The Camshaft Position Sensor (CMPS) is a sensor that detects the compression TDC of the NO. 1 cylinder. The CMPS consists of a hall type sensor and a target on the end of the intake camshaft. When the target triggers the sensor, the sensor voltage is 5V. If not, the sensor voltage is 0V. These CMPS signal is sent to the PCM and the PCM uses the CMPS signal for synchronizing the firing of sequential fuel injectors.
Checking oputput signals from CMP during engine running, if the expected number of cam tooth count is not observed, PCM sets P0391.
Item
Detecting Condition
Possible cause
DTC Strategy
Signal check
Poor connection
Short in harness
Electrical noise
Target wheel
CMPS(B2-Exhaust)
PCM
Enable Conditions
Reference mark found
No CKP sensor error
No 1 tooth off error
Threshold value
Unplausible signal counter > 10 times
Diagnosis Time
Continuous
MIL On Condition
2 driving cycles
Fig.1) Normal waveform of IN-CMPS & EX-CMPS at idle.