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 P2510: Engine Control Module Relay Circuit

Diagnostic Fault Information

ECM Circuits

Short to Ground

Open

Short to Voltage

PWR/TRN Relay Control

P2510¹

²

²

ECM IGN 1 Voltage

²

²

P2510¹

PWR/TRN Battery Voltage - Switch

²

²

--

PWR/TRN Battery Voltage - Coil

²

²

--

¹ DTC will set only after the ECM powers down

² These circuit faults will cause a loss of communication with the scan tool and a no crank, no start condition.

Circuit/System Description

The ignition relay is normally an open relay. The relay armature is held in the open position by spring tension. When the ignition switch is turned to the Run or Start position, current will flow through the relay coil. A wire connected to the other end of the relay coil completes the path to ground through the engine control module (ECM). The electromagnetic field created by the relay coil overcomes the spring tension and moves the armature, allowing the contacts to close.

When the ignition switch is turned to the OFF position, the electromagnetic field collapses. This action allows the spring tension to move the armature away from the relay contacts, which interrupts current flow to the fuses.

If the relay fails to close, the engine will not crank. Communication will not be available with the use of a scan tool.

The relay table assumes that the vehicle battery is fully charged. Refer to Battery Inspection/Test.

Conditions for Running the DTC

    • The engine has transitioned from start to run.
        OR
    • After the ignition is turned OFF before ECM power down.

Conditions for Setting the DTC

    • Relay is responding incorrectly to the ECM command to de-energize.
    • This diagnostic test runs twice a drive cycle.

Action Taken When the DTC Sets

DTC P2510 is a Type A DTC.

Conditions for Clearing the DTC

DTC P2510 is a Type A DTC.

Reference Information

Schematic References

    •  Engine Controls Schematics
    •  Ground Distribution Schematics
    •  Power Distribution Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

    •  Battery Inspection/Test
    •  Circuit Testing
    •  Connector Repairs
    •  Probing Electrical Connectors
    •  Testing for Intermittent Conditions and Poor Connections
    •  Troubleshooting with a Test Lamp
    •  Wiring Repairs

Special Tools

J 43244 Relay Puller Pliers

Circuit/System Verification

  1. If any DTCs other than DTC P2510 are set, diagnose those DTCs first. Refer to Diagnostic Trouble Code (DTC) List - Vehicle.
  2. Important:  If you cannot duplicate the condition, operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle with the conditions that you observed from the Freeze Frame/Failure Records.

  3. The engine starts and runs.
  4. DTC 2510 is not set.
  5. Engine running, observe the DTC information with a scan tool. DTC P2510 should not set.
  6. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Circuit/System Testing

    Important: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.

  1. With the ignition ON, disconnect the PWR/TRN relay and observe with the scan tool for loss of communication.
  2. If the scan tool can still communicate with the vehicle, test the IGN 1 voltage circuit supplied by the ECM relay for a short to voltage. If the circuits test normal, replace the ECM.
  3. With the ignition OFF, probe the relay control circuit 19 X2 at the underhood electrical center with a test lamp connected to battery voltage.
  4. If the test lamp illuminates test the relay control circuit for a short to ground. If the circuits test normal, replace the ECM.
  5. With the ignition ON, probe the relay control circuit 19 X2 at the underhood electrical center with a test lamp connected to a good ground.
  6. If the test lamp illuminates, repair the short to voltage.
    If the test lamp does not illuminate, replace the relay.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Relay Replacement
    •  Control Module References for ECM replacement, setup, and programming