Engine Control Module: Service and Repair

Computer:

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, the PROM, CALPACK, and if equipped, the MEMCAL must be removed from the Computer being replaced and transferred to the new unit. Refer to MEMCAL in this section for replacement procedures.

1. Disconnect battery ground cable.
2. Coolant tank reservoir.
3. ECM mounting hardware.
4. Connectors from the ECM.
5. ECM from the engine compartment.
6. Remove the ECM access cover.
7. Remove the MEM-CAL.
8. Remove the new ECM from its packaging and check the service number to make sure it is the same as the defective ECM.

INSTALLATION:

1. Install the MEM-CAL in the MEM-CAL socket.

CAUTION: Press only on the ends of the MEM-CAL. Small notches in the MEM-CAL must be aligned with the small notches in the MEM-CAL socket. Press on the ends of the MEM-CAL until the retaining clips snap into the ends of the MEM-CAL. DO NOT press on the middle of the MEM-CAL, only on the ends.

2. Install the access cover on the ECM.
3. Install the ECM in the engine compartment.
4. Connect the electrical connectors to the ECM.

FUNCTIONAL CHECK:

1. Turn the ignition ON.
2. Enter diagnostics.
a. Code 12 should flash four times (If no other codes are present). This indicates the MEM-CAL is installed properly and the ECM is functioning.
b. If Trouble Codes 41, 42, 43, 51, or 55 occur, or if the "Service Engine Soon" light is ON constantly with no codes, the MEM-CAL is not fully seated or is defective.
^ If not fully seated, press firmly on the ends of the MEM-CAL.
^ If it is necessary to remove the MEM-CAL, follow the previous removal instructions.

NOTE: The system has a learning ability which allows it to make corrections for minor variations in the fuel system to improve driveability. When the battery is disconnected the computer's memory is cleared and the learning process has to begin all over again. A change may be noticed in the driving performance of the vehicle. To reset the vehicles learning ability, make sure the engine is at operating temperature and operate the vehicle at part throttle, moderate acceleration, and idle conditions, until normal performance returns.