Powertrain Management (CNG)

DTC P0336

Circuit Description

The powertrain control module (PCM) monitors the crankshaft position sensor (CKP) signal in order to determine engine speed. The PCM signals engine speed to the Alternative Fuels ECM by pulse-width-modulating the engine speed signal circuit.


This DTC indicates no engine speed signal is being monitored by the Alternative Fuels ECM while the MAF sensor signal indicates the crankshaft is rotating.


Conditions for Running the DTC

* No Alternative Fuels ECM MAF sensor DTCs are set this ignition cycle.
* The MAP sensor signal indicates 105.23 kPa (31.07 in Hg) or less.
* The mass air flow is more than 3 grams per second for 1 second continuously.



Conditions for Setting the DTC

The Alternative Fuels ECM does not monitor an engine speed signal during the 1 second that mass air flow is more than 3 grams per second.


Action Taken When the DTC Sets

* The Alternative Fuels ECM will switchover to gasoline operation on KL6 equipped vehicles.
* The Alternative Fuels ECM will illuminate the MIL and store the DTC as History during 1 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 MIL/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 with a scan tool.



Test Description

The numbers below refer to the step numbers on the diagnostic table.
2. This step determines if the condition is causing a no start.
3. This step determines if the condition affects the PCM.
4. This step determines if the fault is present.