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 provides an overview of each diagnostic category.

### DTC Descriptors

DTC P0340 28: Camshaft Position Sensor Circuit Incorrect Frequency
DTC P0340 29: Camshaft Position Sensor Circuit Too Few Pulses

### 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.

### Conditions for Running the DTC

• | DTCs P0016, P0335 and P0336 are not set.

• | The engine is running.

• | The engine speed is greater than 50 RPM.

• | The DTCs run continuously once the above conditions are met.

### Conditions for Setting the DTC

The ECM detects too few, or an incorrect amount, of CMP pulses.

### Action Taken When the DTC Sets

DTC P0340 is a Type B DTC.

### Conditions for Clearing the DTC

DTC P0340 is a Type B DTC.

### 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

Component Connector End Views

#### 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

Control Module References for scan tool information

### Circuit/System Verification

1. Engine running, observe the DTC information with a scan tool. DTC P0340 should not set.
2. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

### Circuit/System Testing

1. Ignition OFF, and the MAIN fuse removed, disconnect the harness connector at the B23 CMP sensor.
2. Test for less than 5 Ω between the low reference circuit terminal 2 and ground.

⇒ | If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit/connections test normal, replace the K20 ECM.

3. Install the MAIN fuse. Ignition ON, verify that a test lamp illuminates between the ignition 1 voltage circuit terminal 3 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. Ignition ON, test for 4.8-5.2 V between the signal circuit terminal 1 and ground.

⇒ | If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 ECM.

⇒ | If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.

5. If all circuits test normal, test or replace the B23 CMP sensor.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Camshaft Position Sensor Replacement

• | Control Module References for ECM replacement, setup, and programming