Stoplight Switch Circuit

Ensure stoplights operate when brake pedal is pressed. DO NOT  disconnect ABS ECU connectors. Backprobe connectors to measure voltage. On TRAC equipped vehicles, measure voltage between ground and terminal No. 10 on connector A25. On non-TRAC equipped vehicles, measure voltage between ground and terminal No. 7 on connector A23. If battery voltage is present, stoplight switch circuit is okay. If battery voltage is not present, inspect and repair circuit between stoplight switch and ABS ECU. If circuit is okay, replace ABS ECU.