P0603

Diagnostic Chart:

Wiring Diagram:

CIRCUIT DESCRIPTION

The VCM contains a memory area where it stores certain data it needs to save when the ignition is turned OFF. This area is called Keep Alive Memory. This diagnostic test monitors the VCMs keep alive memory for a loss or unintended change of data. If such a condition occurs, DTC P0603 sets.

CONDITIONS FOR SETTING THE DTC

If the checksum data of the Keep Alive Memory stored at power-down does not match the checksum data of the Keep Alive Memory at power-up, and the data read from memory does not match the data which is stored in the check memory function, DTC P0603 will set.

ACTION TAKEN WHEN THE DTC SETS

^ The VCM will illuminate the Malfunction Indicator Lamp (MIL) when the diagnostic runs and fails.

^ The VCM will record the operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and/or Failure Records.

CONDITIONS FOR CLEARING THE MIL/DTC

^ The VCM turns the MIL OFF after 3 consecutive drive trips when the test has Run and Passed and not Failed.

^ A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles (coolant temperature has risen 22°C (40°F) from the startup 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

It the battery has been disconnected for any reason DTC P0603 will set. The VCM checks the memory at powerup. If the memory changes, it will reset. An intermittent loss of power or ground to the VCM will also cause a reset.