Rear Light Wiring for GT

[markandson]

I am connecting all the wires in the tail of my GT and have come across a wire that is not shown on the schematic. On the left side of the car there are two wires, both white/black stripe that are crimped into one female connector. On the right side of the car there is one wire white/black stripe. I believe the single wire is for the backup light, if so, what are the pair of wires on the left side of the car for?

[ungermm]

The single white with black stripe is for the backup light. Might the one in question be the gray with black stripe pair?

[markandson]

I realized what the wire is shortly after I made the post. My GT harness is from a '73 which had TWO back up lights, one in the center of each rear light. The lights I am using are early lights with no backup light. The backup light is a single unit in the center of the rear, so only one wire is needed. I am just capping off the extra wire.

[Dale .D]

I'm having a similar problem with my rear lightes.I chromed the bumperetts & replaced some lenses & all the bulbs.Every thing is working except that when I put on the brakes the left brake light goes out.I've anilized the wiring diagram for my 71 gt & a couple wires have me puzzeled.This is the left stop light..The diagram shows a double blackyellow & a gray black.What I have is a single blackyellow & a double grayblack ?The only area that could be the greyblack double is the lr side marker.Tried that & it made things really mixed up & had to really pull the wire so it didn't feel like the right fit anyway.I know this sounds confusing but I'm running out of possible solutions. Is there a mistake in the diagram . More than likely me I'm sure.All bulbs & fixtures are in perfect working order/ Help

[markandson]

Originally Posted by Dale .D I'm having a similar problem with my rear lightes.I chromed the bumperetts & replaced some lenses & all the bulbs.Every thing is working except that when I put on the brakes the left brake light goes out.I've anilized the wiring diagram for my 71 gt & a couple wires have me puzzeled.This is the left stop light..The diagram shows a double blackyellow & a gray black.What I have is a single blackyellow & a double grayblack ?The only area that could be the greyblack double is the lr side marker.Tried that & it made things really mixed up & had to really pull the wire so it didn't feel like the right fit anyway.I know this sounds confusing but I'm running out of possible solutions. Is there a mistake in the diagram . More than likely me I'm sure.All bulbs & fixtures are in perfect working order/ Help

The double gray black is the marker lights for the side markers and the rear tail light. The single black yellow is for the stop light. Make sure your grounds are all good. And what do you mean by the statement "when I step on the brakes the left light goes out"? Do you mean the tail light goes out, because when you step on the brakes lights are supposed to come on, and not already be on???

[namba209]

Originally Posted by markandson The double gray black is the marker lights for the side markers and the rear tail light. The single black yellow is for the stop light. Make sure your grounds are all good. And what do you mean by the statement "when I step on the brakes the left light goes out"? Do you mean the tail light goes out, because when you step on the brakes lights are supposed to come on, and not already be on???

Jeff I've seen that a bunch of times on cars with Baja license plates on them. Usually it's because the wires were switched when the lites were re-installed. It's easy to figure out, the tail lites kinda sorta act like the ammeter lite in the gauge, the ground through the other lite goes away when you step on the brake and put system voltage across both sides of the lite. For the problem mentioned, check the wires with a VOM to be sure there's power to the brake side of the lite when you step on the brake pedal, and as said before double check the ground wires at each lite.

[Dale .D]

Originally Posted by markandson The double gray black is the marker lights for the side markers and the rear tail light. The single black yellow is for the stop light. Make sure your grounds are all good. And what do you mean by the statement "when I step on the brakes the left light goes out"? Do you mean the tail light goes out, because when you step on the brakes lights are supposed to come on, and not already be on???

When all the lights are on & I press the brake the left brake light goes out but the right gets brighter as it should.itried the double gray black on the left side marker & things went all screwy.I'll have to get in there again& take acloser look . I'm just real close & don't want to bugger things up.

[markandson]

The wiring back there is actually very simple, you only have markers, brakes, backup, blinkers, and a couple of wires that go through the harness and then connect to a short wire that goes to the dome lamp. I drilled two holes and installed two stainless steel screws as good grounds inside the car right behind the gas tank. I ran all my grounds to the two studs, one on the left and one on the right, I ground off the paint and then used dielectric grease to make a good connection and also inhibit rust. If you have to you can disconnect the + at the battery, pull the connectors out of the fuse box and then run a test wire from the positive of the battery and touch it to the proper terminals in the fuse box connectors, then all the lights can be tested, it becomes very simple because all the wires run straight to the back of the car, that is how I did it a few weeks back when I was doing my electrical system. When I plugged in the dash everything worked the first time . Just follow the schematic to determine which terminals do what.

[Dale .D]

Originally Posted by markandson The wiring back there is actually very simple, you only have markers, brakes, backup, blinkers, and a couple of wires that go through the harness and then connect to a short wire that goes to the dome lamp. I drilled two holes and installed two stainless steel screws as good grounds inside the car right behind the gas tank. I ran all my grounds to the two studs, one on the left and one on the right, I ground off the paint and then used dielectric grease to make a good connection and also inhibit rust. If you have to you can disconnect the + at the battery, pull the connectors out of the fuse box and then run a test wire from the positive of the battery and touch it to the proper terminals in the fuse box connectors, then all the lights can be tested, it becomes very simple because all the wires run straight to the back of the car, that is how I did it a few weeks back when I was doing my electrical system. When I plugged in the dash everything worked the first time . Just follow the schematic to determine which terminals do what.

Good Idea on testing the ground wires.I'll get back there again this week end & double check every wire . Thanks from the great white north

[namba209]

To help you out on tracing the wires, Here's the color codes for the rear lites from my DESTEC schematic.

Left Parking Lites: Gray/Black
Left Turn Lite: Black/White
Left Brake Lite: Black/Yellow
License Plate Lite: Gray/Green
Back-up Lite: White/Black
Right Parking Lites: Gray/Red
Right Turn Lite: Black/Green
Right Brake Lite: Black/Yellow

Just to clarify one thing, only the brake lites have a dual element bulb, they should have the pins on the sides of the bulb offset so they can only be installed one way. You may want to double check the connections on those lites to be sure you have the right wire on the correct terminal. HTH.