Powertrain Diagnosis

Wiring Diagram:

P0563 - SYSTEM VOLTAGE HIGH
The ECM monitors vehicle system voltage by monitoring the voltage on circuit 2740 coming from the main relay, which is referenced to the ECM case ground. Each of the three main relay pins going into the ECM are tied together internally in the ECM. When ignition voltage is present at the ignition 1 input to the FC?M (circuit 339), the ECM will command the main relay On by supplying ground to the main relay coil circuit. When the relay is energized, battery voltage should be present on each circuit 2740 at the ECM. DTC P0563 will set if the ECM detects higher than normal system voltage on circuit 2740 for a certain length of time after the engine has been running when the main relay has been commanded On.

DTC PARAMETERS
DTC P0563 will set it system voltage measured at the ECM main relay voltage circuit 2740 is greater than 16.0 volts when:
^ Conditions exists for longer than 0.2 seconds
^ Main relay is commanded On because the ECM detected ignition voltage present at the ignition 1 input to the ECM
^ Engine run time is greater than 3 minutes
^ Vehicle speed is present

DTC P0563 diagnostic runs continuously once the above conditions have been met.

P0563 is a type D DTC

DIAGNOSTIC AIDS
DTC P0563 indicates that the battery voltage supplied through the main relay to circuit 2740 was higher than normal, which most likely indicates a charging system problem.

To locate an intermittent problem. use Scan tool to monitor BATTERY voltage with engine running at 1300 rpm. With all accessories On or all accessories Off charging voltage should be in the range of 12.5-15.5 volts.

Perform a charging system test. Refer to "Starting and Charging".