FYI FORD MustangSteve's Ford Mustang Forum / 1965 mustang question on Yellow/ Black routing

**Posted by True74yamaha** 5/15/2024 2:46 AM

Curious where the Yellow/ black stripe wire goes after it passes through the firewall? Is Yellow/ Black stripe wire the same as Green/Red stripe charge wire?

Last edited by True74yamaha (5/15/2024 3:06 AM)

**Posted by BobE** 5/22/2024 6:14 AM

The Black-Yellow (#37) enters the interior and is spliced to; the Yellow wire (#21) that goes to the fuse block (#21), and the Black-Orange wire (#25) that goes to the light switch, and to the ignition switch (#37).

No, the Black-Yellow wire (#37) is not the same as the Green-Red wire (#904). The Green-Red wire provides power from the ignition switch to the alternator/regulator when the ignition switch is turned to ‘run’ or ‘start’ position.

**Posted by TKOPerformance** 5/22/2024 6:21 AM

A good rule of thumb in automotive wiring is that a red wire is keyed 12V while a yellow wire is constant 12V. Tracers are typically just used for circuit delineation (i.e. black strip indicates ignition circuit, etc.).

**Posted by True74yamaha** 6/05/2024 10:26 AM

Figured it out yellow/black stripe wire is for alt dummy light. Its on the exterior light harness. I believe its an early harnesses with yellow/ blue stripe horn wire. Later harnesses have green/red stripe for alternator and yellow/ green stripe for horns.

Does anyone here have a 1964 1/2 underdash harness they'd be willing to sell even if it's in horrible shape that's fine I need the firewall connectors.