P1621

Diagnostic Chart:

Wiring Diagram:

CIRCUIT DESCRIPTION

The Vehicle Control Module (VCM) Electrically Erasable Programable Read Only Memory (EEPROM) contains data which is essential to running the engine and transmission. The VCM program stores this data in the EEPROM. This data is remains in the EEPROM even if the battery is disconnected. At Powerup, the VCM checks the integrity of this data. If the checksum of the EEPROM does not match a predetermined value, DTC P1621 sets.


CONDITIONS FOR SETTING THE DTC

The VCM is unable to correctly read data from the EEPROM memory.


ACTION TAKEN WHEN THE DTC SETS

The VCM records the operating conditions at the time the diagnostic tails. The VCM stores this information in the scan tools Freeze Frame and/or the Failure Records.


CONDITIONS FOR CLEARING THE MIL/DTC

^ A history DTC will clear it no fault conditions have been detected for 40 warm-up cycles (coolant temperature has risen 22°C (40°F) from the start-up coolant temperature and the engine coolant temperature exceeds 70°C (160°F) during the same ignition cycle.

^ Use the scan tool Clear Information function.

^ Disconnect the VCM battery feed for 30 seconds.


DIAGNOSTIC AIDS

Replace the VCM even if this DTC exists only in history.


TEST DESCRIPTION

The numbers below refer to the step numbers on the diagnostic table.

2. Replace the VCM even it this DTC exists only in history.