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Home >> GMC >> 1995 >> Forward Control 7.4 N >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes - 7.4L >> Trouble Code Charts >> Codes 37/38, TCC Brake Switch On/Off >> Notes
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Codes 37/38, TCC Brake Switch On/Off: Notes

The normally closed brake switch supplies battery voltage to control module. 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 control module.