Camshaft Sensor

Tiny
BVHAWLIN
  • MEMBER
  • 2001 SATURN SC2
I am looking through my Haynes Manual, but it does not show me where the camshaft sensor is. My code was P0341
Friday, May 7th, 2010 AT 2:12 PM

5 Replies

Tiny
BLUELIGHTNIN6
  • MECHANIC
  • 16,542 POSTS
Your vehicle doesn't actually have a camshaft sensor, it uses the electronic ignition module to send the signals that the cam sensor normally sends.

This model does not use a camshaft position sensor.

The following is from DTC P0341.
The EI module uses capacitive pickup plates located under the 1/4 coil pack to determine the polarity sequence and voltage amplitude of the cylinder 1/4 secondary ignition. The PCM supplies 5 volts on the signal line and expects to see the cylinder #4 signal wire go low after every 14 crankshaft pulses (2 revolutions). This is used to determine the position of the camshaft, except under decel. The PCM only uses the transition from 5 to 0 volts as a valid TDC compression #4 cylinder signal.

For diagnostic purposes, follow the steps below.

Step 1: remove secondary wires from spark plugs; keep the wires on the coil. Measure resistance from #1 wire to #4 wire and then #2 wire to #3 wire. Resistance should be 11k ohms to 45k ohms(YIKES that's a wide range)

If resistance is in spec, go to step 2, if not in specs, go to step 3

Step 2: remove secondary wires from the coil packs and check for corrosion on the towers and wires.

If there is corrosion, go to step 4

if not, go to step 5

Step 3: remove secondary wires from the coil packs and check for corrosion on the towers and wires.

If there is corrosion, go to step 4

if not, go to step 6

Step 4: Replace or clean coils and/or wires as necessary. Retest to confirm.

Step 5: Remove spark plugs. Check for carbon or abnormal wear and proper gap (0.040 in)

If plugs check out good, go to step 8.

If the plugs are bad, replace as needed and retest to confirm.

Step 6: Measure resistance of individual secondary wires. Specs are 1.5k ohms to 15k ohms (that's what this chart says, but my knowledge says 8k ohms is normal, greater than 12k ohms should be replaced)

If wires are in spec, go to step 7

If wires are bad, replace as needed and retest to confirm

Step 7: Measure resistance from tower to tower on the coil packs (hold tight for good reading). Spec is 8K to 15K.

If coils are in spec, go back up to step 5

If coils are bad, replace as needed and retest to confirm

Step 8:(90% of the time I'll bet the problem is solved by now) Start engine. Perform under hood visual inspection of the ignition system, check for arcing (best done in a dark area, if you are inside a garage, be sure the exhaust is vented). Wet DIS module, coils, and secondary wires with salt water to provide optional ground path (arcing from the wire boot to the valve cover is possible, but would be hidden)

If arcing is present, replace wires or coils as needed and retest to confirm.

If not, go to step 9.

Step 9: Turn ignition off, back probe J3D03 (Circuit 633, brn/wht wire) at PCM with voltmeter. Connect other lead to ground. Turn ignition on, engine off and measure voltage.

Less then 4.5 volts, go to step 10
4.5-5.5 volts, go to step 12
more then 5.5 volts, go to step 11

Step 10. Check connections in circuit 633, repair short to ground, retest to confirm

Step 11. Repair short to voltage in circuit 633, retest to confirm.

Step 12. Start engine, and observe voltmeter at idle

less then 2.0 volts, replace DIS module, retest to confirm
2.0 - 4.0 volts, problem intermittent
4.0 - 5.5 volts, go to step 13
more then 5.5 volts, go back up to step 11

Step 13. Turn ignition on, back probe circuit 633 at DIS module with voltmeter, other lead to ground and check voltage.

4.0 volts or less, repair open/high resistance in circuit 633, retest to confirm.
Greater than 4.0 volts, go to step 14

Step 14: Inspect terminal on DIS module for looseness or poor connection.

If terminal is bad, repair it.
If terminal is good, replace the DIS module.
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Friday, May 7th, 2010 AT 2:48 PM
Tiny
BENSJETS
  • MEMBER
  • 64 POSTS
  • 1999 SATURN SC2
  • 4 CYL
  • 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?
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Saturday, January 16th, 2021 AT 6:01 PM (Merged)
Tiny
SATURNTECH9
  • MECHANIC
  • 30,869 POSTS
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.
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Saturday, January 16th, 2021 AT 6:02 PM (Merged)
Tiny
BENSJETS
  • MEMBER
  • 64 POSTS
Louie, Is this you?I changed the plug wires which were two years old. The check engine light hasn't come on since (5days). Once again you know your stuff. Thanks so very much.
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Saturday, January 16th, 2021 AT 6:02 PM (Merged)
Tiny
SATURNTECH9
  • MECHANIC
  • 30,869 POSTS
Your welcome anytime you need help hit me up.
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Saturday, January 16th, 2021 AT 6:02 PM (Merged)

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