Possible causes

– Battery defective
– Loose or missing alternator drive belt
– Faulty alternator
– Open or short system voltage circuit

Tech notes

Higher than expected voltage problems are most likely caused by bad voltage regulator. The voltage regulator is part of the alternator.

When is the code detected?

The Powertrain Control Module (PCM) has detected that the electrical system voltage level is too high.

Symptoms

– Engine Light ON (or Service Engine Soon Warning Light)

P0563 CHEVROLET Description

The Powertrain Control Module (PCM) continuously monitors the system voltage. The system voltage information is taken from the PCM’s ignition feed circuits. Voltages below 8.0 volts or above 17.1 volts causes improper system operation and/or component damage. If the system voltage is low the PCM raises the idle speed in order to increase the generator output. The PCM disables most outputs to protect the hardware if the system voltage is high. A scan tool may not display data if system voltage is outside this range.