Electronic Spark Control Module: Service and Repair

Engine Control Module Installation:

CAUTION:
- When replacing a production Computer with a service Computer, transfer the broadcast code and production number from the production unit to the service unit. Also during replacement, knock sensor module must be removed from the computer being replaced and transferred to the new unit.

NOTE:
- These units do not have a replaceable PROM. An Electronically Eraseable Programmable Read Only Memory (EEPROM) is built into the ECM. The EEPROM may be a photo-sensitive type (program will be erased if exposed to light). These units must be programmed using General Motors "TECHLINE" terminal equipment. The replacement ECM is supplied without an EEPROM program. If this equipment is not available for your use, DO NOT attempt to replace ECM.


REMOVE OR DISCONNECT
- Disconnect battery ground cable.
- Coolant reservoir.
- ECM mounting hardware.
- Connectors from the ECM.
- ECM from the engine compartment.
- Remove the new ECM from its packaging and check the service number to make sure it is the same as the defective ECM.
- Access cover from ECM.

CAUTION: Do not remove any screws other that those retaining the access cover.

Removing/Replacing Knock Sensor Module:

Knock Sensor Module - Removing From PCM:

- Remove knock sensor module from ECM (see illustration).



INSTALL OR CONNECT
- Install knock sensor module into ECM (see illustration).
- Access cover on ECM.
- ECM into the engine compartment.
- Connectors to the ECM.
- ECM mounting hardware.
- Coolant reservoir.
- Reconnect battery ground cable.


FUNCTIONAL CHECK:
1. Turn the ignition ON.
2. Enter diagnostics.
^ Code 12 should flash. This indicates the ECM is functioning.