P0340

DTC P0340 Camshaft Position (CMP) Sensor Circuit:

Camshaft:

CIRCUIT DESCRIPTION

The Camshaft Position (CMP) sensor is located in the distributor and consists of a signal generator (hall element and magnet) and signal rotor. As the signal rotor turns, a magnetic flux from the magnet is applied to the hall element intermittently. The hall element generates the voltage in proportion with the magnetic flux. This voltage is wave-shaped into a pulse (sensor signal) by the comparator and sent to the ECM. Receiving this pulse (4 pulse/revolution), the ECM detects engine speed and position of each cylinder. The ECM uses this signal to control the fuel injectors and ignition timing.


CONDITIONS FOR SETTING THE DTC


- No signal from the CMP sensor for 3 seconds with the ECM receiving an engine start signal.


ACTION TAKEN WHEN THE DTC SETS

- The Malfunction Indicator Lamp (MIL) will illuminate.

- The ECM 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 "0FF" after three consecutive drive cycles without a fault present.

- A 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 ECM battery feed.


DIAGNOSTIC AIDS

Check the following conditions:


- If DTC P1500 Starter Signal Circuit is set, diagnosis P1500 first.

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

- Poor connection at ECM. Inspect harness connectors for backed Out terminal, 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 since the DTC was last set. This may assist in determining how often the DTC sets.


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 Engine 0BD 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. Determine if fault is present. Review Freeze Frame data to determine when the DTC set. Always record this information.

5. Line one of the signal rotors up with the hall element by turning the crankshaft until one of the rotors are in the proper position.

6. Move the crankshaft just enough so the signal rotor is not in line with the hall element.