Here is a link to the schematic on Tom Collins website,
The brake warning lamp in the speedo is a two wire, black and red, red being 12v and the black splitting and running to the parking brake contact and on to the brake failure switch on the proportioning valve, that circuit appears to return to one of two ignition switch plugs on the column.
One, does the brake failure switch create a ground path for the warning lamp when the brakes fail?
And if that is true, if I jumper the connector located at the bulkhead it should cause the bulb to illuminate, correct?
Two, what happens to the ground that goes back to the ignition switch plug, circuit 57A?
I don't see that 57A continues after that reaching the ignition switch plug.
The problem is the warning lamp does not work if I set the parking brake and it appears the two switches work independently. I did try running a direct ground to the parking brake connector and the bulb didn't illuminate.
I don't have the harness that runs from the failure switch to the connector at the bulk head.