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 PCM 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 PCM identifies which cylinder is at top dead center.
If the number of input signal between the standard positions is larger than the normal value over 7 times, PCM sets DTC P0338.
Item | Detecting Condition | Possible Cause |
DTC Strategy | ● Reference mark check | ● Poor connection ● Open or short in signal circuit ● CKPS |
Enable Conditions | ● Vehicle speed < 1kph or >25kph ● Engine speed > Idle speed | |
Threshold Value | ● 1 more tooth detected | |
Diagnostic Time | ● More than 7 times | |
MIL ON Condition | ● 2 driving cycle |
This example shows a typical Crankshaft Position Sensor(CkPS) and Camshaft Position Sensor(CMPS) waveform at idle. The PCM 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.
