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Home >> GMC >> 1994 >> C3500 HD 6.5 F, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes - Electronic Transmission >> Trouble Code Charts >> Codes 37/38, TCC Brake Switch On/Off >> Notes

Codes 37/38, TCC Brake Switch On/Off: Notes

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.
  1. Checks if voltage is available at brake switch.
  2. Checks brake switch function.
  3. Checks circuit from brake switch to PCM.