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 ignition voltage on the ignition feed circuit to terminal 39 at the ECM. A system voltage DTC will set whenever the voltage is below a calibrated value.

Conditions for Running the DTC

Engine running time is greater than 120 seconds.

Conditions for Setting the DTC

System voltage is between 2.48-10.01 volts.

Action Taken When the DTC Sets

    • The malfunction indicator lamp MIL will be illuminated after 3 valid driving cycles.
    • The ECM will record operating conditions at the time of the diagnostic failure. This information will be stored in the Freeze Frame and Failure Records buffers.
    • A history DTC is stored.

Conditions for Clearing The MIL/DTC

    • The MIL will turn OFF after 3 or 4 consecutive driving cycles in which the diagnostic runs without a fault.
    • A history DTC will clear after 40 consecutive warm up cycles without a fault.
    • DTCs can be cleared by using the scan tool.
    • Disconnecting the ECM battery feed for 10 seconds

Circuit/System Verification

With the scan tool installed, ignition ON and the engine OFF, observe the Ignition 1 Signal parameter in the ECM data list. The Ignition 1 Signal parameter should read 10.5 volts or greater.

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 1 volt.
  2. If greater than 1 volt test the ignition 1, ground circuits of the ECM for 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