LR3/Disco 3
Knock control disabled and a default “safe ignition map” are used.
Possible rough running and reduced engine performance.
One sensor is located in the centre of the engine valley and the other is located on the front RH side of the cylinder block.
CRANKSHAFT SPEED AND POSITION SENSOR
The Crankshaft Position Sensor (CKP) is located on the top of the transmission bell housing just to the left of the centre
line with the sensor tip adjacent to the flywheel rim. The sensor is a variable reluctance type with a resistance of 1100
Ohms +- 150 Ohms.
The sensor produces the signal which enables the ECM to determine the angle of the crankshaft, and the engine RPM.
From this, the point of ignition, fuel injection, etc. is calculated. If the signal wires are reversed a 3° advance in timing will
occur, as the ECM uses the falling edge of the signal waveform as its reference / timing point for each tooth.
The sensor picks up its signal from a reluctor ring machined into the diameter of the drive plate. The reluctor ring has 36
teeth at 10° intervals and 3° wide. One of the teeth is removed to provide a reference mark which is 60 degrees BTDC
No.1 cylinder.
The sensor operates by generating an output voltage caused by the change in magnetic field that occurs as the teeth
pass in front of the sensor. The output voltage varies with the speed of the teeth passing the sensor. The higher the
engine speed, the higher the output voltage.
The ECM transmits the engine speed over the CAN bus.
If the CKP sensor fails while the engine is running the engine will stall, misfire or run poorly and a relevant fault code will
be stored. If the engine is not running when a fault occurs then the engine will not start.
CAMSHAFT POSITION SENSOR (CMP)
The Camshaft Position Sensor (CMP) is a variable reluctance type sensor located at the front of the engine in the valve
cover above number 4 cylinder.
The CMP sensor produces one pulse for every two engine revolutions. The sensor picks up on a reluctor on the LH
camshaft.
ENGINE COOLANT TEMPERATURE SENSOR
