Powertrain Controls - ECM/PCM

Code 38 Chart:

Wiring Diagram:

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

Code 38 will set if:

^ No Code 24 is present.
^ Vehicle speed has been above 35 mph and back to 0 mph several (23) times.
^ Brake switch status has not changed from released to applied or applied to released. Code 38 does not illuminate the SES light.

TEST DESCRIPTION:

1. By jumpering the brake switch this will determine if the ECM and the wiring for the brake switch circuit are OK.

2. Verifies the voltage to the brake switch.

DIAGNOSTIC AIDS:

^ A Code 38 in combination with a Code 39 would mean a problem with one or more of the following components. Fuse, CKT 639, brake switch or wire before the splice.
^ A single Code 38 is the result of a wire or CKT 420 problem between the splice and the ECM, poor connection to ECM connector, or possibly the ECM.