P0340
DTC P0340 Camshaft Position (CMP) Sensor Circuit
Circuit Description
The camshaft position (CMP) sensor is a sensor designed to detect changes in a magnetic field. The control module (PCM/VCM) supplies the CMP sensor with signal and ground circuits. Ignition voltage is supplied to the CMP sensor by an independent circuit. The CMP sensor produces a magnetic field whenever the ignition is ON. The CMP sensor is mounted near a reluctor wheel that is attached to the distributor shaft. When the distributor shaft rotates (the engine is cranking or running) the reluctor wheel changes the magnetic field. The CMP sensor converts each change in the magnetic field into a PULSE. The number of teeth on the reluctor wheel determines how many pulses the CMP sensor detects per camshaft rotation. The control module uses the CMP sensor signal in order to calculate the correct timing for sequential fuel injection.
If the VCM does not detect the CMP signal while the engine is running this DTC will be set.
Conditions for Running the DTC
The engine is running.
Conditions for Setting the DTC
The CMP sensor reference pulse is not detected once every two crankshaft revolutions.
Action Taken When the DTC Sets
- The control module illuminates the malfunction indicator lamp (MIL) if a failure is detected during 2 consecutive key cycles.
- The control module sets the DTC and records the operating conditions at the time the diagnostic failed. The failure information is stored in the scan tool's Freeze Frame and Failure Records.
Conditions for Clearing the MIL/DTC
- The control module turns OFF the MIL after 3 consecutive drive trips when the test has Run and Passed
- A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles. A warm up cycle occurs when the coolant temperature has risen 22° C (4OC° F) from the startup coolant temperature and the engine coolant reaches a temperature that is more than 70° C (158° F) during the same ignition cycle.
- Use the scan tool Clear Information function
Diagnostic Aids
Electro-magnetic interference from the ignition coil or the spark plug wires could cause a poor signal condition in the CMP signal circuit to the VCM. Also check for the installation of aftermarket accessories and harnesses creating an electro-magnetic interference. Refer to Symptoms.
An intermittent may be caused by any of the following conditions:
- A poor connection
- Rubbed through wire insulation
- A broken wire inside the insulation
Thoroughly check any circuitry that is suspected of causing the intermittent complaint. Refer to Testing for Intermittent and Poor Connections.
If a repair is necessary, refer to Wiring Repairs or Connector Repairs.
Steps 1 - 2:
Steps 3 - 5:
Steps 6 - 12:
Steps 13 - 17:
Test Description
The numbers below refer to the step numbers in the diagnostic table.
2. This step determines if the DTC P0340 is the result of a hard failure or an intermittent condition.
5. This step will check for a signal output from the CMP sensor. The signal can also be read in AC voltage, approximately 5 - 7 volts AC.
8. If there are not any additional DTCs set, then refer to Diagnostic Aids for examples of conditions that could cause an intermittent loss of signal from the CMP sensor