LR3/Disco 3
CRANKSHAFT POSITION SENSOR (CKP)
The crankshaft position sensor is mounted at the rear underside of the engine near the transmission bell housing.
Connection between the sensor and the harness is via a link harness and a two-way connector. Both wires go directly to
the ECM. 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 electronics within the ECM uses the falling edge of the signal waveform as its reference / timing
point for each tooth.
The reluctor is pressed into the flywheel and has a "tooth" pattern based on 36 teeth at 10° intervals and approximately 3°
wide: one of the teeth is removed to provide a hardware reference mark which is 60 degrees BTDC No.1 cylinder.
Because of the crankshaft sensor's orientation, the target wheel uses windows machined into the face, rather than actual
teeth.
The sensor operates by generating an output voltage caused by the change in magnetic field that occurs as the windows
pass in front of the sensor. The output voltage varies with the speed of the windows passing the sensor, the higher the
engine speed, the higher the output voltage. Note that the output is also dependent on the air gap between the sensor
and the teeth (the larger the gap, the weaker the signal, the lower the output voltage). The ECM transmits the engine
speed to other vehicle ECU's on CAN.
CAMSHAFT POSITION SENSOR (CMP)
20
Fuel pump control
Output
21
Not used
-
22
Not used
-
23
Not used
-
24
APP sensor 1 signal
Output
25
Not used
-
26
Brake light switch
Input
27
Not used
-
28
Not used
-
29
Not used
-
30
Ignition switch
Input
31
CAN +
Input
32
APP sensor 1 power
Output
33
DMTL
Output
34
Not used
-
35
Cruise switch -
Output
36
Cruise switch +
Input
