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 - ECM

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

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 if the voltage is out of range. If the ECM detects that the system voltage is too low, then DTC P0562 sets.

Conditions for Running the DTC

The engine is running.

Conditions for Setting the DTC

The ECM detects that the system voltage is less than 9 volts for 5 seconds.

Action Taken When the DTC Sets

DTC P0562 is a type C DTC.

Conditions for Clearing the DTC

DTC P0562 is a type C DTC.

Diagnostic Aids

A low voltage DTC in multiple modules indicates a concern in the charging system.

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

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Testing

  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 15.0 volts.
  2. If not within the specified range, refer to Charging System Test.
  3. Ignition OFF, disconnect the harness connectors at the ECM.
  4. Ignition OFF and scan tool disconnected, open and close the driver door, and wait 1 minute. Test for less than 5 ohms between the ground circuit terminal 73 X2 and ground.
  5. If greater than the specified range, test the ground circuit for an open/high resistance.
  6. Verify that a test lamp illuminates between the B+ circuit terminal 20 X1 and ground.
  7. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
  8. Install a 3A jumper wire between the PWR/TRN relay control circuit terminal 40 X1 and ground.
  9. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminals listed below and ground.
  10. • Terminal 18 X1
    • Terminal 19 X1
    • Terminal 13 X2
  11. If all 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.