P2146

DTC P2146

Circuit Description

The powertrain control module (PCM) grounds the AFO enable circuit when operating on CNG. When the AFO enable circuit is grounded the fuel injector control module (FICM) will operate the CNG injectors based upon the PCM pulse width signals. The PCM controls alternative fuel operation by grounding the AFO enable circuit via an internal switch called a driver. The primary function of the driver is to supply the ground for the controlled component. The PCM monitors the status of the driver. If the PCM detects an incorrect voltage for the commanded state of the driver, DTC P2146 sets.

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

- The PCM detects that the commanded state of the driver and the actual state of the control circuit do not match.
- The above condition exists for at least 1 seconds.

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.

Test Description

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

2. This step tests if the concern is active.
4. This step tests if a ground is constantly being applied to the AFO enable circuit. With the FICM disconnected, the PCM will command gasoline operation. The AFO enable circuit should not illuminate the test lamp.
5. This step verifies that the PCM is providing ground to the AFO enable circuit.