Powertrain Controls - ECM/PCM

Diagnostic Chart:

Wiring Diagram:

CIRCUIT DESCRIPTION
The normally closed brake switch supplies a B+ signal on CKT 420 to the PCM. The signal voltage is opened when the brakes are applied.

DTC 38 WILL SET WHEN
^ CKT 420 has constant voltage.
- Vehicle speed is greater than 20 mph for greater than 6 seconds.
- Then vehicle speed is between 5 mph and 20 mph for greater than 6 seconds.
- For a complete total of seven times.

ACTION TAKEN (PCM WILL DEFAULT TO)
^ No Torque Converter Clutch (TCC).
^ No fourth gear in hot mode.

DTC 38 WILL CLEAR WHEN
Fault condition no longer exists.

DTC CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. This test checks for voltage at the brake switch.
2. This test checks the brake switch
3. This test checks CKT 420 at the PCM.

DIAGNOSTIC AIDS
^ Refer to PCM Intermittent Diagnostic Trouble Code or Performance. - Intermittent Malfunctions
^ Check customer driving habits and/or unusual traffic conditions(i.e. stop and go expressway traffic).