EPROM Flashing

Powertrain Control Module (PCM) and Flashing The EPROM

Important: The service PCM will not contain data. The EPROM must be flashed after the service PCM is installed.

This powertrain has very complex components with equally complex operating characteristics. Therefore, it is essential that the Powertrain diagnostic procedures given in this and other service manual sections be used for diagnosis before any repairs are made. While the PCM may appear on the surface to be the source of a problem, it may, in fact, be operating properly based on incorrect inputs it receives. Powertrain diagnostic procedures are designed to arrive at the CORRECT repair as QUICKLY as possible. DO NOT, under any circumstances, replace a PCM unless directed to do so by diagnostic procedures in the service manual, other service information sources, or through technical assistance.

Service of the PCM will consist of either replacement of the PCM and flashing the EPROM. If a diagnostic procedure calls for the PCM to be replaced, the PCM should be checked first to see if it is the correct part. The EPROM can also be flashed when called for. When flashing the EPROM, also refer to the latest service publications for updated programming procedures and information.

After replacement of a PCM and/or flashing the EPROM, clear PCM DTCs and check the vehicle for proper operation. An improperly flashed EPROM may cause one or more of the following problems:

^ Poor engine performance
^ Surging
^ Loss of cruise control
^ Improper SERVICE ENGINE SOON Malfunction Indicator Lamp (MIL) operation
^ No starts
^ Hard starts
^ DTC P0602 sets
^ The vehicle will not start

Notice: In order to prevent internal PCM damage, leave the ignition OFF when installing or removing the PCM connectors and disconnecting or reconnecting the power to the PCM (battery cable, PCM pigtail, PCM fuse, jumper cables, etc.).

The EPROM and the EEPROM are soldered into the PCM and cannot be serviced separately.

EEPROM Data Following PCM Replacement

Since the data contained in the EEPROM is specific to the vehicle that the PCM is in, the EEPROM should reset if the PCM is installed in another vehicle.

When this reset occurs, the following data will be erased:

^ TP sensor learn
^ Transaxle adapts, including the following types:
^ Shifts
^ Steady state
^ Garage shifts
^ Transaxle oil life
^ Engine oil life
^ PCM odometer reading

Resetting the TP sensor learn will trigger DTC P1526. Resetting the transaxle oil life will trigger the Change Trans Fluid message. Resetting the engine oil life will trigger the Change Engine Oil Now message. The TP sensor learn can be relearned by following the DTC P1526 table. The transaxle oil life may be reset to its previous value using the PCM transaxle oil life override. The engine oil life may be reset to 100 by displaying the Oil life left and pressing the Reset button. The transaxle adapts will be relearned during normal operation. The PCMs learned odometer reading must be reset with a scan tool on vehicles without a smart (serial data equipped) instrument panel (IP). Smart IPs communicate their odometer value to the PCM.