Powertrain Controls - ECM/PCM

Code 38 Chart.:

Code 38 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 (23) times.

^ Status of CKT 420 has not changed state "HI" to "LO."

^ Code 38 does not illuminate the "Service Engine Soon" light.

TEST DESCRIPTION:


1. Jumpering the brake switch 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 439, 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.