Powertrain Controls - ECM/PCM

DTC 38 - Brake Switch Circuit:

TCC Wiring Circuit:

Circuit Description:

The ECM monitors the status of the brake switch circuits through ECM terminal "BC4".

DTC 38 will set if:
^ No DTC 24 is present.
^ Vehicle speed has been above 35 mph and back to 0 mph 23 times.
^ Status of brake input CKT 420 has not changed state from "applied" to "released" or released" to "applied."

DTC 38 does not illuminate the MIL (Service Engine Soon).

Test Description: Number(s) below refer to circled number(s) on the diagnostic chart.

1. Jumpering the brake switch will determine if the ECM and wiring for the brake circuit are OK.
2. Verifies supply voltage to the brake switch.

Diagnostic Aids:

An intermittent may be caused by a poor connection, mis-routed harness, rubbed through wire insulation, or a wire broken inside the insulation.

Check for:
^ Poor Connection at ECM pin "BC4" or brake switch connector. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection
^ Damaged Harness. Inspect harness for damage. If harness appears OK, observe "TCC BRAKE SW DISPLAY" on Tech 1 while moving related connectors and wiring harness. A change in display would indicate the intermittent fault location.