Circuit Description
The Crankshaft Position (CKP) sensor is supplied ignition voltage and a ground. The CKP sensor is mounted near the crankshaft and monitors a toothed crankshaft reluctor wheel. As the crankshaft spins the toothed reluctor wheel, a signal is induced into the CKP sensor. The gasoline control module (VCM/PCM or ECM) and the AF ECU use the CKP signal to determine engine speed, crankshaft position, and if a cylinder misfire is present.
This DTC is used to indicate no CKP reference signal is being monitored by the AF ECU while engine sensor conditions indicate the crankshaft is rotating.
Conditions for Running the DTC
| • | The engine is operating on alternative fuel for an initial failure. The AF ECU will run this DTC in gasoline mode after an initial alternative fuel mode failure. |
| • | No AF ECU 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 AF ECU monitors no CKP reference signal during the 1 second that mass air flow is more than 3 grams per second.
Action Taken When the DTC Sets
The AF ECU will switch-over to gasoline fuel operation. The AF ECU will not attempt alternative fuel operation until the next ignition key cycle.
| • | The AF ECU will illuminate the MIL and store the DTC as History during ONE drive trip in which the diagnostic runs and fails. |
| • | The AF ECU 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 AF ECU 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. |
| • | Interruption of Control Module (AF ECU / VCM / PCM or ECM) power or ground MAY clear DTC Information. Clearing DTC Information with this method is inconsistent and should not be performed. |
Diagnostic Aids
For this DTC, the AF ECU uses MAF sensor airflow values in order to determine when the engine is cranking or running. The VCM uses cam sensor pulses for the VCM DTC. An AF ECU DTC (but not a VCM DTC) would result during any condition (such as a disconnected MAF sensor) that causes airflow to be indicated with the ignition ON, and the engine OFF.
Fault Not Present
Fault Not Present indicates the condition that caused the DTC to set is intermittent and not currently present. Refer to Intermittent Conditions for additional information. If any additional DTCs were stored proceed to the applicable DTC table in the order stated in the OBD System Check.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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This step determines if the condition affects the gasoline control module.
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This step determines if the fault is present.
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This step determines if the CKP sensor is capable of creating a good 4X reference signal.
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This step determines if the AF ECU fault is present.
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This step determines if the CKP sensor signal circuit is good between the circuit splice and the AF ECU connector terminal.
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For this DTC, the AF ECU uses MAF sensor airflow values in order to determine when the engine is cranking or running. The VCM uses cam sensor pulses for the VCM DTC. An AF ECU DTC P0336 (but not a VCM DTC) would result during any condition that causes cranking or running engine airflow to be indicated by the MAF sensor with the ignition ON, and the engine OFF.
Step | Action | Value(s) | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the AF Powertrain On-Board Diagnostic (OBD) System Check? | -- | Go to Alternative Fuels (AF) Powertrain On Board (OBD) System Check | |||||||
Using the scan tool, establish communication with the gasoline control module (VCM/PCM or ECM), and review DTC information. Is this DTC also stored in the gasoline control module (VCM/PCM or ECM)? | -- | |||||||||
Crank and attempt to start the engine. Does the engine start and run? | -- | |||||||||
4 |
Does the test lamp illuminate? | -- | ||||||||
5 | Connect the test lamp between the CKP sensor ignition positive voltage circuit terminal and the CKP sensor Ground circuit terminal. Does the test lamp illuminate? | -- | ||||||||
Is the duty cycle within the specified range? | 23-43 % | |||||||||
7 |
Was a repair necessary? | -- | ||||||||
Does this DTC set? | -- | |||||||||
9 | The fault is not present. Refer to Diagnostic Aids. Are any DTCs stored that have not been diagnosed? | -- | Go to Intermittent Conditions | |||||||
Is the duty cycle more than the specified value? | 23 % | |||||||||
Was a repair necessary? | -- | |||||||||
12 | Repair the open 4X CKP sensor signal circuit between the circuit splice and the AF ECU connector terminal. Is the repair complete? | -- | -- | |||||||
13 | Repair the cause of no ignition voltage to the CKP sensor connector. Is the repair complete? | -- | -- | |||||||
14 | Repair the open CKP sensor ground circuit or faulty terminal contact at the gasoline control module connector. Is the repair complete? | -- | -- | |||||||
15 |
Important: In order to perform the variation learn procedure a switch-over to gasoline operation is necessary. Remove the CNG 20 amp fuse in order to perform the switch-over. Is the replacement complete? | -- | -- | |||||||
16 |
Is the replacement complete? | -- | -- | |||||||
17 |
Important: The following control module replacement procedures must all be completed before attempting to operate the vehicle.
Important: In order to perform the variation learn procedure, a switch-over to gasoline operation is necessary. Remove the CNG 20 amp fuse in order to perform the switch-over. All of the above procedures are located in the gasoline service manual. Is the replacement complete? | -- | -- | |||||||
18 |
Did this DTC RUN and PASS? | -- | System OK |
