Cam Shaft Position Sensor (CMPS) is hall sensor type. Sensing the teeth attatch at the end of 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 CMPS signal does not generate while CKPS signal is outputted for the duration that crank shaft rotates 4 times. 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 | ● During accelerating and turning engine "ON" | |||
Threshold Value | ● CKPS signal is outputted while CMPS signal does not generate. | |||
Diagnostic Time | ● Crank Shaft rotates 4 times | |||
Fail Safe | Fuel Cut | YES | ||
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 | 1.25mm | Below 2.0V | Above 3.8V |
※ Signal 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.
