GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The powertrain control module (PCM) uses the camshaft position (CMP) sensor high resolution signal in order to determine the position of the valve train in relation to the engine cylinders. The PCM uses the CMP high resolution signal in order to sequence the ignition system, and the fuel injectors.

The PCM supplies a 12-volt reference and a low reference to the CMP sensor. The CMP sensor returns a signal pulse in response to the reluctor track, located on the camshaft sprocket. If the PCM detects an incorrect correlation between the CMP signal and the crankshaft position (CKP) signals, diagnostic trouble code (DTC) P0341 will set.

Conditions for Running the DTC

The engine running less than 2,000 RPM.

Conditions for Setting the DTC

The PCM detects an incorrect correlation between the CMP signal and the CKP signals.

Action Taken When the DTC Sets

    â€¢ The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
    â€¢ The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

Conditions for Clearing the MIL/DTC

    â€¢ The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
    â€¢ A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
    â€¢ A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
    â€¢ Clear the MIL and the DTC with a scan tool.

Diagnostic Aids

If the condition is intermittent, refer to Intermittent Conditions .

DTC P0340 may set in addition to DTC P0341. If the calibrated number of cylinder events occur with a loss of CMP high resolution signal, DTC P0340 will set. An intermittent loss of signal or signal circuit noise, or poor connections at the PCM and CMP sensor will set DTC P0340 and P0341.

If the camshaft to crankshaft timing relationship is incorrect, DTC P0340 will not set. The PCM still receives the correct number CMP high resolution signal pulses. However, because the signal occurs at an incorrect correlation to the crankshaft signals, DTC P0341 will set.

Step

Action

Yes

No

Schematic Reference: Engine Controls Schematics

1

Did you perform the Diagnostic System Check-Engine Controls?

Go to Step 2

Go to Diagnostic System Check - Engine Controls

2

Is DTC P0340 also set?

Go to Step 3

Go to Step 7

3

  1. Test the CMP 12-volt reference circuit for the following conditions:
  2. • Intermittent open
    • Poor connections at the PCM and the CMP sensor
  3. If a condition is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 8

Go to Step 4

4

  1. Test the CMP high resolution signal circuit for the following conditions:
  2. • An intermittent open
    • An intermittent short to ground or CMP sensor low reference.
    • An intermittent short to the CMP 12-volt reference circuit
    • Poor connections at the PCM and the CMP sensor
  3. If a condition is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 8

Go to Step 5

5

  1. Test the CMP sensor low reference circuit for the following conditions:
  2. • An intermittent open
    • Poor connections at the PCM and the CMP sensor
  3. If a condition is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 8

Go to Step 6

6

  1. Test the CMP harness wiring for improper routing near high frequency devices.
  2. If a condition is found, correct as necessary.

Did you find and correct the condition?

Go to Step 8

Go to Intermittent Conditions

7

  1. Test the valve train for the following conditions:
  2. • Damaged or misaligned camshaft timing components
    • Proper camshaft timing, refer to Setting Camshaft Timing in Engine Mechanical 4.6L.
  3. If a condition is found, repair as necessary.

Did you find and correct the condition?

Go to Step 8

Go to Intermittent Conditions

8

  1. Use the scan tool in order to clear the DTCs.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the conditions for Running the DTC as specified in the supporting text.

Does the DTC run and pass?

Go to Step 9

Go to Step 2

9

With a scan tool, observe the stored information, Capture Info.

Does the scan tool display any DTCs that you have not diagnosed?

Go to Diagnostic Trouble Code (DTC) List

System OK