Powertrain Management (CNG)

DTC P1635

Circuit Description

Certain engine sensors require a 5 volt reference voltage source. The PCM supplies this voltage. The individual sensor 5 volt reference voltage circuits are shared within the PCM. The alternative fuels ECM monitors the 5 volt reference voltage the PCM supplies.


Conditions for Running the DTC

The ignition voltage is between 6-18 volts.


Conditions for Setting the DTC

* The alternative fuels ECM monitors a 5 volt reference voltage that is less than 4 volts or greater than 6 volts.
* The condition exists for at least 1 second.



Action Taken When the DTC Sets

* The alternative fuels ECM will 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 alternative fuels ECM will turn OFF the MIL after 3 consecutive drive trips that 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.