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 P0562: System Voltage Low

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Ignition 1 Signal

P0562

P0562

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Circuit/System Description

The engine control module (ECM) monitors the 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 above 8 km/h (5 mph).
    • The system voltage is between 9.5-18 volts.

Conditions for Setting the DTC

The ECM detects a system voltage below 10 volts for 5 seconds.

Action Taken When the DTC Sets

DTC P0562 is a C type DTC.

Conditions for Clearing the DTC

DTC P0562 is a C type DTC.

Reference Information

Schematic Reference

Engine Controls Schematics for the 7.8L engine.

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

Engine running, observe the scan tool ECM Ignition 1 Signal parameter. The Ignition 1 Signal parameter should read 10.5 volts or greater.

Circuit/System Testing

  1. Verify that DTC P0562 is set as current.
  2. If the DTC is history refer to Charging System Test
  3. Engine running, measure the voltage at the battery terminals and compare it with the Ignition 1 Signal parameter. The battery and Ignition 1 signal readings do not differ more than 2 volts.
  4. If greater than the specified value, test the Ignition 1 circuits and ground circuits for an open/high resistance.
    • Ignition 1 signal circuits 7.8L X1 terminals 22- 49- 50-73.
    • Ground circuits 7.8L X1 terminals 1-2-3-4.
  5. If the circuits test normal, replace the ECM.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

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