Chart 7A-20A-3: Stop Lamp Switch Circuit

Diagnostic Chart:

Stop Lamp Switch Circuit:

Circuit Description:
When the brake pedal is depressed, a signal is received at the PCM. When this signal is received, indicating that the brakes are being applied, the PCM interrupts TCC lockup to prevent the engine from stalling.

Test Description: Numbers below refer to circled numbers on the diagnostic chart.

1. This tests to see if the vehicle stop lamps operate normally.

2. This checks for an open in GRN/WHT wire or for a faulty PCM.

Diagnostic Aids:
Check STOP Fuse for opens. If the vehicle stoplamps remain lit with the brake pedal released, check for a short to voltage in GRN/WHT wiring between stop lamp switch, PCM and all stop lamps.

Check for poor connections at component and inline harness connector terminal connections before replacing components. After repairs have been made, repeat the PCM OBD System Check to ensure system is functioning normally.