P0342
DTC P0342 Camshaft Position (CMP) Sensor Circuit Low Voltage
Circuit Description
The camshaft position sensor is mounted through the top of the engine block at the rear of the engine. camshaft position sensor (CKP), is splined by a helical gear to the camshaft and rotates providing a 1X signal (one pulse per camshaft revolution). The powertrain control module (PCM) provides a 12 volt power supply to the CMP sensor as well as a ground and a signal circuit.
The camshaft position sensor is used to determine whether a cylinder is on a firing or exhaust stroke. As the camshaft rotates, the reluctor wheel interrupts a magnetic field produced by a magnet within the sensor. The sensors internal circuitry detects this and produces a signal which is read by the PCM. The PCM uses this 1X signal in combination with the crankshaft position sensor 24X signal to determine crankshaft position and stroke. This diagnostic for the camshaft position sensor checks for a loss of Camshaft Position sensor signal.
Note that as long as the 24X signal is available, the engine can start even if there is no camshaft position sensor signal. The PCM can determine when a particular cylinder is on either a firing or exhaust stroke by the 24X signal alone, but requires the cam signal to determine which (firing or exhaust). The system will attempt synchronization and look for an increase in MAF signal indicating the engine started. If no MAF increase is detected, the PCM assumes it incorrectly synchronized to the exhaust stroke and will re-sync to the opposite cam position. A slightly longer cranking time may be a symptom of this condition.
Conditions for Running the DTC
* System voltage is between 9.0 volts and 17.0 volts.
* Engine speed is less than 4000 RPM.
Conditions for Setting the DTC
The PCM detects the Cam signal is stuck low when the signal should be high for 1.5 seconds.
Action Taken When the DTC Sets
* The PCM will illuminate the malfunction indicator lamp (MIL) on the second consecutive drive trip that the diagnostic runs and fails.
* The PCM will record operating conditions at the time the diagnostic fails. The first time the diagnostic fails, this information will be stored in Failure Records. If the diagnostic reports a failure on the second consecutive drive trip, the operating conditions at the time of failure will be written to Freeze Frame and the Failure record will be updated.
Conditions for Clearing the MIL/DTC
* The PCM will turn the MIL OFF after 3 consecutive drive trips that the diagnostic runs and does not fail.
* A last test failed (Current DTC) will clear when the diagnostic runs and does not fail.
* A History DTC will clear after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
* PCM battery voltage is interrupted.
* Using a Scan tool
Diagnostic Aids
* The following mechanical problems may cause this DTC to set:
- Poor connections -Terminal tension at the sensor
- Camshaft reluctor wheel damage
- The sensor coming in contact with the reluctor wheel
- An improperly installed camshaft position sensor
* Using Freeze Frame and Failure Records data may aid in locating an intermittent condition. If the DTC cannot be duplicated, the information included in the Freeze Frame and Failure Records data can be useful in determining how many miles since the DTC set. The Fail Counter and Pass Counter can also be used to determine how many ignition cycles the diagnostic reported a pass and a fail. Operate vehicle within the same Freeze Frame conditions (RPM, load, vehicle speed, temperature etc.) that were noted. This will isolate when the DTC failed.
* For intermittent conditions, refer to Symptoms Symptoms.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
2. This step verifies that the fault is present. A hard start is observed when a malfunction is present.
4. This step checks the camshaft position sensor B+ reference circuit from the PCM to the CMP.
5. This step checks the camshaft position sensor ground circuit from the PCM to the CMP.
6. This step checks the camshaft position sensor signal circuit. Applying a voltage causes the CAM signal input - High to Low and Low to High parameter to increase if the circuit and the PCM are operating properly.
7. This step checks the Camshaft Position sensor output. The sensor must have a voltage supply and a ground to perform this test. A duty cycle that is present, indicates the condition is intermittent. Inspect the harness connectors for poor connections.
8. This step checks the camshaft position sensor B+ reference circuit from the PCM to the CMP sensor.
10. This step checks the camshaft position sensor ground circuit from the PCM to the CMP sensor.
