Powertrain Management (CNG)

DTC P0341

Circuit Description

The camshaft position (CMP) sensor is a sensor designed to detect changes in a magnetic field. The powertrain control module (PCM) supplies the CMP sensor with a 12-volt reference, a low reference, and a signal circuit. The CMP sensor produces a magnetic field whenever the ignition is ON. The CMP sensor is mounted near a reluctor wheel that is part of the camshaft. When the camshaft rotates the reluctor wheel interrupts the magnetic field. The CMP sensor converts each change in the magnetic field into a pulse. The PCM and the alternative fuels ECM use the CMP sensor signal in order to calculate the correct timing for sequential fuel injection. If the alternative fuels ECM does not detect the CMP signal while the engine is running, this diagnostic trouble code (DTC) will set.


Conditions for Running the DTC

* DTCs P0101, P0102, P0103 are not set.
* MAP value is less than 105 kPa.
* The MAF is greater than 3 gms/sec.



Conditions for Setting the DTC

* The alternative fuels ECM does not detect a CMP sensor reference pulse.
* The condition exists for at least 2 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 determines if the fault is present.
4. This step determines if the condition affects the PCM. If the CMP high to low and low to high transition parameters increment, then the condition only affects the alternative fuels ECM.
5. This step tests the ignition feed circuit of the CMP sensor.
6. This step tests the low reference circuit of the CMP sensor.
7. This step tests the signal circuit of the CMP sensor. If the scan tool parameters increment when the test lamp contacts the signal circuit, then the wiring and modules are OK.
8. This step tests if the alternative fuels ECM is the cause of the condition. If the scan tool parameters increment when the alternative fuels ECM is disconnected, the signal circuit, and the PCM are OK.