Cam Shaft Position Sensor (CMPS) is hall sensor type. Sensing the teeth attach at the end of cam shaft, CMPS detects rotation of Cam shaft. (1 signal per 1 rotation) As Cam shaft rotates once while Crank shaft does twice, CMPS reference 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.
P0341 is set corresponding to the condition of ECM internal counter when CMPS reference point is detected more or less than twice while CKPS reference point is recognized 4 times. This code is due to temporary poor connection or short to ground in CMPS circuit, CMPS component failure.
Item | Detecting Condition | Possible Cause | ||
DTC Strategy |
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Signal monitoring |
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CMPS circuit
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CMPS | ||
Enable Conditions |
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During accelerating and turning engine ON | |||
Threshold Value |
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When RPM from CMPS correlates with RPM from CKPS abnormally. | |||
Diagnostic Time |
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Corresponding to ECM internal counter condition. | |||
Fail Safe | Fuel cut | NO |
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When CKPS failure, backup mode starts using only CMPS.
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When CMPS failure, backup mode starts using only CKPS.
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When Both CKPS and CMPS simultaneous failure, engine off | |
EGR Off | NO | |||
Fuel Limit | NO | |||
Check Lamp | ON | |||
Sensor Type | Output Signal Characteristic | Air Gab | LOW Signal Detecting Voltage | HIGH Signal Detecting Voltage |
Hall effect type | 0V ~ 5V Digital signal output | 0.5 ~1.5 mm | Below 2.0V | Above 3.8V |
Fig.1) This shows waveform of CKPS and CMPS simultaneously. The middle area indicates reference points of CKPS and CMPS.
☞ Injection sequence is determined based on Low and High signal of CMPS reference point as detecting cylinder position.
CMPS signal waveform analysis.
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.
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.
