P0563

Circuit Description
The PCM continuously monitors the system voltage. The system voltage information is taken from the PCM's ignition feed circuit. When the PCM detects a high or low voltage condition, the PCM operates in a default mode. If the system voltage is low, the PCM raises the idle speed in order to increase the generator output. If the system voltage is high, the PCM disables most outputs in order to protect the hardware. The Class 2 Serial Data circuit is shut down when system voltage is below 9.2 volts or above 16 volts. A scan tool may not display data if system voltage is outside of this range. Because of this, monitor the system voltage when diagnosing a current condition using a DMM J39200.

Conditions for Running the DTC
^ The engine operates longer than 10 seconds.
^ The engine speed is greater than 1000 RPM.
^ The vehicle speed is greater than 8 km/h (5 mph).

Conditions for Setting the DTC
The PCM senses system voltage above 18.0 volts for 5 seconds.

Action Taken When the DTC Sets
^ The PCM stores DTC P0563 in the PCM memory when the diagnostic runs and fails.
^ The Malfunction Indicator Lamp (MIL) will not illuminate.
^ The PCM will record the operating conditions at the time during which the diagnostic fails. The PCM stores this information in the Failure Records.
^ The PCM disables most outputs.
^ The transmission defaults to third gear.
^ The TCC operation is inhibited.
^ During the time the fault is present, the PCM will cycle the fans ON and OFF every few seconds.

Conditions for Clearing the MIL/DTC
^ A History DTC will clear after forty consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
^ A last test failed (Current DTC) will clear when the diagnostic runs and does not fail.
^ Use a scan tool in order to clear the MIL/DTC.

Diagnostic Aids

Important:
^ Remove any debris from the PCM/TAC module connector surfaces before servicing the PCM/TAC module. Inspect the PCM/TAC module connector gaskets when diagnosing/replacing the modules. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion into the PCM/TAC modules.
^ For any test that requires probing the PCM or a component harness connector, use the Connector Test Adapter Kit J 35616-A. Using this kit prevents damage to the harness/component terminals.
^ The following may cause an intermittent:
- Poor connections.
- Mis-routed harness.
- Rubbed through wire insulation.
- Broken wire inside the insulation.
^ Test the generator voltage sense circuit for high resistance or loose connections. These could cause an intermittent overcharging condition.
^ Using Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame and/or Failure Records data can aid in determining how many miles since the DTC set. The Fail Counter and Pass Counter can also aid determining how many ignition cycles the diagnostic reported a pass and/or a fail. Operate the vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature etc.) that you observed. This isolates when the DTC failed.
^ For an intermittent, refer to Symptoms. Symptom Related Diagnostic Procedures

Test Description
The numbers below refer to the step numbers on the diagnostic table.
2. This step tests for excessive generator output. The voltage should remain below 17.1 volts.