Powertrain Control Module (PCM) Replacement

Powertrain Control Module:

PCM And Prom:

Service of the Powertrain Control Module (PCM) should normally consist of either replacement of the PCM or a Programmable Read Only Memory (PROM) change. If the diagnostic procedures call for the PCM to he replaced, the 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) 51 indicates the PROM is installed improperly or has malfunctioned. When DTC 51 is obtained, check the PCM installation for bent pins or pin not fully seated in the socket. If it is installed correctly and DTC 51 is still displayed, replace the PROM.

CAUTION:
^ To prevent possible electrostatic discharge 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 ignition should be "OFF" for at least 30 seconds before disconnecting power to the PCM.

NOTE: When replacing the production PCM with a service PCM, a DTC 88 will be stored. It is important to program TDC Offset into the service PCM. Refer to TDC Offset Program Procedure. TDC Offset Program Procedure

REMOVE OR DISCONNECT
1. Negative battery cable.
2. Connectors from PCM.
3. PCM mounting hardware.
4. PCM from passenger compartment.
5. PCM access cover.
6. PROM.

PROM REPLACEMENT
1. Powertrain Control Module (PCM) access cover.
2. PCM access cover.

CAUTION: Replacement Powertrain Control Module (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.

3. Using two fingers, grasp the PROM 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
For alignment notches of the PROM and carefully set it aside.

4. New PCM from its packaging and check the service number to make sure it is the same as the defective PCM.
5. Access cover.

INSTALL OR CONNECT
1. PROM in PROM socket.

^ Gently press down on PROM.

2. Access cover on PCM.
3. PCM in passenger compartment.
4. Connectors to PCM.

FUNCTIONAL CHECK
1. Turn ignition "ON."
2. Enter diagnostics mode.

A. DTC 12 should flash three times (if no other DTCs are present). This indicates the PROM is installed properly, and the PCM is functioning.
B. If DTC 51 occurs, or if the Malfunction Indicator Lamp (MIL) (Service Engine Soon) is "ON" constantly with no DTC(s), the PROM is not fully seated or is defective.

^ If not fully seated, press firmly on the ends of the PROM.
^ If it is necessary to remove the PROM, follow the previous removal instructions.