Codes 37/38, TCC Brake Switch On/Off: Notes
WARNING: This page does not describe the selected car, but rather 10 other vehicles, including the 1994 GMC Yukon, 1994 GMC Suburban, 1994 GMC Pickup, 1994 GMC Cab & Chassis, and 1994 GMC C3500 HD. However, it is still accessible from the selected car via links, so may be relevant.
The normally closed brake switch supplies battery voltage to the PCM. Signal voltage will drop to zero volts when brake pedal is applied.
NOTE:
Test numbers refer to numbers on diagnostic chart.
- Checks if voltage is available at brake switch.
- Checks brake switch function.
- Checks circuit from brake switch to PCM.