A Crankshaft Position Sensor (CKPS) is a magnetic type sensor that generates voltage using a sensor and a target wheel mounted on the crankshaft; there are 58 slots in the target wheel where one is longer than the others. When the slot in the wheel aligns with the sensor, the sensor voltage outputs low. When the metal (tooth) in the wheel aligns with the sensor, the sensor voltage outputs high. During one crankshaft rotation there are 58 rectangular signals and one longer signal. The ECM calculates engine RPM by using the sensor’ s signal and controls the injection duration and the ignition timing. Using the signal differences caused by the longer slot, the ECM identifies which cylinder is at top dead center.
If the number of input signal between the standard positions is smaller(or larger) than the normal value over 7 times, or If there is no signal from CKPS while there is CMPS signal, ECM sets DTC P0727.
Item
Detecting Condition
Possible Cause
DTC Strategy
Signal check
Poor connection
Open or short in signal circuit
CKPS
Case1
Enable
Conditions
Vehicle speed < 1kph or >25kph
Engine speed > Idle speed
Threshold Value
1 less tooth detected
Diagnostic Time
More than 7 times
Case2
1 more tooth detected
Case3
There is no malfunction on CMPS.
No signal over 8 times during cranking
No signal over 10 times after cranking
Continuous
MIL ON
Condition
No
This example shows a typical Crankshaft Position Sensor(CKPS) and Camshaft Position Sensor(CMPS) waveform at idle. The ECM controls the injection and ignition timing by using these signals. Generally CKPS signal is used to detect the piston’s position and CMPS signal is used to detect the Top Dead Center of each cylinder.