Here is how you hook up the fog lights under the dash so that they will A) work like they're supposed to, and, B) not set your car on fire. The picture at top is the end of the tail light harness that is under the dash. The two prong connector is the rear turn signals and it is plugged into something that comes out of the steering column, near the rest of the wires that come out of the steering column for the turn signal switch. The three prong connect is plugged into a matching three prong connector that is part of the under dash harness. Unplug those two connectors in your car and plug in the two three-prong connectors of the fog light under dash harness ( middle picture) with the connector circled in red on the tail light feed plugged into the connector circled in green and indicated by the two yellow arrows in the picture of the fog light underdash harness. Plug the other connector circled in green into the three prong connector in the car's main underdash harness that is still just flapping in the breeze up there. The connector circled in red on the fog light harness plugs into the connector on the fog light switch. The long grey wire goes out through the firewall and the blue wire with the black stripe is attached to a little circuit breaker. The other prong of the circuit breaker has a wire ( supplied by you) that is attached to the back side of the ignition switch. On a real-live, factory GT, (which was what the fog lights came on) that circuit breaker would have been mounted on the big bracket that the pedals are hanging from. It needs to be mounted somewhere, though, and insulated, so that it isn't bouncing around, shorting itself out on stuff as you go down the road. Most folks mount it to the pedal bracket and wrap it up with some electrical tape.
Hi Veronica
ReplyDeleteThanks for your help with my fog
light wiring. Do I have to get to the headlight switch at all or is this the harness that you say is
"flapping around in the breeze?" This is still a bit confusing although your explanation is the best out there! Can you go over this again for me?
Sincerely
Ron Hagopian
You don't have disturb the headlight switch at all to do this, but, you will need to pull the instrument cluster out so that you will have access to the back of the ignition switch and the plug connector for the tail light harness. This isn't a big deal at all, though. I have the instructions for that in a post called Instrument Cluster Removal.
ReplyDeleteOn your car, that three prong connector on the tail light harness will probably be a two prong connector, since your car probably didn't come from the factory with reverse lights. If you look at the three prong connector in the picture, you will notice that one on the wires is black with a red stripe. That's the wire that powers the reverse lights. Since you already have the foglight wiring stuff, you can still make that work if it's the three prong stuff. What you should have is a switch, which also has a three prong connector, a wire harness thingy that has three ends, each of which has a three prong conector, a bunch of light gray wire, a little circuit breaker, and a couple of short black wires that have a ring connector on one end and a bullet connector on the other end.
What you need to do, once you get the instrument cluster out of the way, is install the switch assembly in the dash of the car. Then, locate the flat plug connector that connects the tail light harness to the main underdash harness. It will be kind of up above where the fuse box is, and the end that goes out to the tail lights will go down behind the driver's side kick panel, then under the door scuff plate and on out to the trunk. It should have a woven type wrap aroung it. If you go to the post on headlight switch replacement and click on the second picture, you can see where the taillight harness is on the right hand side of the picture, back behind the windshield wiper switch. It has a green wire with an orange stripe and an orange wire with a blue stripe. Unplug the connector of that harness.
On the harness that you bought that plugs into the fog light switch, two of the connectors will have a black wire with a red stripe running from one to the other. The connector that does not have this wire is the one that plugs into the switch. The two remaining connectors of that harness plug into the the two connectors which you unplugged on the tail light harness. Make sure that the prongs for the black wire with the red stripe aren't plugged into anything, and the other two wires are going color-to-color.
You will also have a long wire coming out of the switch that has a ring connector on the end of it that looks kind of like it should be a ground wire. It isn't. That is the wire that supplies power to the switch when the head lghts aren't on. Attach that to circuit breaker that came with the wiring kit and make you a wire with a ring connector on each end. Connect one end to the other prong on the circuit breaker and connect the other end to the stud on the back of the ignition switch. This will give the foglight switch power when the key is in the on position. The you run the really long grey wire through the firewall and out to the driver's side fog light. Plug the connector which is a female connector and has two wires coming out of it into the drivers side fog light and run the other wire from that connector over to the passenger side fog light and plug it into that. You will have the two short black wires remaining. Plug one each into the other connectors of the fog lights and connect the ring connector from each to the same screws on the radiator core support that has the headlight ground screws on them. One will be by the front of the battery and the driver's side ground screw will be kind of near the voltage regulator.
This seems really great, but what about cars like mine that don't have the three prong connector under the dash? :(
ReplyDeleteAll of the 65/66 cars have either a two or three prong connector, depending on whether or not the back-up light wiring is an integral part of the taillight harness. The connector is the one that connects the taillight harness to the main underdash harness. If you look around up above the fuse box, back behind the instrument cluster, you will find it. Another way to approach this would be to remove the d/s kick panel and trace the taillight harness up to where it plugs into the main underdash harness. That's the connector.
ReplyDeleteHi Veronica
ReplyDeleteCan you possibly help me. Here is the situation. 1966 Convertible (non-GT) with factory backup lights. All light worked properly prior to the install of a GT Fog Lights and correct harness. I did not do the work. A known Mustang shop did.
Here is the problem. Post a proper Fog Light Install all the lights work excepts for the rear turn signals. They come on but flash together in the rear. The fronts work correctly. If the rear is turned on and i come to a stop the brake pedal freezes both lights. If I take my foot off the brake the rear turn signals resume to flash.
Here is what I have eliminated. Grounds are working, bulbs are good, brake light switch is good, two pronged flasher is good, light switch works in all aspects and stages, rear back up lights work, emergency flasher switch and two pronged flashed is working, fog lights work correctly, turn signal switch appears to be working.
Additionally if I unplug the passenger side rear lamp while the flasher is engaged the driver side rear lamp continues to flash.
Any thoughts, have you seen this before, where would you advise looking/testing? If I unplug the fog light harness and re-plug the car harness back to factory is that a ok way to isolate the fog lights? Or do i also have to take the power lead off the ignition switch?
You site and guidance is GREAT.
Thanks in advance for you advice and help.
John
Hello Veronica,
ReplyDeleteThanks for this great information. I have a 1966 coupe that I am finally finishing up. I ordered the fog light kit to add a "GT" look to the car. I understand the wiring from the Fog Lights, however, I did a complete wiring replacement with Painless and hence the factory wiring connectors are not there. I think I will need to splice to connect. Can you tell me what the 3 wires go to on the 3 prong connector? Is there an easier way? Thanks
Paul
Hi Veronica,
ReplyDeleteGreat site and great information. I have a non-GT 1966 coupe that I am restoring and adding the look of a "GT" to the car. I ordered the Fog Light Kit and have replaced all the factory wiring with a painless kit. I understand the instructions except that the 3 prong connector is no longer there because of the new wiring kit. Where do each of the wires on the 3 prong connector go and will I just have to splice them together? Any ideas would be greatly appreciated. Sorry for my ignorance on this issue.
Regards,
Paul
Hi Veronica,
ReplyDeleteGreat site and great information. I have a non-GT 1966 coupe that I am restoring and adding the look of a "GT" to the car. I ordered the Fog Light Kit and have replaced all the factory wiring with a painless kit. I understand the instructions except that the 3 prong connector is no longer there because of the new wiring kit. Where do each of the wires on the 3 prong connector go and will I just have to splice them together? Any ideas would be greatly appreciated. Sorry for my ignorance on this issue.
Regards,
Paul
Hi, Paul. In that three prong connector,there is only one of those three wires that you need to be concerned with. One is for the gas gauge sending unit and one is for the back-up lights. Obviously, those have absolutely nothing to do with some fog lights. The only one that matters is the one for the tail lights, and it is the one that is in the middle of the connector. In the wiring that came with the fog light kit, there will be a wire harness that has three connectors. One plugs into the switch wiring, and the other two interrupt where the tail light harness plugs into the main underdash harness. If you plug the connector into the switch like the instructions say, and then cut the wire that powers the tail lights in the tail light harness, then plug the two ends of the wire you just cut into the middle connectors of the two remaining three wire connectors that are part of the harness that came with the fog light stuff, you should be good to go.
ReplyDelete