Mechanics

CAMSHAFT POSITION SENSOR

1999 Saturn SC2 • 4 cylinder FWD Automatic • 140,000 miles

My check engine light comes on and my scanner shows p0340-no camshaft position sensor at powertrain control module. When I turn the light off, sometimes it stays off for days and sometimes it comes on several times a day. The car always starts and runs well.I wouldnt know about the problem if not for the check light. Any suggestions?Where are the sensors located?
Avatar
Bensjets
March 31, 2011.



There is no cam sensor on that engine I posted the code description for that code. Most of the time the problem is just spark plugs and wires setting that code. There is a black carbon that build's up where the spark plug wire meets the plug's I would also see if the coil towers where the plug wire's go on are corroded.I would start by checking those things first. Use a bright flash light to see if the spark plug boots have black carbon in them.

The electronic ignition (EI) module supplies a signal to the PCM whenever it determines that #4 cylinder fired on its compression stroke. Because of opposite coil tower polarity, the simultaneous fire of #1 and #4 cylinders are of opposite polarity as well. Under most conditions (except decel), the waste spark cylinder fires before the compression cylinder in sequence. The EI module can determine this polarity sequence and voltage amplitude by using capacitive pickup plates located under the 1/4 coil. If the module senses a positive to negative sequence and high negative spike when #4 is on DTC, it pulls the PCM cam signal to ground signaling that #4 has just fired on compression. This signal along with the double pulse received from the CKP sensor, synchronizes spark and fuel timing.

DTC PARAMETERS
DTC P0340 will set if the PCM voltage on cylinder #4 signal wire is not pulled to ground (cam signal pulse) when: * The engine has been cranking for 5-10 seconds; or
* The engine is running.

IMPORTANT: The cam signal is continuously checked when crankshaft sensor pulses are received by the PCM, except under deceleration.

DIAGNOSTIC AIDS

IMPORTANT: A cam pulse missing may not affect engine operation.

* An open or high resistance on #1 plug wire or plug will result in P0340 setting.
* Inspect EIS towers and plug wire connections for corrosion or other signs of poor retention at connections.

Saturntech9
Mar 31, 2011.
Louie, Is this you?I changed the plug wires which were two years old. The check engine light hasnt come on since.(5days)Once again you know your stuff.I thought you were with Edmunds at one time. Saturntech9, thanks so very much.

Tiny
Bensjets
Apr 10, 2011.
Yes this is louie glad to hear you got it all fixed. So what is edmunds?

Saturntech9
Apr 11, 2011.
Edmunds is another company like 2CARPROS. Thanks again my friend.

Tiny
Bensjets
Apr 12, 2011.
Your welcome anytime you need help hit me up.

Saturntech9
Apr 12, 2011.