Engine Control Module: Service and Repair

Electronic Control Module (ECM):

Mem-Cal Socket:

Mem-Cal Install:

Service of the Engine Control Module (ECM) should normally consist of replacing the ECM or an Engine Calibrator (Mem-Cal) change. If the diagnosis calls for the ECM to be replaced, the MEM-CAL and ECM should be checked first to see if they are correct parts. If they are, remove the Mem-Cal from the faulty ECM and install it in the new (service) ECM.

NOTE: The new ECM will not contain a Mem-Cal.

Trouble Code 51 indicates the Mem-Cal is installed improperly or has malfunctioned. Check ECM installation for bent pins or pins not fully seated in socket. If it is installed correctly and Code 51 still shows, replace Mem-Cal.

NOTE: When replacing the production ECM with a service ECM, it is important to transfer the Broadcast code and production ECM number to the service ECM label. This will allow positive identification of ECM parts throughout the life of the vehicle. DO NOT record on ECM cover.

NOTE: To prevent internal ECM damage, the ignition must be OFF when disconnecting or reconnecting power to ECM ( for example battery cable, ECM pigtail, ECM fuse, Jumper cables, etc.)

REPLACEMENT
- Disconnect negative battery cable.
- Remove glove compartment.
- Disconnect connectors from ECM.
- Remove ECM mounting hardware.
- Remove ECM from passenger compartment.
- Remove ECM access cover.
- Remove Mem-Cal.

NOTE:
- Replacement ECM is supplied without a Mem-Cal. Use care when removing it from the defective ECM, it will be reused in the new ECM.
- Using two fingers, push both retaining clips back away from the Mem-Cal. At the same time grasp it at both ends and lift it up out of the socket.
- DO NOT remove the cover of the Mem-Cal. Unapproved Mem-Cal removal may damage the Mem-Cal or socket.

- Inspect Mem-Cal For alignment notches and carefully set it aside.
- Remove new ECM from its packaging and check the service number to make sure it is the same as the defective ECM.
- Remove access cover.
- Install Mem-Cal in Mem-Cal socket.

NOTE: 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.

- Install access cover on ECM.

- Install ECM in passenger compartment.

- Reconnect connectors to ECM.


FUNCTIONAL CHECK
- Turn ignition ON.
- Enter diagnostics.
- 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.
- 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: Before starting engine, follow the "Idle Learn Procedure."
Any time the battery is disconnected, the programmed position of the Idle Air Control (IAC) valve pintle is lost, and replaced with a "default" value. To return the IAC valve pintle to the correct position, perform the following procedure:

- Restore battery power.
- Connect Tech I "Scan" tool.
- Select "IAC SYSTEM," then select "IDLE LEARN" in the "MISC TEST" mode.
- Proceed with idle learn as directed.

This procedure allows the Electronic Control Module (ECM) memory to be updated with the correct IAC valve pintle position, for the vehicle, and provide a stable idle speed