P
PNewitt
Guest
I thought it was important, with all the previous discussion about taillight wiring, to provide this diagram, and we could have a detailed discussion about how this works--and how to restore the original brightness "the original way". I think Steve (RV Trash) could/should chime in here, too.
Here is the basic way this harness works:
- There are two white plastic connectors that connect to the 14401 Under Dash Harness (just like one in a non-GT/CS '68 Mustang), that provide the power to the taillights. This harness also provides the power to the backup lights, and the license plate light. It runs along the rocker panels of your GT/CS, through the interior quarter panels, and come out into the trunk on the driver's side.
These connectors include two sets of wires (look at the far left of the drawing):
-#5 Orange with a blue stripe, for the RIGHT Brake and Turn Signal Lights
-#9, Green with an orange stripe, for the LEFT Brake and Turn Signal Lights
As you look at these wires, note that they each are split into three parts, for the three (1157) Lamps. A non-GT/CS '68 Mustang uses only one wire here, not split into three separate wires. The added amperage of two more 1157 bulbs can be handled by the gauge of the wire in this harness (higher amperage is provided by the HD Alternator and a bigger under-hood stock type relay).
-#14 Black is the "Parking Elements" wire, that is on when you turn on your parking or headlights. Note that this same wire powers up the license plate light at the same time.
-#140 Black with a red stripe, is ONLY there to power the backup lights, when you engage the shifter switch, whether auto or manual. This wire has nothing to do with the brightness quality of your taillights.
GROUND WIRES : Just right of the Lic. Plate light diagram, you'll see "GND" with three little lines. This indicates the ground wire for the backup lights harness. Next, note at the top of the diagram, the connectors with a wire that comes off the top, with the letters "GND". This indicates the ground wires that are part of the separate Thunderbird taillight harness used for the GT/CS. This harness includes the sockets for the bulbs, AND it has it's own ground wire (THIS can be the culprit for poor lamp brightness, since corrosion and "crud" can get in between the bolt and eyelet and the surface of the metal body that it is secured to).
If you follow the wires "57B", and "57C", you'll see how the ground wire for the backup lights, AND the ground wires off the T-Bird harnesses are common (57 A-B-C all work together, and are black). When you plug in the T-Bird harness to the main harness, you're providing the (negative) common ground for both the backup lights AND the taillights.
Note that the connectors, as drawn are placed like they're pages in a book. If you were to connect them, the left diagram would fold over to connect to the right diagram to match the contacts.
We'll get into the specifics of testing and contact problems next, but first, here is the identification of your harness.
Questions? Comments?
Next, we'll talk about wire gauge, and how to test the continuity of these wires.
Paul N.
Here is the basic way this harness works:
- There are two white plastic connectors that connect to the 14401 Under Dash Harness (just like one in a non-GT/CS '68 Mustang), that provide the power to the taillights. This harness also provides the power to the backup lights, and the license plate light. It runs along the rocker panels of your GT/CS, through the interior quarter panels, and come out into the trunk on the driver's side.
These connectors include two sets of wires (look at the far left of the drawing):
-#5 Orange with a blue stripe, for the RIGHT Brake and Turn Signal Lights
-#9, Green with an orange stripe, for the LEFT Brake and Turn Signal Lights
As you look at these wires, note that they each are split into three parts, for the three (1157) Lamps. A non-GT/CS '68 Mustang uses only one wire here, not split into three separate wires. The added amperage of two more 1157 bulbs can be handled by the gauge of the wire in this harness (higher amperage is provided by the HD Alternator and a bigger under-hood stock type relay).
-#14 Black is the "Parking Elements" wire, that is on when you turn on your parking or headlights. Note that this same wire powers up the license plate light at the same time.
-#140 Black with a red stripe, is ONLY there to power the backup lights, when you engage the shifter switch, whether auto or manual. This wire has nothing to do with the brightness quality of your taillights.
GROUND WIRES : Just right of the Lic. Plate light diagram, you'll see "GND" with three little lines. This indicates the ground wire for the backup lights harness. Next, note at the top of the diagram, the connectors with a wire that comes off the top, with the letters "GND". This indicates the ground wires that are part of the separate Thunderbird taillight harness used for the GT/CS. This harness includes the sockets for the bulbs, AND it has it's own ground wire (THIS can be the culprit for poor lamp brightness, since corrosion and "crud" can get in between the bolt and eyelet and the surface of the metal body that it is secured to).
If you follow the wires "57B", and "57C", you'll see how the ground wire for the backup lights, AND the ground wires off the T-Bird harnesses are common (57 A-B-C all work together, and are black). When you plug in the T-Bird harness to the main harness, you're providing the (negative) common ground for both the backup lights AND the taillights.
Note that the connectors, as drawn are placed like they're pages in a book. If you were to connect them, the left diagram would fold over to connect to the right diagram to match the contacts.
We'll get into the specifics of testing and contact problems next, but first, here is the identification of your harness.
Questions? Comments?
Next, we'll talk about wire gauge, and how to test the continuity of these wires.
Paul N.