may also be ticketed when running on the road in this configuration.
We've been getting tons of email about how to get your fog lights re-wired to run independently of your main lights. Well, here we will show you a few different ways to do this. We posted this mainly to clear up some confusion we've seen posted on the web.
OK... HERE WE GO!
First a brief wire description of the harness for '96 GT (may be different for your stang year):
in the fog light harness, there are 2 sets:
2 little metal head wires, Black=12vt ground for the little light on the switch itself, Blue (with red stripe)=12vt Positive for the little light on the switch itself.
The only way we recommend wiring your fog lights for independent operation is by cutting the main power lead (red wire with black stripe) capping it off and running a new switched lead power source from the ignition fuse system or running a non-switched lead from the main battery terminal to the fog switch. This is the safest way to do it and THE ONLY WAY you will get "true" independent operation of your fog lights. To find a new powersource, you'll need a 12vt test light and poke around for a switched 12vt lead, then test which fuse system it goes to (to insure you don't overload it).
The second way is to swap the positive lead wires within the harness itself (switching the Main fog positive lead (red wire with black stripe) with the accessory light power source (blue wire with red stripe). We don't recommend this for several reasons:
1) You DO NOT get true independent operation of your fog lights when swapping the wires, true you can turn your fog lights on independently from your main lights but only if your light knob is in the parking light position (first click out). So you will have your fog lights on and your 2 yellow lights (blinkers) above on as well. Which looks more like you burnt out your headlights while driving. Not to mention your rear brake/riding lights being on as well AND your dash lights will be on also (not too good for Cobra drivers white face gauges at twilight).
2) By switching the main Fog lead with the accessory lead, you take the fog lights off it's fuse. We like keeping the fog lights on it's own fuse. This can be real confusing when your dash and interior lights blow because of a problem with your fog lights. Try not to mix fuse systems in your stang, you can cause major electrical problems if you do. Put heavy load items on heavy load fuse systems within your stang.
3) It's not any easier to do this. In most stangs (not all) the metal wire plugs inside the harness are different sizes and won't simply push back into the harness. You'll still need to cut the wires (or re-fit the connectors) for a perfect fit and to prevent all risks of arching. You can see the size difference in the photo above.
So the simple answer to getting your fog lights to run independently from your main lights (and the only one we recommend) is to run a new powersource to the positive lead on your fog light switch.
You can also wire it up like the article sent in to us by Brian Carr. Located here. This method uses the convertible top switched power lead which is on a heavy load fuse and should be safe to power your fog lights. The convertible top harness exists in the coupe model as well BUT some newer Mustang coupes may not have this harness. All convertibles do.
But don't take our word on it, if you know what you are doing, wire it up any way you see fit ;-)
Til next time... see ya on the street!.