DTC 37 & 38, TCC Brake Switch Stuck On Or Off (1994): Notes

Normally closed brake switch supplies battery voltage signal on circuit No. 420 to PCM/TCM. Signal voltage drops to zero volts when TCC brake switch is opened (brake pedal depressed).

DTC 37 will set when circuit No. 420 is open, vehicle speed is less than 5 MPH for greater than 6 seconds, then vehicle speed is between 5-20 MPH for greater than 6 seconds, then vehicle speed is greater than 20 MPH for greater than 6 seconds. Conditions must occur on 7 different occasions.

DTC 38 will set when circuit No. 420 has constant voltage, vehicle speed is greater than 20 MPH for greater than 6 seconds, then vehicle speed is between 5-20 MPH for greater than 6 seconds. Conditions must occur on 7 different occasions.

For both DTC's, PCM/TCM will default to no TCC and no 4th gear in hot mode.

NOTE: Test numbers refer to numbers on diagnostic chart.

Test Number 1) This test checks for voltage at brake switch.

Test Number 2) This test checks brake switch.

Test Number 3) This test checks circuit No. 420 at PCM/TCM.