GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Generic 🢒 2008 🢒 Unit Repair 🢒 DTC 🢒 DTC P0512, P0562, P0563, or P1682

Diagnostic Instructions
    • Perform the Powertrain On Board Diagnostic (OBD) System Check 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 P0512: Ignition 1 Switch Circuit 1

DTC P0562: System Voltage Low

DTC P0563: System Voltage High

DTC P1682: Ignition 1 Switch Circuit 2

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 ignition is ON, or the engine is running
    • The system voltage is between 10-18 volts

Conditions for Setting the DTC

DTC P0562

The ECM detects the system voltage is less than 10 volts.

DTC P0563

The ECM detects the system voltage is greater than 16 volts.

DTC P1682 and P0512

The ECM detects the ignition 1 voltage inputs from the Run/Crank relay is greater than 3 volts different than the ignition 1 voltage of the powertrain relay for greater than 2 seconds.

Action Taken When the DTC Sets
    • DTCs P0562 and P0563 are Type C DTCs.
    • DTCs P0512 and P1682 are Type B DTCs.

Conditions for Clearing the DTC
    • DTCs P0562 and P0563 are Type C DTCs.
    • DTCs P0512 and P1682 are Type B DTCs.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

    •  Engine Control Module Connector End Views
    •  Engine Controls Connector End Views

Electrical Information Reference

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

DTC Type Reference

Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Engine Control Module Scan Tool Information

Circuit/System Verification
  1. Ignition ON, test for 11-14 volts between the terminals of the battery.
    2. ⇒If not within the specified range, charge and test the battery, replace if necessary.
  2. Engine idling, the battery voltage tested in step 1 should increase.
    3. ⇒If the battery voltage does not increase, repair the charging system condition.
  3. Ignition ON, command the Powertrain relay ON and OFF with a scan tool. The relay should respond to the scan tool commands.
    4. ⇒If the relay does not respond to the scan tool commands refer to DTC P0685, P0689, or P0690 for further diagnosis.
  4. Observe the scan tool Battery Voltage parameter. Compare the scan tool voltage parameter to the battery voltage displayed on the DMM. The scan tool parameter and the DMM should display within 1 volt of each other.
  5. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Circuit/System Testing
  1. Ignition OFF. Disconnect the ECM harness connectors X2 and X3. Test for less than 1 ohm between the following ground circuit terminals and ground.
    2. • X2-73
    • X3-73
    ⇒If greater than the specified range, test the ground circuit for an open/high resistance.
  2. Load test for battery voltage between the following battery positive voltage circuit terminals and ground.
    3. • X1-10
    • X1-19
    • X1-20
    ⇒If not within the specified range, repair the battery positive voltage circuit for a short to ground or an open/high resistance.
  3. If all circuits test normal, replace the ECM.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Engine Control Module Replacement for ECM replacement, setup, and programming.