Engine Control Module: Service and Repair
PCM Removal And Installation:
PCM Access Cover:
PROM Unit Installation:
PCM And Sensor Ground Locations:
Service of the Powertrain Control Module (PCM) should normally consist of either replacement of the PCM or a PROM change.
If the diagnostic procedures call for the PCM to be replaced, the engine "calibrator" (PROM) and PCM should be checked first to see if they are the correct parts. If they are, remove the PROM from the faulty PCM and install it in the new service PCM.
THE SERVICE PCM WILL NOT CONTAIN A PROM. Diagnostic Trouble Code (DTC) P1623 indicates the PROM is installed improperly or has malfunctioned. When DTC P1623 is encountered, check the PCM installation for bent pins or pins not fully seated in the socket. If it is installed correctly and DTC P1623 still sets, replace the PROM.
CAUTION:
^ To prevent possible Electrostatic Discharge damage to the PCM or PROM, Do Not touch the component leads, and Do Not remove integrated circuit from carrier.
^ When replacing the production PCM with a service PCM (controller), it is important to transfer the broadcast code and production PCM number to the service PCM label. Please do not record on PCM cover. This will allow positive identification of PCM parts throughout the service life of the vehicle.
^ To prevent internal PCM damage, the ignition must be "OFF" when disconnecting or reconnecting power to PCM (for example, battery cable, PCM pigtail, PCM fuse, jumper cables, etc.).
^ The PCM ground must be located on the transaxle to engine stud as shown the image. If the PCM ground was on the "battery" ground stud, a high current ground could create transient sensor values to PCM.
REMOVE OR DISCONNECT
1. Ignition "OFF"
2. Right hand hush panel.
3. Connectors from PCM.
4. PCM from passenger compartment.
5. PCM access cover.
6. PROM.
CAUTION:
^ Replacement PCM is supplied without a PROM, so care should be used when removing it from the defective PCM because it will be reused in the new PCM.
^ Using two fingers, push both retaining clips back away from the PROM. At the same time, grasp it at both ends and lift it up out of the socket. Do not remove the cover of the PROM. Use of unapproved PROM removal methods may cause damage to the PROM or socket.
Inspect
Note position of PROM for proper installation in new PCM.
7. New PCM from its packaging and check the service number to make sure it is the same as the defective PCM.
8. Access cover.
INSTALL OR CONNECT
1. PROM in PROM socket.
A. Align small notches in PROM socket.
B. Gently press down on the ends of the PROM until the clips are against the sides of the PROM.
CAUTION:
^ Do Not press on the ends of the PROM until the clips snap into place. Doing so may damage the PCM and/or PROM.
C. Press inward on clips until they snap into place.
2. Access cover on PCM.
3. PCM in passenger compartment.
4. Connectors to PCM.
5. Right hand hush panel.