P0340

Camshaft Position (CMP) Sensor Circuit:

Circuit Description

When the distributor shaft rotates, a magnetic field is generated due to changes in the air gap between the Camshaft Position (CMP) sensor and the signal rotor. As a result, a reference voltage is induced in the CMP sensor. This reference voltage is monitored by the Powertrain Control Module (PCM) where it is used to calculate engine speed and to distinguish each cylinder, and also as one of the signals to control various devices.

Conditions for Setting the DTC

^ No signal from the CMP sensor with engine cranking.

^ Conditions present for 2 seconds.

Action Taken When the DTC Sets

^ The Malfunction Indicator Lamp (MIL) will illuminate.

^ The PCM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame buffer.

Conditions for Clearing the MIL/DTC

^ The MIL will turn "OFF" after three consecutively passing cycles without a fault present.

^ A History DTC will clear after 40 consecutive warm-up cycles without a fault.

^ DTC(s) can be cleared by using a scan tool or by disconnecting the PCM battery feed.

Diagnostic Aids

Check The Following Conditions:

^ If DTC P1500 Starter Signal Circuit is set, diagnose P1500 first. If the Starter Motor fails to operate this DTC may be stored in the memory of the PCM, even though the CMP sensor and its circuits are in good condition. When the Starter Motor fails to operate and this DTC appears, check the starter motor and its circuits first.

^ If no problem is found with the CMP sensor or the circuitry, check the CMP sensor air gap.

^ Poor connection at PCM. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection.

^ Damaged harness. Inspect the wiring harness for damage.

If 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.

If any wiring repairs need to be made, Refer to Repair Procedures in Diagrams.

Test Description

Number(s) below refer to the step number(s) on 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. Determines if fault is present. Reviews Freeze Frame data to determine when the DTC set. Always record this information. If P1500 is also set, diagnose P1500 first.

3. If temperatures are above the values listed, the CMP sensor resistance should be 240 to 325 ohms if temperature is 50° to 100°C (122° to 212°F).

8. Check the CMP sensor air gap.