tail and brake light problem

[grandpastruck]

Help, I have turn signals and headlights, but no reverse, brake or taillights. Meter says I have no signal to the reverse or tail/brake lights at the back or leaving the cab, so presumably not a ground problem (?)

TAILLIGHTS: There’s no power from the light switch to the tail lights. Does that mean the switch is bad—or does power for the taillights depend on a different circuit than the headlights?

When I took the light switch apart everything looked fine—but if I short the light switch connector from the red wire (power for the headlights) to the brown wire (tail/brake light) my tail lights go on.

Where does power for the taillights come from? Is there something I’m missing here?

REVERSE LIGHTS: I haven’t really started to try to figure this out but I do know that little half-moon connector is just hanging loose by the steering column. It’s not clear to me from the shop manual how/whether this should be connected. Perhaps I’m missing the back-up switch entirely? Would this make any difference as far as my brake and tail lights?

[Z-72]

Do you have dash lights? If not check the fuse.

[jim71chevy]

On my 71 chevy it was the turn signal switch in the coloum drove me nuts to find it, mine was doing the same think as yours.

[Longhorn Man]

turn signal switch wouldn't cause the parking lights to not work.
Check your fuse, and if that is good, then you'll need to find the wire going from the fuse box to the light switch.
I believe the same fuse does the tail lights and stop lights, but I may be mistaken on that.

[grandpastruck]

Thanks Longhorn, Z-72.

It was (more or less) the fuse.

For anyone who encounters similar problems, my fuse was good and my multi-meter showed voltage going to the light switch... but only when the switch was in the off position.

Turns out the fuse contacts were sufficiently corroded that when I put a load on the circuit by turning on the switch, the voltage dropped to zero. Very confusing--especially since once or twice everything briefly worked.

I cleaned up the fuse contacts and now everything works great.

[Longhorn Man]

Sweet.
A good way to clean the contacts is a solution of Arm&Hammer baking soda and water. Put it all in a spray bottle and hose it all down. (DISCONNECT YOUR BATTERY FIRST!) The solution eats the corrosion and leaves it pretty darn clean.
If your carpet is nice (unlike mine) I wouold recomend pulling it back first.
Of course, you probably coulda heard this yesterday huh?

[TERRYP]

Make sure the rear harness is connected at the firewall, It is separate with tan, lt and dk green, brown and yellow wires.