Envoy 4WD V8-5.3L VIN M (2005)
Engine Control Module: Service and Repair
Engine Control Module (ECM) Replacement
ENGINE CONTROL MODULE (ECM) REPLACEMENT
Service of the engine control module (ECM) should consist of either replacement of the ECM or programming of the electrically erasable programmable
read only memory (EEPROM). If the diagnostic procedures call for the ECM to be replaced, the replacement ECM should be checked to ensure that the
correct part is being used. If the correct part is being used, remove the faulty ECM and install the new service ECM. The replacement ECM must be
programmed.
Removal Procedure
1. Using a scan tool, retrieve the percentage of remaining engine oil. Record the remaining engine oil life.
IMPORTANT: It is necessary to record the remaining engine oil life. If the replacement module is not programed with the remaining engine oil life,
the engine oil life will default to 100%. If the replacement module is not programmed with the remaining engine oil life, the engine oil will need to be
changed at 5000 km (3,000 mi) from the last engine oil change.
2. Disconnect the negative battery cable.
3. Disconnect the cooling fan electrical connector for additional clearance while removing the ECM.
4. Depress the ECM/transmission control module (TCM) cover retainers (2).
5. Remove the ECM/TCM cover from the ECM/TCM bracket (1).
6. Disconnect the ECM electrical connectors (2) from the ECM (1)
IMPORTANT: It is not necessary to disconnect the ECM electrical connectors in order to remove the ECM from the ECM/TCM bracket. Only
disconnect the electrical connectors if servicing of component requires disconnecting of the electrical connectors.
