P1235

DTC P1223, P1226, P1229, P1232, P1235, P1238, P1241, or P1244

Circuit Description

The engine control module (ECM) enables the appropriate fuel injector on the compression stroke for each cylinder. The ECM controls the fuel injection control module (FICM) by grounding the control circuit via a solid state device called a driver. The ECM monitors the state of the driver. If the ECM detects an incorrect voltage for the commanded state of an injector driver, DTCs P1223, P1226, P1229, P1232, P1235, P1238, P1241, or P1244 will set.

Conditions for Running the DTC

- The engine is running.
- The ignition voltage is between 6-18 volts.

Conditions for Setting the DTC

- The ECM detects that the command state and the actual state of the control circuit does not match.
- The condition exists for less than one second.

Action Taken When the DTC Sets

- The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
- The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

Conditions for Clearing the MIL/DTC

- The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
- A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
- A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
- Clear the MIL and the DTC with a scan tool.

Diagnostic Aids






Refer to the following table to determine which fuel injector control circuit is malfunctioning.

Test Description














The numbers below refer to the step numbers on the diagnostic table.

4. This step determines how many fuel injector control circuit DTCs are set. If there is only 1 fuel injector DTC set, an open circuit, or poor connection is likely the cause of the concern. Refer to Diagnostic Aids in order to determine which cylinder is causing the condition.
5. This step determines if there are 4 or more fuel injector control circuit DTCs are set. A short to ground will set 4 fuel injector control circuit DTCs for cylinders 2, 3, 5, 8, or cylinders 1, 4, 6, 7. Refer to Diagnostic Aids in order to determine which cylinders are affected. If there are more than 4 fuel injector control circuit DTCs set, a short to voltage on a fuel injector control circuit is likely the cause of the concern. A short to voltage will set more than 4 fuel injector control circuit DTCs.
6. Jumpering this control circuit to ground energizes the relay supplying power to the FICM, allowing the FICM to power up without ECM control. This step verifies the FICM is supplying the appropriate voltage through the fuel injector control circuits to the ECM. If the DMM displays 5 volts, inspect for a poor connection at the ECM.
8. This step is testing for a short to ground on a fuel injector control circuit. If the test lamp illuminates on any fuel injector control circuit, a short to ground is the cause of the condition.
9. This step is testing for a short to a voltage. If the DMM displays a voltage greater than the specified value, a short to voltage is the cause of the condition.