GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

    •  Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    •  Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC P0563: System Voltage High - ECM 12V

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

12V  B+

P0562

P0562

P0563

--

Ground

--

P0562

P0563

--

Typical Scan Tool Data

Ignition 1 Signal - ECM

Circuit

Short to Ground

Open

Short to Voltage

Operating Conditions: Ignition ON, engine OFF.

Parameter Normal Value: 12.6 V

Ignition

0.0 V

0.0 V

12.6 V

Circuit/System Description

The engine control module (ECM) monitors the 12V system voltage to ensure that the voltage stays within the proper range. Damage to components, and incorrect data may occur when the voltage is out of range.

Conditions for Running the DTC

    • The vehicle speed is greater than 8 km/h (5 mph).
    • The 12V system voltage is between 9.5-18 V.

Conditions for Setting the DTC

The ECM detects a 12V system voltage above 16 V.

Action Taken When the DTC Sets

    • The ECM will command the charge indicator to be illuminated on the instrument panel cluster (IPC).
    • The ECM will not illuminate the malfunction indicator lamp (MIL).
    • The ECM will store conditions, which were present when the DTC set as Fail Records data only.

Conditions for Clearing the DTC

    • The ECM will command the indicator OFF after one trip in which the diagnostic test has been run and passed.
    • A history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.

Diagnostic Aids

    • This DTC could be set by overcharging with a battery charger.
    • A high voltage DTC in multiple modules indicates a concern in the charging system.

Reference Information

Schematic Reference

    •  Engine Controls Schematics
    •  Starting and Charging Schematics
    •  Power Distribution Schematics
    •  Ground Distribution Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Charging System Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

  1. Engine running, accessories OFF, measure and record the battery voltage at the 12V battery terminals. The voltage should be between 12.6 and 15.0 V.
  2. If not within the specified range, refer to Charging System Test.
  3. Observe the scan tool ECM Ignition 1 Signal parameter. The reading should be between 12.6 and 15.0 V.
  4. If greater than the specified range, replace the ECM.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for ECM replacement, setup, and programming.