Whats this wire for?
 

On my wiring harness, at the firewall junction, on the top row. One Red , one black, one black with white stripe. I know what the red and the black with white stripe are for but what about black? It's not in my wiring diagram. Its a 72 harness.

AND after doing the removal of external regulator, I should get a complete circuit from the tan wire in the harness to the white wire going to the alternator, correct? (when using a tester)

isn't black usually ground?

In the wiring diagrams the ground wires for the headlight harness splice into a dark blue on one side and go straight to ground on the other side. This black wire begins right at the firewall connector and i have no idea what it connects to or where it goes.

Anyone help? My manual doesn't show 72 wiring diagram.

Hey 72gmcshorty the black wire goes to the junction block on the pass side finder and connects with the pos side of the battery.
http://www.geocities.com/chevroletc1070/v8engcomp.html ...


Chuck

black with whit stripe is for the ammeter guage it should have a fuse in it at the radiator support on either corner. that's how i chased it in the 70 chassis service manual

Thanks for the link. Any idea what size fuse is needed and what this wire is for?

4 amp

I mean the pure black wire. Not the one for the gauge

Both wires for the amp gauge take 4 amp fuses.

There's 2 wires for the gauge? Now you have me confused. I know the black wire with white stripe has two inline fuses at 4 amps each. I'm sure this wire is for the gauge. I need to know about the solid black wire that is located right next to the black/white stripe wire on the firewall junction of the harness. In the diagram from the link above it shows the Black wire and the B/W wire as both having inline fuses. What size fuse is in the other wire? Look at the picture and you'll see what I mean.

The black wire that goes to the junction block takes a 4 amp.
the black w/ white stripe and the black going to the junction block are both for the amp gauge.