GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Holden 🢒 2009 🢒 Epica 🢒 DTC 🢒 DTC P068A, P068B, or P2510

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 Descriptors

DTC P068A: Engine Controls Ignition Relay Control Circuit

DTC P068B: Engine Controls Ignition Relay Control Circuit

DTC P2510 58: Engine Controls Ignition Relay Control Circuit Incorrect Reaction After Event

DTC P2510 59: Engine Controls Ignition Relay Control Circuit/Component Protection Time-Out

Circuit/System Description

The Engine Controls Ignition Relay or Main Relay, is controlled by the engine control module (ECM) depending upon input from the ignition switch. Battery positive voltage is supplied to the relay coil and switch. When the ignition switch is turned to the ON position, the ECM will provide ground on the control circuit of the relay using a low side driver. This will allow voltage through the relay switch contacts to the components. The ECM monitors the voltage level on the control circuit of the relay.

Conditions for Running the DTC

P068A and P2510 58

    • The ignition is ON, or the engine is running.
    • The DTCs run continuously once the above condition is met.

P068B and P2510 59

    • The ignition is switched OFF.
    • The DTC runs continuously until the ECM powers down.

Conditions for Setting the DTC

The ECM detects the Engine Controls Ignition Relay Control Circuit is open, shorted to ground, or shorted to voltage.

Action Taken When the DTC Sets

DTCs P068A, P068B, and P2510 are Type C DTCs.

Conditions for Clearing the DTC

DTCs P068A, P068B, and P2510 are Type C DTCs.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

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

Important: If you were sent here from Engine Cranks But Does Not Run proceed to Circuit/System Testing.

  1. Ignition ON, observe the DTC information with a scan tool. DTCs P068A, P068B, or P2510 should not set.
  2. Cycle the ignition from OFF to ON. You should hear and feel an audible click from the main ignition relay. Repeat as necessary in order to verify main ignition relay operation.
  3. 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 main ignition relay.
  2. Ignition ON, verify that a test lamp illuminates between the relay coil ignition 1 voltage circuit terminal 85 and ground.
    3. ⇒If the test lamp does not illuminate, repair the relay coil ignition 1 voltage circuit for a short to ground or an open/high resistance.
  3. Ignition OFF, connect a test lamp between the relay coil control circuit terminal 86 and the relay coil ignition 1 voltage circuit terminal 85. The test lamp should not be illuminated.
    4. ⇒If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the ECM.
  4. Ignition ON. The test lamp should turn ON.
    5. ⇒If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If circuit tests normal, replace the ECM.
  5. Connect a 20A fused jumper wire between the relay switch B+ circuit terminal 30 and the relay switch ignition 1 voltage circuit terminal 87.
  6. Attempt to start the engine. The engine should start.
    7. ⇒If the engine does not start, test the ignition 1 voltage circuit between the EC ignition relay and the ECM for a short to ground or for an open/high resistance. If the circuit tests normal, replace the ECM.
  7. If all circuits test normal, test or replace the main ignition relay.

Component Testing
  1. Ignition OFF, disconnect the main ignition relay.
  2. Test for 70-110 ohms between terminals 85 and 86.
    3. ⇒If not within the specified range, replace the relay.
  3. Test for infinite resistance between the following terminals:
    4. • 30 and 86
    • 30 and 87
    • 30 and 85
    • 85 and 87
    ⇒If not the specified value, replace the relay.
  4. Install a 10A fused jumper wire between relay terminal 85 and 12 volts. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 ohms between terminals 30 and 87.
    5. ⇒If greater than the specified range, replace the relay.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for ECM replacement, setup, and programming