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: Camshaft Position Sensor "A" Circuit Bank 1 or Single Sensor
DTC P0341: Camshaft Position Sensor "A" Circuit Range/Performance Bank 1 or Single Sensor

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
5-Volt Reference Circuit | P0107, P0522, P0532, P0641, P0651 | P0340 | P0641 | --
CMP Sensor Signal Circuit | -- | P0340 | P0340 | P0341
Low Reference | -- | P0340 | P0340 | --

### Typical Scan Tool Data

#### CMP Sensor

Circuit | Normal Range | Short to Ground | Open | Short to Voltage
--- | --- | --- | --- | ---
Operating Conditions: Engine Running
5-Volt Reference Circuit | 400-6,400 RPM | 0 RPM | 0 RPM | 0 RPM
CMP Sensor Signal Circuit | 400-6,400 RPM | 0 RPM | 0 RPM | 0 RPM
Low Reference | 400-6,400 RPM | 0 RPM | 0 RPM | 0 RPM

### Circuit/System Description

The camshaft position (CMP) sensor works in conjunction with the 4X reluctor trigger wheel on the sprocket face of the camshaft actuator assembly. The reluctor trigger on the camshaft actuator gear contains a pattern around the circumference, consisting of 2 narrow teeth and 2 wide teeth. The engine control module (ECM) provides a 5-volt reference to the sensor, as well a low reference and signal circuit. As the camshaft rotates, the reluctor trigger wheel interrupts a magnetic field provided by a magnet internal to the sensor. The CMP sensor internal circuitry detects this interruption of the magnetic field and produces an ON/OFF DC voltage of varying frequency. The frequency of the CMP sensor output signal is dependent upon the speed of the camshaft. The information from the CMP sensor and other engine sensors is used to determine the optimum fuel injection and ignition system timing events for efficient engine operation. The ECM will recognise the narrow and wide tooth patterns to identify camshaft position, or which cylinder is in compression and which is in exhaust. The ECM also uses the CMP sensor output information to determine the camshaft relative positive to the crankshaft position, cylinder misfire and if equipped, to control intake and exhaust valve timing through the camshaft actuator.

### Conditions for Running the DTC

• | DTC P0335, P0336, P0641 or P0651 is not set.

• | The engine is cranking or running.

• | The DTC runs continuously when the above conditions are met.

### Conditions for Setting the DTC

#### P0340

| Important: The ECM detects engine movement by sensing that airflow through the mass air flow (MAF) sensor is more than 3 g/s, or by sensing CMP sensor pulses.

• | The ECM detects that the starter is commanded ON and the engine has been cranking for more than 4 seconds without a CMP sensor pulse.

• | The ECM detects that the engine has started, but has not received a CMP sensor pulse during the first engine revolution.

• | The ECM detects that the engine is running, but has not received a CMP sensor pulse for 800 out of 1,000 engine revolutions.

#### P0341

Important: The ECM detects engine movement by sensing that airflow through the MAF sensor is more than 3 g/s, or by sensing CMP sensor pulses.

The ECM detects that the engine has started, but has received either of the following during the first engine revolution:

• | Less than or more than 4 CMP sensor pulses, if equipped with an automatic transmission.

• | Less than four or more than eight CMP sensor pulses, if equipped with a manual transmission.

• | The ECM detects that the engine is running, but receives less than 398 CMP pulses or more than 402 CMP pulses per 100 engine cycles in 800 of 1000 engine cycles.

### Conditions for Setting the DTC

DTCs P0340 or P0341 are Type B DTCs.

DTCs P0340 or P0341 are type B DTCs.

### Conditions for Clearing the MIL/DTC

DTCs P0340 or P0341 are type B DTCs

### Diagnostic Aids

• | This test procedure requires that the vehicle battery has passed a load test and is completely charged.

• | When disconnecting harness connectors or removing fuses and relays from a fuse block, always inspect the component electrical terminals for corrosion and the mating electrical terminals for tightness.

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Connector End View Reference

Component Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Control Module References

### Circuit/System Verification

1. With the engine running, using a scan tool observe the Engine Speed parameter and the Camshaft Position (CMP) sensor parameter. The CMP sensor parameter should closely match the Engine Speed parameter.

⇒ | If the CMP sensor is zero or grossly different from the Engine Speed parameter then continue with the Circuit/System Testing.

2. Ignition ON, engine OFF, use the live plot function on the scan tool. Select the Engine Speed parameter and the CMP Sensor parameter. Change the minimum spec to 400 RPM for both parameters. Change the maximum spec to 4,000 RPM for both parameters.
3. Start the engine.
4. Observe the scan tool.
5. Quickly accelerate and release the accelerator pedal several times. Do not accelerate past 4,000 RPM. The 2 graph lines on the live plot display should track together across the screen.

⇒ | If the CMP sensor plot line changes from the Engine Speed plot line continue with the Circuit/System Testing.

⇒ | If the vehicle passes the above Circuit/System Verification Tests, 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 Data List. Another option is to refer to Testing for Intermittent Conditions and Poor Connections.

### Circuit/System Testing

1. Ignition OFF, inspect the CMP sensor engine wire harness circuits for the following conditions:

• | Close routing of secondary ignition wires.

• | Close routing of aftermarket electrical equipment.

• | Close to motors, solenoids and relays.

⇒ | Correct any wire routing or component placement conditions if determined to be a possible source of electrical interference.

2. Disconnect the CMP sensor wire harness connector. Inspect the harness connector for corrosion and for correct terminal tension. Repair as necessary.
3. Ignition ON, engine OFF. Measure for 4.8-5.2 volts between the 5-volt reference circuit at the CMP wire harness connector and a known ground.

⇒ | If the voltage is less than 4.8 volts, test for a short to ground or an open/high resistance in the 5-volt reference circuit between the ECM and the CMP sensor connector. If the circuit tests normal, replace the ECM.

4. Ignition ON, engine OFF. Measure for 4.8-5.2 volts at the connector between the CMP sensor signal circuit and a known ground.

⇒ | If the voltage is less than 4.8 volts, test for an short to ground or an open/high resistance in the CMP sensor signal circuit between the ECM and the CMP sensor wire harness connector. If the circuit tests normal, replace the ECM.

⇒ | If the voltage is more than 5.2 volts, test for a short to voltage in the CMP sensor signal circuit between the ECM and the CMP sensor connector. If the circuit tests normal, replace the ECM.

5. Ignition ON, engine OFF. Measure for 1-3 mA of current between the CMP sensor signal circuit and a known ground at the CKP wire harness connector.

⇒ | If the amperage is more than 3 mA, test the CMP sensor signal circuit for a short to the 5-volt reference circuit between the ECM and the CMP sensor connector. If the circuit tests normal, replace the control module.

6. Connect a 3-A fusible link wire to a known ground.
7. Ignition ON, engine OFF. Observe the CMP Active Counter parameter on the scan tool.
8. Touch the fusible link to the CMP sensor signal circuit repeatedly at the connector. The CMP Active Counter parameter should increment.

⇒ | If the CMP Active Counter parameter does not increment, replace the ECM.

9. Ignition ON, engine OFF. Measure for B+ at the low reference circuit on the CMP sensor and the battery positive post.

⇒ | If the voltage measured between the low reference circuit and the battery positive post is not the same as the voltage measured between a known ground and the battery post, then test for an open/high resistance in the low reference circuit between the ECM and the CMP sensor connector. If the circuit tests normal, replace the ECM.

10. Ignition OFF, inspect the CMP sensor for looseness. Remove the CMP sensor from the engine. Inspect the CMP sensor and the O-ring for damage. Refer to Camshaft Position Sensor Replacement. Replace the CMP sensor.
11. Reconnect the CMP wire harness connector to the CMP sensor.
12. Ignition ON, engine OFF.
13. While observing the CMP Active Counter parameter on the scan tool, pass a small flat steel object by the tip of the CMP sensor repeatedly. The CMP Active Counter parameter should increment.

⇒ | If the parameter remains at zero or another fixed value, replace the CMP sensor.

14. Ignition OFF, remove the engine oil pan. Refer to Oil Pan Replacement and inspect the engine oil for debris and the crankshaft reluctor wheel for damage or debris stuck onto the teeth of the reluctor wheel.

⇒ | If debris is found in the engine oil, inspect the engine components to determine the cause.

⇒ | If the crankshaft reluctor wheel is damaged, replace the crankshaft.

15. Ignition OFF, remove the engine front cover. Refer to Engine Front Cover Replacement . Inspect the timing chain, tensioner and sprockets for wear or damage. Refer to Camshaft Timing Chain and Sprocket Cleaning and Inspection.

⇒ | If any parts are worn or damaged, replace as necessary.

### 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