P1650

DTC P1650

Circuit Description

The AF fuel pump relay disables the gasoline fuel pump when the engine is operating on CNG. The alternative fuels ECM turns the relay ON about 2 seconds after the engine is cranked or started on gasoline. The alternative fuels ECM monitors the voltage on the AF fuel pump relay control circuit. If the alternative fuels ECM detects an incorrect voltage on the AF fuel pump relay control circuit, DTC P1650 sets.


Conditions for Running the DTC

The ignition voltage is between 6-18 volts.


Conditions for Setting the DTC

* The alternative fuels ECM detects that the commanded state of the driver and the actual state of the control circuit do not match.
* All the above conditions are present for a minimum of 2 seconds.



Action Taken When the DTC Sets

* The alternative fuels ECM will not illuminate the MIL.
* The alternative fuels ECM will store this DTC as History during one drive trip in which the diagnostic runs and fails.
* The alternative fuels ECM will record operating conditions at the time the DTC sets. This information will be stored as Freeze Frame data.



Conditions for Clearing the DTC

* The Last Test Failed status will clear when the DTC runs and passes.
* The History status will clear after 40 consecutive warm-up cycles with no failures of any DTC.
* All DTC information can be cleared using a scan tool.



Test Description

The numbers below refer to the step numbers on the diagnostic table.
2. Listen for a click when the relay operates. Command both the ON and the OFF states. Repeat the commands as necessary.

4. This step verifies that the alternative fuels ECM is providing a ground to the AF fuel pump relay.
5. This step tests for an open in the power circuit to the AF fuel pump relay.