P0340

DTC P0340 CMP Sensor Circuit




Circuit Description
The Camshaft Position sensor is a three wire Hall effect sensor is used to determine when cylinder #1 is on its compression stroke. The CMP sensor has an ignition feed circuit, a ground circuit and a signal circuit. The signal is detected at the VCM on the signal circuit. This signal is used by the VCM to coordinate fuel control, ignition controlled spark timing and for use in some engine diagnostics.

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 crankshaft revolution.

Action Taken When the DTC Sets
The VCM illuminates the MIL after 2 consecutive driving cycles with the fault active.

Conditions for Clearing the MIL/DTC
- The VCM 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 (coolant temperature has risen 22 °C (40 °F) from the startup coolant temperature and the engine coolant temperature is more than 70 °C (158 °F) during the same ignition cycle)
- Use the scan tool Clear Information function.

Diagnostic Aids
Refer to Symptoms.

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. Ensure the routing of the CMP sensor circuitry is correct.

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 Intermittents and Poor Connections Diagnosis.

If a repair is necessary, then refer to Wiring Repairs or Connector Repairs.

Steps 1 - 4:

Steps 5 - 10:

Steps 11 - 15:

Steps 16 - 17:

Test Description
The number(s) below refer(s) to the step number(s) 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.
8. If there is not any additional DTCs set, refer to Diagnostic Aids for examples of conditions that could cause an intermittent loss of signal from the camshaft position (CMP) sensor.
9. Checking for a short to ground in this circuit may prevent the circuit from opening again.