For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provide an overview of each diagnostic category.

### DTC Descriptor

DTC P0340: Camshaft Position (CMP) Sensor Circuit
DTC P0341: Camshaft Position (CMP) Sensor Performance
DTC P0342: Camshaft Position (CMP) Sensor Circuit Low Voltage
DTC P0343: Camshaft Position (CMP) Sensor Circuit High Voltage

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Ignition 1 Voltage | P0340, P0341, P0342, P0455, P0489 | P0342, P0343 | -- | P0341
Signal | P0342 | P0343 | P0343 | P0341
Low Reference | -- | P0343 | -- | P0341

### Circuit/System Description

The camshaft position (CMP) sensor correlates the crankshaft to camshaft position so that the engine control module (ECM) can determine which cylinder is ready to be fueled by an injector. As the camshaft rotates, the reluctor wheel interrupts a magnetic field produced by a magnet within the sensor and sends a signal to the ECM through the signal circuit. The CMP sensor circuits are directly connected to the ECM. The CMP sensor also determines which cylinder is misfiring. The CMP sensor circuits consist of the following:

• | An ignition 1 voltage

• | A low reference

• | A CMP signal

### Conditions for Running the DTC

• | The engine is operating.

• | The DTCs run continuously once the above condition is met.

### Conditions for Setting the DTC

#### P0340

The ECM detects no pulses from the CMP sensor.

#### P0341

The ECM detects that the CMP sensor signal voltage is erratic.

#### P0342

The ECM detects that the CMP sensor signal voltage is always low and the ECM detects no pulses from the CMP sensor.

#### P0343

The ECM detects that the CMP sensor signal voltage is always high and the ECM detects no pulses from the CMP sensor.

### Action Taken When the DTC Sets

DTCs P0340, P0341, P0342, and P0343 are Type B DTCs.

### Conditions for Clearing the DTC

DTCs P0340, P0341, P0342, and P0343 are Type B DTCs.

### Diagnostic Aids

The following conditions can also set the DTC:

• | Physical damage to the CMP sensor or the reluctor wheel.

• | Excessive play or looseness of the CMP sensor or the reluctor wheel.

• | Improper installation of the CMP sensor or the reluctor wheel.

• | Foreign material passing between the CMP sensor and the reluctor wheel.

• | Excessive air gap between the CMP sensor and the reluctor wheel.

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Connector End View Reference

• | Engine Control Module Connector End Views

• | Engine Controls Connector End Views

#### Description and Operation

Electronic Ignition (EI) System Description

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

#### Scan Tool Reference

• | Scan Tool Data List

• | Scan Tool Data Definitions

• | Scan Tool Output Controls

### Circuit/System Verification

1. Engine idling, observe the scan tool DTC information parameter. DTCs P0340, P0341, P0342, and P0343 should not set.
2. If the vehicle passes the Circuit/System Verification test, then operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records List.

### Circuit/System Testing

1. Ignition OFF, and the MAIN fuse removed, disconnect the harness connector at the CMP sensor.

Notice: Do NOT use a test lamp to test the continuity of the circuit. Damage to the control module may occur due to excessive current draw.

Important: The control module or the sensor may be damaged if the circuit is shorted to B+ voltage.

2. Test for less than 10 ohms of resistance between the low reference circuit and ground.

⇒ | If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.

3. Install the MAIN fuse. Ignition ON, verify that a test lamp illuminates between the ignition 1 voltage circuit and ground.

⇒ | If the test lamp does not illuminate, test the ignition 1 voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition 1 voltage circuit fuse is open, test all components connected to the ignition 1 voltage circuit and replace as necessary.

4. Test for 10 - 12 volts between the signal circuit and ground.

⇒ | If less than the specified range, test the low reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.

5. Verify that a test lamp does not illuminate between the signal circuit and ground.

⇒ | If the test lamp does not illuminate, test the signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.

6. If all circuits test normal, test or replace the CMP sensor.

### Repair Instructions

Perform the Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Camshaft Position Sensor Replacement

• | Control Module References for engine control module replacement, setup, and programming