When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
While dismantling my dash on my 75 C3, I finally removed nearly everything from up front checking my heater box, I decided to go all the way and find out what kind of strange things I would find and at the same time I could clean this thing up and organize the wires better, check the heater box vacuum system, lube up the cables…etc…but I found these strange wires behind the dash, right above the fuse box, wires are cut and I have no idea what this went to? Anybody here know what this is or once was. The engine is a crate 350, the original engine has been long since replaced.
Sorry for the late response to your question. I had to do some digging before I replied. Here is the answer to your question:
The Light gray wire with the black connector on the left is an unused connector coming off of the UF-1 Map Light Mirror harness. (yellow arrow)
The dark gray wire in the middle is the power feed to your UF-1 Map Light mirror. (blue arrow)
The tan wire with the green connector (red arrow) on the right plugs into the LPS socket on your fuse panel. It supplies a signal to the new for 1975 headlamps-on buzzer (purple arrow below),
None of this info is contained in the wiring diagrams that appear in the 1975 Chevrolet Service and Overhaul Manual Supplement. In addition, the wiring details for this as shown in the 1975 AIM are incorrectly labeled and incomplete.
This fuse panel pic (below) is from my 1975. Tan wire with the green connector is shown plugged into the LPS socket and the Headlamps-on buzzer (purple arrow) is shown.
A while back I pulled a wiring harness out of another 1975. Below are some pics. Colored arrows correspond to above.
Note that the tan wire with the green connector is missing from this harness.
The pic below is roughly how this wiring harness would be oriented in your car.
The tan wire with the black connector (green arrow) plugs into the IGN socket on the fuse panel. This provides the power for the Headlamps-On Buzzer, UF-1 Map Light Mirror (if equipped) and C-50 Rear Window Defogger (if equipped).
Here is a closeup of the Headlamps-On Buzzer
The as-installed part number is 344835. SERVICE part numbers are 364079 and possibly 364080
Strange wires
