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 Descriptor

DTC P0337: Crankshaft Position (CKP) Sensor Circuit Low Duty Cycle

### Circuit/System Description

The crankshaft position (CKP) sensor is located on the rear of bank 1 of the engine block. The CKP sensor produces an AC voltage of different amplitude and frequency depending on the velocity of the crankshaft. The CKP sensor works in conjunction with a 58X reluctor wheel that is attached to the crankshaft. Each tooth on the reluctor wheel are spaced 6 degrees apart with one span having a 12 degree space. The engine control module (ECM) uses the 12 degree space to determine top dead center (TDC) for cylinders 1 and 4. The ECM determines when cylinder 1 is on the compression stroke by monitoring the CKP sensor and the camshaft position (CMP) sensors. The ECM can synchronize the ignition timing, fuel injector timing and spark knock control based on the CKP sensor and the CMP sensor inputs. If the ECM loses the reference position to TDC, or the CKP signal is lost or erratic, one of these DTCs sets.

### Conditions for Running the DTC

• | The engine is cranking or operating.

• | The ECM has detected more than 12 camshaft revolutions.

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

### Conditions for Setting the DTC

The ECM detects a difference of more than 8 teeth between reference gap position pulses for 4 consecutive crankshaft revolutions in which the same number of pulses are detected each crankshaft revolution.

### Action Taken When the DTC Sets

DTC P0337 is a type A DTC.

### Conditions for Clearing the DTC

DTC P0337 is a type A DTC.

### Diagnostic Aids

The following conditions could also set the DTCs:

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

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

• | Incorrect installation of the CKP sensor or the reluctor wheel.

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

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

• | The ECM uses the camshaft position sensors to determine engine speed and position when there is a CKP sensor condition.

• | The engine will operate with a CKP sensor condition only if the ECM has stored the learned reference position of the camshafts in memory. With a crankshaft position sensor condition the engine will go into a limp home mode after a hard restart. The ECM then calculates engine speed from one of the camshaft position sensors. During a limp home mode the following additional DTCs may set and should be ignored:

- | DTC P0324 Knock Sensor (KS) Module Performance.

- | DTC P1011 Intake Camshaft Position Actuator Park Position Bank 1.

• | An intermittent condition in the camshaft position (CMP) sensor circuits can cause a CKP DTC to set. Inspect the CMP sensor, harness connections, and related wiring, if you suspect this condition.

### 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. Ignition ON, clear the DTC Info with a scan tool. Attempt to start the engine, observe the DTC information with a scan tool. DTC P0335, P0336, and P0338 should not set.
2. Move related harnesses/connectors of the CKP sensor and verify the engine does not stumble, stall or change engine speed.
3. 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, remove the ECM Fuse/relay that supplies B+ to the ECM.
2. Disconnect the harness connector at the appropriate CKP 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 ECM or the sensor may be damaged if the circuit is shorted to B+ voltage.

3. Test for 5 ohms or less between the low reference circuit and a known ground.

⇒ | If greater than 5 ohms, test the low reference circuit for an open/high resistance or for a short to voltage. If the circuit/connections test normal, replace the ECM.

4. Install the ECM fuse that supplies B+ to the ECM.
5. Ignition ON, measure for 4.8-5.2 volts between the 5 volt reference circuit of the CKP sensor harness connector and a known ground.

⇒ | If less than 4.8 volts, test the 5 volt reference circuit for a short to ground or an open/high resistance. If the circuits/connections test normal, replace the ECM.

⇒ | If more than 5.2 volts, test the 5 volt reference circuit for a short to voltage. If the circuits/connections test normal, replace the ECM.

6. Measure for 4.8-5.2 volts between the signal circuit of the CKP sensor harness connector and a known ground.

⇒ | If the voltage is greater than 5.2 volts, test for a short to voltage in the signal circuit of the CKP sensor. If circuit/connections test normal, replace the ECM.

⇒ | If the voltage is less than 4.8 volts, test for a short to ground or an open/high resistance in the signal circuit of the CKP sensor. If circuit/connections test normal, replace the ECM.

7. If all circuits/connections test normal, replace the CKP sensor.

### Repair Instructions

Perform the Diagnostic Repair Verification.

• | Crankshaft Position Sensor Replacement

• | Engine Control Module Replacement for engine control module replacement, setup and programming.