Engine Control Module: Service and Repair

Service of the ECM should normally consist of either replacement of the ECM or a MEM-CAL change. If the diagnostic procedures call for the ECM to be replaced, the Memory-Calibration unit (MEM-CAL) and ECM should be checked first to see if they are the correct parts.

Powertrain Control Module (PCM):

When replacing a production ECM with a service ECM, transfer the broadcast code and production number from the production unit to the service unit. Also, during replacement, the MEM-CAL (PROM) must be removed from the ECM being replaced and transferred to the new unit.

1. Disconnect battery ground cable.
2. Then disconnect two computer electrical connectors.
3. Remove computer mounting hardware.
4. Remove computer from passenger compartment.
5. Reverse procedure to install.

After installing the new MEM-CAL unit enter diagnostics and check for codes. If code B556 is present, the MEM-CAL unit is installed wrong or there are bent pins. If code B556 is set, follow the procedures under DIAGNOSIS AND TESTING PROCEDURES/DIAGNOSTIC CHARTS/TROUBLE CODE CHARTS/BCM TROUBLE CODE CHARTS.