Aurora V8-4.0L VIN C (1996)
Powertrain Control Module: Component Tests and General Diagnostics
EEPROM Diagnosis
PCM EPROM
The PCM contains an EPROM (Electrically Programmable Read Only Memory) that contains the calibration information used by the PCM to control
fueling, idle speed, ignition timing, transaxle shifts and emissions. This calibration information is based on various aspects of the vehicle such as
engine size, vehicle weight, transaxle type, final drive ratio, etc.
The EPROM is programmed (Flashed) with this critical information. Replacement PCM's used for service come without the programming, which must
be performed by the technician using the latest diagnostic tools and programs. Additionally, in certain situations, the diagnosis may require the
technician to reprogram (Flash) the PCM in an attempt to eliminate a DTC or condition. Therefore, it is crucial that the latest service publications
(bulletins, service manuals, etc.) be referenced for information concerning any new procedures or EPROM programs.
If the current program or an attempted reprogramming fails on the PCM, it will set DTC P0602.
PCM EEPROM
NOTE: Disconnecting the battery before the PCM is able to store the values may result in EEPROM reset, DTC P1526 and transaxle oil life and engine
oil life being reset to 0.
The PCM contains a data storage unit which can save critical data even when battery power is removed. This unit, the Electrically Erasable
Programmable Read Only Memory (EEPROM) is used by the PCM to store TP Sensor learned value, Transaxle Shift Adapt values, and Transaxle Oil
Life Index.
These values are stored in the EEPROM during the first 30 seconds after the key is turned OFF. Therefore, you should wait at least 30 seconds after
key OFF before disconnecting the battery to allow these values to be stored in the EEPROM.
The EEPROM is soldered into the PCM and cannot be serviced separately
POWERTRAIN CONTROL MODULE (PCM) AND FLASHING THE EPROM
NOTE: 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 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. Poor engine performance,
surging, loss of cruise control, improper SERVICE ENGINE SOON MIL operation, no starts, and/or hard starts may be caused by an improperly
flashed EPROM, in which case DTC P0602 may set and the vehicle may not start.
CAUTION: To prevent internal PCM damage, the ignition must be in the OFF (LOCK) position when disconnecting or reconnecting power to the
PCM, as when the battery cables, PCM connectors, or fuses are connected or disconnected.
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 (shifts, steady state, and garage shifts)
^
Transaxle oil life
^
Engine oil life
^
PCM odometer reading.
