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 P0687: Engine Controls Ignition Relay Control Circuit High VoltageCircuit/System Description
The engine control module (ECM) main relay is energized when the ECM receives an ignition switch ON signal.
Conditions for Running the DTC
| • | The ignition switch is OFF. |
| • | The engine is OFF. |
Conditions for Setting the DTC
The ECM detects that the ECM main relay has been ON, high voltage, after the ignition switch was turned OFF.
Action Taken When the DTC Sets
DTC P0687 is a Type D DTC.
Conditions for Clearing the DTC
DTC P0687 is a Type D DTC.
Diagnostic Aids
Inspect for any recent engine mechanical repairs. An incorrectly installed ECM main relay will cause this DTC to set.
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
Verify the integrity of the ECM Main Relay by inspecting for the following conditions:
| • | Damaged components |
| • | Loose or improper installation |
Circuit/System Testing
Important: You must perform Circuit/System Verification before proceeding with Circuit/System Testing.
- Ignition OFF and the ECM main relay harness disconnected, measure for 0 volts on the ECM main relay circuits.
- Ignition OFF and the ECM main relay harness disconnected, probe the ECM main relay circuits with a test lamp connected to battery voltage. Verify the test lamp does illuminate on either circuit.
| ⇒ | If the voltage is more than 0 volts, test the affected motor control circuit for a short to voltage. |
| ⇒ | If the circuits test normal, replace the ECM main relay. |
| ⇒ | If the test lamp does not illuminate, test the affected motor control circuit for a short to ground. If the circuits test normal, replace the ECM. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Relay Replacement |
| • | Control Module References for engine control module (ECM) replacement, setup, and programming |
