Brake Warning Light Testing

[sprdv1]

Thought I'd report the end result. Today I tested the quality of the switch body to dash ground by turning on the ignition and then grounding the wire directly to the switch body. Light came on as it should. So I was thinking I must somehow have 2 bad ignition switches.

In the process of testing that theory, I had the ignition switch hanging below the dash so I could switch back and forth between them. While doing this, I did not connect the ACC wire to the threaded stud on the back so I could plug and unplug quickly. And I found that with the ACC lead disconnected, the warning light never came on at all, even when manually grounding either of the wires.

Turns out that in the total wiring replacement process, I powered the warning light circuit from an ACC switched source. And the ignition switch is designed to not only ground that spade on the side during cranking, it also cuts power to the ACC circuits (radio, etc.) during cranking.

So when I switched to START, it grounded the spade just fine, but it also killed the power to the light as well. This even explains why I once or twice thought I saw a quick flicker at the warning light. Sometimes the ground might complete the circuit a fraction of a second before it killed the power.

Moving the warning circuit to an IGN switched source fixed it.

Nicely done