Cam Shaft Position Sensor(CMPS) is hall sensor type. Sensing the teeth attatch at the end of exhaust cam shaft, CMPS detects rotation of Cam shaft (1 signal per 1 lotation).
As Cam shaft rotates once while Crank shaft does twice, CMPS referrence point generates once while CKPS' do twice.
As this signal inputted to ECM, it distinguishes crank angle and the cylinder which requires fuel injection in order to determine injection sequence and duration.
P0340 is set when CKPS signal is outputted while CMPS signal does not generate for more than 0.7 sec.. This code is due to the failure relevant to CMPS related circuit and sensor component.
Item
Detecting Condition
Possible Cause
DTC Strategy
Signal monitoring
CMPS circuit
CMPS component
Enable Conditions
Engine running(during accelerating)
Threshold Value
CKPS signal is outputted while CMPS signal does not generate.
Diagnostic Time
700ms
Fail Safe
Fuel Cut
NO
Engine does not turn "ON" at starting.
EGR Off
Fuel Limit
YES
Check Lamp
Sensor Type
Output Signal Characteristic
Air Gab
LOW Signal Detecting Voltage
HIGH Signal Detecting Voltage
Hall effect type
0V~5V Digital signal output
1.25mm
Below 2.0V
Above 3.8V
Fig.1) This shows waveform of Crank Shaft Position Sensor and Cam Shaft Position Sensor simulatneously. The middle area
indicates reference points of Crank Shaft Position Sensor and Cam Shaft Position Sensor.
Fig.2) Crank Shaft Position Sensor and Cam Shaft Position Sensor signal are measured simultaneously. Cam Shaft Position Sensor
signal is outputted once when Crank Shaft Position sensor signal is outputted twice. LOW and HIGH output of Cam Shaft
Position sensor reference point is detected at Crank Shaft Position sensor reference point.
( Injection sequence is determined based on LOW and HIGH signal of Cam Shaft Position Sensor reference point as detecting cylinder position.)
1) ECM recognizes HIGH signal as LOW signal when CMPS signal drops below 2.0V and LOW signal as HIGH signal
when CMPS signal rises above 3.8V.
2)V0 - the Minimum voltage of LOW signal does not drop below 0.0V due to the hall sensor inside resistance. When the Minimum voltage of
LOW signal is above 0.6V during signal waveform inspection, check excessive resistance inside of CMPS component or in ground circuit.