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 P0560: System Voltage

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 below 40 km/h (25 mph).
    • The system voltage is below 11 volts or above 16 volts.
    • Engine speed is above 1,500 RPM.

Conditions for Setting the DTC

The ECM detects a system voltage out of range for 2 seconds.

Action Taken When the DTC Sets

    • The ECM will command the charge indicator and or warning message to be illuminated on the instrument panel cluster (IPC) and the driver information center (DIC), if equipped.
    • 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 message OFF after one trip in which the diagnostic test has been run and passed.
    • The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.

Reference Information

Schematic Reference

Starting and Charging Schematics

Connector End View Reference

Engine Electrical Connector End Views

Electrical Information Reference

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

Scan Tool Reference

    •  Scan Tool Data List
    •  Scan Tool Data Definitions

Circuit/System Verification

With the scan tool installed, engine running, observe the Ignition 1 signal parameter in the ECM data list. The ignition 1 signal parameter should read between 11.5-15.5 volts.

Circuit/System Testing

  1. Measure the voltage at the battery terminals and compare it with the Ignition 1 signal parameter in the ECM data list. Verify that battery and Ignition 1 signal readings do not differ more than 0.8 volt.
  2. If more than 0.8 volt, test the Ignition 1 and ground circuits of the ECM for an open, high resistance or replace the ECM.
  3. Refer to Charging System Test .

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for ECM replacement, setup, and programming