What is this wire? (1 Viewer)

[MatthewMcD]

While fixing my broken backup light switch I noticed this red wire coming from the same branch of the wiring harness. The two wires on the left are from the switch on the transmission. Does anyone know what this third red wire is for?

 

[locklaw]

If you have a later model (77/78) the third wire could be for the high gear indicator (but it's green), otherwise the third wire could be for the 4wd indicator which was often paired with optional vacuum actuated transfer cases or until late in production (82+). There were options of a light earlier on also and the harness has the wire but it is unused.

In any event, ensure that the third wire is not hot when switched on or if it is, seal the connector well.

 

[MatthewMcD]

If you have a later model (77/78) the third wire could be for the high gear indicator (but it's green), otherwise the third wire could be for the 4wd indicator which was often paired with optional vacuum actuated transfer cases or until late in production (82+). There were options of a light earlier on also and the harness has the wire but it is unused.

In any event, ensure that the third wire is not hot when switched on or if it is, seal the connector well.

This one is a '75 chassis but that's not a guarantee of much else I have found. So it's "mostly '75". I was thinking about the 4WD indicator. I don't see any other switches on the transfer case. This is not a vacuum actuated t-case. I'll test it for voltage and cap it...for now.