Tach wiring

[VS29U1]

I have an old Chrysler parts 3004195 tach. It has 4 wires, black, white, orange, blue. The blue wire is a little thicker. Where are the wires connected to?
TIA, John

 

[Syleng1]

Not sure if this helps as I don’t know that tach:
Most tach from that era need 3 wire to run. Ground, key on power and trigger. Then one for the internal light that connects to the dash lights.

If I had to take an educated guess-
Black or white is ground and key power
Orange is dash light and blue is trigger

 

[Murray]

Pictures.

 

[VS29U1]

Tach pics

 

[Murray]

This is a over-the-counter unit , not available in a factory car. Made by Dixco. Check their wiring.

 

[33IMP]

Dixco wiring shows black, white, red, and green
I'd bet your orange is their red, and your blue is their green
So, slightly educated guess:
Blue to coil neg
Orange to 12v
Black to grnd
White to instrument lights
I am NOT responsible for wiring errors, this is a GUESS!!

 

[cudamark]

My guess is black=ground, white=12V+, orange=light, and blue is distributor negative terminal on the coil. I'd research it to make sure though.