For history; about 8 months ago both the brake light switch and the signal switch were replaced. Now, the brake lights on my 68 are not working again.

When the brakes are applied, I get voltage on the white wire from the brake light switch when measured at the connector to the turn signal (TS) switch if the connector is unplugged. When I plug the TS connector back in there is no voltage reading. I am assuming from this that the problem is not in the brake light switch or wire up to the TS switch.

With the TS switch connector unplugged, when I jump a hot wire to the terminal on either the green or yellow wire that goes from the connector back to the taillights, I get a brake light on which ever side I am jumpered to. I am interpreting this to mean the problem is not downstream from the TS switch connector.

With the connector unplugged, when I jump the white wire terminal directly to either the green or yellow wire terminals, I do not get any brake lights. The white wire is showing voltage until I jump it to the green/yellow terminal then it goes dead. I don't know how to interpret this.

I am guessing that the problem is with the TS switch but don't understand not getting voltage across the connector on the white wire when the connector is plugged in or why I get nothing when I jump the white wire terminal to either the green or yellow wires which are on the same side of the connector which go to the taillights.

 

Willcox, Can you help this guy? Thanks, Lou.

 

The white wire comes from the brake light switch? White wire has power from the brake light switch as long as it has no load, but does not have power with load? If the power side of the brake switch has power regardless, then the brake light switch is the problem. Put a test light on the brake light fuse and see if the power drops out on either side when you push the brake. Maybe a poor connection at the fuse.