Packard Forum Index » Pre-War (1899-1942)

At this point, the next step is as others have stated. Do you have a voltmeter? If so, remove the jumper you installed. Then, you need to measure the voltage from one terminal of the brake lights switch to ground. If it is at 6V, then that is your “hot” to the switch. If you don’t have 6V, then measure the voltage from the other terminal of the switch to ground. Again, if it is 6V, then it is your “hot” terminal.

At this point, only one terminal should measure 6V, but one terminal should read 6V. If you don’t have 6V at either terminal, then you have a wiring problem prior to switch.

If one terminal does have 6V, and we know that the switch is not the problem, then you have a wiring problem after the switch.

Once you determine if the problem is before or after the switch, we can start the next steps of the troubleshooting.

No need to remove the jumper for that measurement. There is either power or there isn't so whether the jumper is connected (both terminals should have power) or it's not (one terminal will have power) the test is the same.

Agreed, I just recommended to do that to follow best practices in trouble shooting. That is to work with as few “changes” as possible at one time. The first step was the jumper to see if the problem was the switch. That let us conclude that the switch is not the problem. Best practices is to then return the system back to baseline, Then, take the next step.