P0563 Battery/System voltage high

P0563 Code - this diagnostic runs when the following conditions are met, with the engine running and no other charging system DTCs set. Set condition, the Powertrain Control Module (PCM) detects that the Battery voltage is greater than the targeted charging system voltage by at least 1.0 volt for a calibrated period of time. MIL light illuminate.


P0563

Possible causes P0563 Code

  • Alternator field control circuit shorted to voltage
  • Alterntor sense circuit shorted to ground
  • Alternator sense circuit open/high resistance
  • Alternator
  • Powertrain Control Module (PCM)

Diagnose P0563 Code


Step 1. Check for an active condition
Inspect and and test the Battery with the Midtronics Battery tester or equivalent for a shorted or dead cell before continuing with this test.
Start the engine. With the scan tool, read the target charging voltage. Measure the voltage on the Alternator ouput stud.

Is the voltage more than 1.0 volt above the target charging voltage?

Yes, go to step 2.
No, perform the PCM intermittent condition.

Step 2. Check the Alternator duty cycle
With the scan tool, check the duty cycle reading for the Alternator. During normal operation the typical duty cycle of the field control at idle with minimal loads is approximately 35-40%, which will equate to between 4.0 and 5.0 volts. Depending on the charging issue, the PCM can drive the duty cycle to off (0%), which will equate to zero volts, or full field (100%), which will equate to between 11.0 and 12.0 volts.

What is the Alternator duty cycle on the scan tool?

0%, go to step 3.
100%, go to step 4.

Step 3. Check the Alternator field control circuit for a short to voltage
Back probe the Alternator field control circuit at the Alternator harness connector. Measure the voltage on the Alternator field control circuit at the Alternator harness connector.

Is there any voltage present?

Yes, repair the Alternator field control circuit for a short to voltage.
No, verify that there is good pin to terminal contact in the Alternator and Powertrain Control Module connectors. If no problem is found, replace the Alternator.

Step 4. Check the Alternator sense circuit for a short to ground
Turn the ignition off, disconnect the Alternator harness connector. Disconnect the PCM harness connector, check for continuity between ground and the Alternator sense circuit at the Alternator harness connector.

Is there continuity between ground and the Alternator sense circuit?

Yes, repair the Alternator sense circuit for ahort to ground.
No, go step 5.

Step 5. Check the Alternator sense circuit for an open/high resistance
Do not probe the PCM harness connectors. Probing the PCM harness connector will damage the PCM terminals resulting in poor terminal to pin connection. Measure the resistance of the Alternator sense circuit between the Alternator harness connector and PCM harness connector.

Is the resistance below 3.0 Ohms?

Yes, go to step 6.
No, repair the Alternator sense circuit for an open or high resistance.

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