These switches have two types of contacts in them, normally closed and normally open. The brake lights hook to the normally open switch so that when brakes are applied the lights come on. The TCC is on the normally closed position which feeds 12 V to the torque converter lock up solenoid. When you apply the brakes the TCC solenoid is disconnected from power so that the torque converter wont fight the brakes. The ground side of the solenoid is driven by the ECM which pulls it low to lock up the TCC. I would check to see that you have it hooked up properly and that the push button is moving properly with the brake pedal in both the on and off positions.
DaveB - I appreciate the feedback and detailed operation. I had an idea of how it worked but your description made it clear. I tested the open and closed positions with a test light. I updated the previous posted sketch and added labels. The way I currently have it wired is:
1 = TCC (Purple wire / Pin33)
2 = 12V+ (constant positive)
3 = Keyed switch (12+ when ignition is on)
4 = Brake lights
KEY ON
With the switch pressed in (Brake off) - 1 (TCC) shows closed circuit
With the switch out/released (Brake on) - 4 (brake lights) are closed circuit
Everything seems to be working right however, my brake lights on the jeep don't come on when the pedal is pressed (switch button out), but the switch is working properly?
