P0603
CIRCUIT DESCRIPTIONThe Engine Control Module (ECM) contains data that is essential to running the engine. The ECM continuously checks the integrity of this data.
CONDITIONS FOR RUNNING THE DTC
During the engine power down phase the ECM performs this test.
CONDITIONS FOR SETTING THE DTC
The ECM determines that an internal data test did not pass.
ACTION TAKEN WHEN THE DTC SETS
^ The control module illuminates the Malfunction Indicator Lamp (MIL) when the diagnostic runs and fails.
^ The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.
CONDITIONS FOR CLEARING THE MIL/DTC
^ The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
^ A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
^ A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
^ Use a scan tool in order to clear the MIL and the DTC.
DIAGNOSTIC AIDS
This Diagnostic Trouble Code (DTC) may set if the battery is disconnected while the ECM is powered-up. This DTC and several others may set if the switched B+ or the battery supply is removed from the ECM while the ECM is powered up. Test for intermittent or poor connections on the switched B+ and the battery supply circuits at the ECM. Also test the control circuit for the engine controls power relay for in intermittent open or high resistance and inspect the terminal contact at the relay. Refer to Testing for Intermittent and Poor Connections in Diagrams.
TEST
