Brake Signal Circuit Check: Notes
WARNING: This page does not describe the selected car, but rather 24 other vehicles, including the 1992 GMC Yukon, 1992 GMC Vandura Special, 1992 GMC Vandura, 1992 GMC Value Van, and 1992 GMC Suburban. However, it is still accessible from the selected car via links, so may be relevant.
The normally closed brake switch supplies a 12-volt signal on circuit No. 420 to the PCM/TCM. The signal voltage is removed when brakes are applied. An incorrect brake signal may affect TCC operation.
NOTE:
Test numbers refer to test numbers on diagnostic chart.
- This test checks for voltage at brake switch.
- This test simulates closed brake switch (brakes off).
- This test checks circuit No. 420 from brake switch to PCM/TCM.
- This test opens circuit No. 420 and simulates condition of brakes being applied.