P1264

DTC P1264

Circuit Description
The common 1 injector drive circuit is a high-voltage supply (near 120 volts) which drives injectors for cylinder 1 and 4 in conjunction with the engine control module (ECM) grounding the injector control circuit. The ECM supplies battery voltage on the injector drive circuit to allow for fault detection. If the common 1 injector drive circuit supply to the cylinder 1 and 4 is shorted to a voltage circuit, this DTC will set. Or, if the injector solenoid control circuit 1 or 4 is shorted to voltage, this DTC will also set.

Condition for Running the DTC
- The battery voltage is between 10-16 volts.
- The ignition switch is ON.
- The engine is running.

Condition for Setting the DTC
- The ECM detects that the common 1 fuel injector power supply circuit or cylinder 1 or 4 fuel injector solenoid control circuit is shorted to voltage.

Action Taken When the DTC Sets
- The ECM illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
- The ECM records the operating conditions at the time the diagnostic fails. The ECM stores this information in the Failure Records.
- The ECM disables cylinder 1 and 4 injector operation.
- The ECM limits fuel injection quantity within 50%.
- The ECM limits fuel rail pressure within 11600 psi (80 MPa).
- The ECM closes the EGR valve and holds to close position.
- The ECM inhibits the cruise control.

Condition for Clearing the DTC
- A current DTC clears when the ignition is turned OFF.
- Clear the MIL and the DTC with a scan tool.

Diagnostic Aids
If an intermittent condition is suspected, the following may cause an intermittent:
- Misrouted harness.
- Rubbed through wire insulation.

Check for the following conditions:
- Damaged harness: Inspect the wiring harness for damage. If the harness appears to be OK, observe the "DTC P1264" display on the scan tool with engine running while moving connectors and wiring harness. A change in the display will indicate the location of the fault.

DTC P1264

Schematic Reference: Engine Controls Schematics

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