Crankshaft Position Sensor: Testing and Inspection

Diagnostic Codes:
P 0335, P 0336

Monitoring Procedure
If engine position sensor (CMP) signals are detected which indicate engine rotation above a given speed without any signal from a crankshaft sensor, then a fault is present. If the crankshaft gear teeth count is incorrect by more than one tooth, then a fault event is registered and if the number of fault events exceeds the limit without the engine synchronizing then a crankshaft in- accurate fault is present.

The strategy will report to the Diagnostic Status Manager (DSM) when a crankshaft inaccurate fault is present and the DSM will then decide whether to store a fault code and illuminate the MIL Lamp.

The crankshaft position sensor (CKP) and CMP are tested by cross checking the output of the sensors and identifying when only one sensor is operating. A tooth position check will test that all tooth edges are being correctly detected and the "missing tooth" gap is present. As the CKPS is central to engine management system operation the engine cannot run with a CKPS circuit fault.

The average engine speed is measured using the camshaft sensor during stall. If the engine speed is greater than a threshold then a crankshaft position sensor fault is present.

Fig. 2 Interface Between ECM & CKPS:

Interface Between ECM And CKPS

Fig. 1 Location Of CKPS:

CKP Circuit
CKP Circuit, P 0335

Possible causes:
- Crank sensor not fitted correctly - hanging loose
- Reluctor ring fault - not fixed to crank
- Crank sensor harness open circuit or short circuit to ground
- Crank sensor fault
- ECM interface circuit fault

CKP Circuit Range/Performance
CKP Circuit Range/Performance - P 0336

The CKPS counts the number of teeth between the "missing tooth" gaps. If the tooth count is incorrect by more than one tooth, above or below the actual number of teeth, then a missing tooth fault event has occurred. If a number of fault events occur without the engine synchronizing then a crankshaft range/performance fault is present.

Possible causes:
- Damaged reluctor ring
- Magnetic debris on reluctor ring
- Radio Frequency Interference (RFI) problem with crank sensor wiring