Brake Signal: Testing and Inspection

Brake Signal Circuit Check:

Brake Signal Circuit:

Circuit Description:
The normally closed brake switch supplies a 12 volt signal on CKT 420 to the PCM. The signal voltage is opened when the brakes are applied. An incorrect brake signal can affect TCC operation.

Test Description:
Number(s) below refer to circled number(s) on the diagnostic chart.

1. This test checks for voltage at brake switch.
2. This test simulates brake switch closed or brakes OFF."
3. This test checks CKT 420 from brake switch to PCM.
4. This test opens CKT 420 and simulates brakes being applied.

Diagnostic Aids:
^ Refer to PCM Intermittent Diagnostic Trouble Codes or Performance."

^ Check customer driving habits and/or unusual traffic conditions (i.e. stop and go expressway traffic).