P0340

Circuit Description
The powertrain control module (PCM) receives voltage pulses from the camshaft position (CMP) sensor. The PCM uses these pulses as reference signals indicating engine speed and number 1 cylinder identification. The CMP sensor generates the voltage pulses from the rotation of the distributor shaft. A signal rotor, which rotates with the distributor shaft, passes through the air gap of the CMP sensor. The movement of the signal rotor through the air gap creates a flux in the magnetic field generated by the CMP sensor. The CMP sensor responds to the change in the magnetic field and sends this information to the PCM.

Conditions for Setting the DTC
^ No signal from the CMP sensor while cranking the engine.
^ The condition present for 2 seconds.

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 three consecutively passing trips without a fault present.
^ A History DTC clears after 40 consecutive warm-up cycles without a fault.
^ Use the scan tool Clear DTC Information function or disconnect the PCM battery feed in order to clear the DTC.

Diagnostic Aids
Check for any of the following conditions:
^ Check for a DTC P1500 Starter Signal Circuit and if found, diagnosis the DTC P1500 first. A starter motor that fails to operate normally may set a DTC P0340. Check the starter motor and starter motor circuits if a DTC P0340 is set and there are problems with the operation of the starter motor.
^ Check the CMP sensor signal rotor for proper alignment and damage.
^ Check for faulty electrical connections at the PCM and circuit components.
^ Inspect the wiring harness for damage or electrical faults.
For proper electrical circuit repair procedures, refer to Diagrams.
If a DTC P0340 cannot be duplicated, the information included in the Freeze Frame data can be useful in determining vehicle operating conditions when the DTC was first set.

Test Description
The numbers below refer to the step numbers in the Diagnostic Table.
1. The Powertrain OBD System Check prompts the technician to complete some basic checks and 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 fault is present.
3. The CMP sensor resistance can range from 185 ohms to 325 ohms at -10°C to 100°C (14°C to 212°F).
8. This step checks the CMP sensor for the correct air gap.