P0340

CIRCUIT DESCRIPTION
The DTC P0340 Camshaft Position (CMP) Sensor Circuit diagnostic monitors the output of the CMP sensor. The CMP sensor is located in the distributor and consists of a signal generator and a signal rotor. As the signal rotor turns, a magnetic flux from the magnet is applied to the hall element repeatedly. The hall element generates a voltage that is proportional to the magnetic flux. This voltage signal is wave-shaped and is modified into a digital pulse by the comparator and sent to the Powertrain Control Module (PCM). The PCM uses this pulse/revolution signal to determine the engine speed and the position of each cylinder. The PCM uses this signal to control the fuel injectors and the ignition timing.

CONDITION FOR RUNNING THE DTC
^ The engine is being cranked.
^ The engine is running.

CONDITIONS FOR SETTING THE DTC
No signal from the CMP sensor for 3 seconds with the PCM receiving an engine start signal.

ACTION TAKEN WHEN THE DTC SETS
^ The PCM illuminates the Malfunction Indicator Lamp (MIL).
^ The PCM records the operating conditions at the time the diagnostic fails. This information is stored in the Freeze Frame buffer.

CONDITIONS FOR CLEARING THE MIL/DTC
^ The MIL turns off after 3 consecutively passing trips without a fault present.
^ A history DTC clears after 40 consecutive warm-up cycles without a fault.
^ Perform the scan tool clear DTC Information function in order to clear the DTC.

DIAGNOSTIC AIDS
Check for any of the following conditions:
^ If DTC P1500 is set, diagnose P1500 first.
^ If no problem is found with the CMP sensor or the circuitry, check the CMP sensor signal rotor for proper alignment or damage.

If a DTC P0340 is intermittent, driving the vehicle under the following conditions can verify whether the fault is present. Perform the scan tool Clear DTC Information function. Road test the vehicle while monitoring the DTC P0340 diagnostic on the scan tool under the Not Ran Since Code Cleared selection in the DTC Information menu. If a DTC P0340 appears in the Not Ran Since Code Cleared list, the P0340 diagnostic has not yet run. When the DTC P0340 does not appear in the Not Ran Since Code Cleared list, the P0340 diagnostic has run. If the MIL is NOT illuminated, and there is no Pending DTC Status in DTC Information, the P0340 diagnostic has passed. The DTCs MUST be cleared in order to view the Current Status of the Not Ran Since Code Cleared list. DO NOT forget that the Not Ran Since Code Cleared list only indicates that the test has run, not whether the test passed or failed. The DTC Information screen must be checked for Current or Pending status in order to determine the outcome of the diagnostic test involved.

An intermittent malfunction may be caused by a fault in the CMP sensor circuit. Inspect the wiring harness and components for an intermittent condition. Refer to Intermittent Conditions. Intermittent Conditions

If the DTC P0340 cannot be duplicated, the information included in the Freeze Frame data can be useful in determining the vehicle operating conditions since the DTC was first set.

TEST DESCRIPTION

Steps 1-10:

Steps 11-14:

The numbers below refer to the step numbers in the diagnostic table.
1. The Diagnostic System Check-Computers and Control Systems prompts the technician to complete some basic checks and to store the Freeze Frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.
2. This step determines if a fault is present. Review the Freeze Frame data to determine when the DTC set. Always record this information.
6. A malfunctioning starter signal circuit can cause a false DTC P0340 to set.
10. This step checks for a mechanical malfunction. Inspect for a broken timing belt if the signal rotor does not turn.