P0563

Electrical Diagram:

CIRCUIT DESCRIPTION

The PCM continuously monitors the system voltage. The system voltage information is taken from the PCMs ignition feed circuits. Since voltages below 8.0 volts or above 17.1 volts, could cause improper system operation and/or component damage, the PCM operates in a default mode if a PCM voltage DTC sets. 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 to protect the hardware. Class 2 Serial Data is shut down when system voltage is below 9.2 volts or above 16.0 volts. A scan tool will not display data if system voltage is outside this range. Because of this, use a DMM in order to monitor system voltage when checking to see if the fault is currently present.

CONDITIONS FOR SETTING THE DTC

^ Engine operates longer than 10 seconds.

^ The PCM senses system voltage above 17.1 volts for 5 seconds.

^ The condition is present.

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 the diagnostic fails. The PCM stores this information in Failure Records.

^ The PCM disables most outputs.

^ The transmission defaults to third gear.

^ Torque Converter Clutch (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.

^ The PCM battery voltage is interrupted.

^ Use a scan tool in order to clear the MIL/DTC.


DIAGNOSTIC AIDS

^ Check the generator voltage sense circuit for high resistance or loose connections. These could cause an intermittent overcharging condition. Refer to Charging/Starting for circuit details.

^ 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 will isolate when the DTC failed.

For an intermittent, refer to Symptoms. Testing and Inspection


TEST DESCRIPTION

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

2. This step checks for excessive generator output. The voltage should remain below 17.1 volts.