Question about 2002 Jeep Grand Cherokee
DTC P0340 - Camshaft Position Sensor Circuit Malfunction
This indicates that a problem was detected in the camshaft position sensor circuit. Since it says circuit, that means the problem could lie in any part of the circuit - the sensor itself, the wiring, or the PCM. Don't just replace the CPS (camshaft position sensor) and think that will definitely fix it.
Symptoms can include:
Hard starting or no start
Rough running / misfiring
Loss of engine power
A code P0340 could mean one or more of the following has happened:
a wire or connector in the circuit could be grounded/shorted/broken
the camshaft position sensor may have failed
the PCM may have failed
there exists an open circuit
the crankshaft position sensor may have failed
With a P0340 OBD-II trouble code, diagnosis can be tricky at times. Here are some things to try:
Visually inspect all the wiring and connectors in the circuit
Check for continuity in the circuit wiring
Check the operation (voltage) of the camshaft position sensor
Replace the camshaft position sensor as required
Check the crankshaft position circuit as well
Replace circuit wiring and/or connectors as required
Diagnose/replace the PCM as required
Monitor CMP sensor signal on a labscope looking for electrical noise that shows up on the pattern along with the CMP sensor Analog Current (AC) voltage sign wave signal.
Check timing belt alignment specific to the auxiliary shaft gear. There is a diamond on the gear that should align with a diamond on the rear belt cover just above the gear.
If electrical noise is present on the sensor signal, disconnect one coil pack at a time and disconnect the voltage regulator connection on the alternator to identify if the added electrical noise on the CMP signal pattern cleans up indicating the source of the electrical noise.
If no added electrical noise is present on the pattern and the timing gears are properly aligned, check the Dark Blue/Orange (DB/O) wire to verify it is not open between the sensor and PCM pin 85.
Also check the Grey/Red (GY/R) wire to verify it is providing a ground
In checking timing belt alignment, the auxiliary shaft sprocket has a diamond that should align with a diamond on the timing cover at the 12:00 position of the sprocket when the camshaft and crankshaft gears are at the top dead center position. If the Camshaft Position (CMP) sensor signal shows electrical noise on the labscope, disconnect the voltage regulator connection, and the coil packs individually to see if the electrical noise on the signal cleans up pinpointing the area of failure. If electrical noise cleans up when disconnecting a coil pack, remember that any of that pack's plug wires or the pack itself may be causing the noise.
Hope helps (remember to rate and comment this answer)..
Posted on Sep 25, 2011
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