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

IGN / B+

P0562

P0562

--

--

Ground

--

P0562

--

--

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 V.

Conditions for Setting the DTC

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

Action Taken When the DTC Sets

    • The instrument panel cluster (IPC) illuminates the charge indicator.
    • The driver information center (DIC) displays the CHARGING SYSTEM / GENERATOR FAULT warning message.

Conditions for Clearing the DTC

DTC P0562 is a C type DTC.

Diagnostic Aids

    • A low voltage DTC in multiple modules indicates a concern in the charging system.
    • Inspect the ECM ground connections, to verify that they are clean and tight.

Reference Information

Schematic Reference

Engine Controls 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

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

  1. Engine running, accessories OFF, measure and record the voltage at the battery voltage at the battery terminals. The voltage should be between 12.6 and 15.5 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 15.5 V.

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connectors at the ECM.
  2. Ignition OFF and scan tool disconnected, open and close the driver door, and wait 1 minute. Test for less than 5 Ω between the ground circuit terminal 73 X2.
  3. If greater than the specified value, test the ground circuits for an open/high resistance.
  4. Ignition ON, verify a test lamp illuminates between the IGN / B+ circuits terminals listed below and ground.
  5. • IGN terminal 18 X1
    • IGN terminal 19 X1
    • IGN terminal 13 X2
    • B+ terminal 20 X1
    If the test lamp does not illuminate , test the IGN / B+ circuits for an open/high resistance.
  6. 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.