Powertrain Control Module (PCM) Replacement
POWERTRAIN CONTROL MODULE (PCM) REPLACEMENTService of the powertrain control module (PCM) should consist of either replacement of the PCM or programming of the electrically erasable programmable read only memory (EEPROM). If the diagnostic procedures call for the PCM to be replaced, the replacement PCM should be checked to ensure that the correct part is being used. If the correct part is being used, remove the faulty PCM and install the new service PCM.
Removal Procedure
IMPORTANT:
- To prevent internal PCM damage, the ignition switch must be OFF when disconnecting or connecting power to the PCM.
- Remove any debris from around the PCM connector surfaces before servicing the PCM. Inspect the PCM module connector gaskets when diagnosing or replacing the PCM. Ensure that the gaskets are installed correctly. The gaskets prevent contaminant intrusion into the PCM.
- The replacement PCM must programmed.
1. Disconnect the negative battery cable.
2. If equipped with the Allison transmission regular production option (RPO) M74, remove the engine harness clip from the PCM cover.
3. Release the PCM cover mounting tabs.
4. Release the PCM cover from the mounting bracket.
5. Remove the PCM cover.
6. Loosen the PCM electrical connector bolts (2).
NOTE:
- Refer to PCM and ESD Notice in Service Precautions.
- In order to prevent internal damage to the PCM, the ignition must be OFF when disconnecting or reconnecting the PCM connector.
7. Disconnect the PCM electrical connectors.
8. Release the spring latch from the PCM.
9. Release the PCM mounting tabs from the PCM.
10. Remove the PCM.
Installation Procedure
1. Install the PCM.
Ensure that the mounting tabs are engaged.
2. Secure the spring latch to the PCM.
3. Connect the PCM electrical connectors.
NOTE: Refer to Fastener Notice in Service Precautions.
4. Tighten the PCM electrical connector bolts (2).
Tighten
Tighten the bolts to 8 N.m (71 lb in).
5. Install the PCM cover.
6. If equipped with the Allison transmission RPO M74, install the engine harness clip to the PCM cover.
7. Connect the negative battery cable.
8. If a NEW PCM was installed, program the PCM. Programming and Relearning
9. Perform the crankshaft position (CKP) system variation learn procedure. Refer to CKP System Variation Learn Procedure. Programming and Relearning
10. If necessary, reset the engine oil life monitor. Refer to GM Oil Life System - Resetting in Maintenance and Lubrication.