GM Service Manual Online
For 1990-2009 cars only

Circuit Description

This ignition system does not use a conventional camshaft position (CMP) sensor that detects valve train position. The ignition control module (ICM) detects when #1 or #3 cylinder has fired on the compression stroke using sensing circuitry integrated within each coil. The sensing circuit detects the polarity and the strength of the secondary voltage output. The higher output is always at the event cylinder. The ICM sends a camshaft position signal to the powertrain control module (PCM) based on the voltage difference between the event and waste cylinder firing energy. This system is called compression sense ignition. By monitoring the camshaft position and crankshaft position signals the PCM can accurately time the operation of the fuel injectors. If the PCM receives an intermittent camshaft position signal from the ICM then DTC P0341 will set.

Conditions for Running the DTC

The engine is running.

Conditions for Setting the DTC

The PCM detects 8 failures out of the last 10 tests when manifold absolute pressure (MAP) is more than 45 kPa.

Action Taken When the DTC Sets

    • The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
    • 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

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

Diagnostic Aids

    • An intermittent fault in the crankshaft position (CKP) circuits may cause the PCM to resync the cam and may set this DTC.
    • An intermittent short to voltage on the camshaft position signal can set this DTC. A direct short to voltage on the camshaft position signal circuit will set DTC P0340, as there will be no change in the camshaft position signal input.
    • Electromagnetic interference (EMI) may also set DTC P0341. Inspect the wiring harness for the following:
       - Damage
       - Being routed too close to motors, solenoids, and relays
       - Being routed too close to secondary ignition wires or components
       - Being routed too close to aftermarket add-on electrical equipment

If this DTC is determined to be intermittent, refer to Intermittent Conditions .

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This step determines if DTC P0341 is the result of a hard malfunction or an intermittent condition.

  2. On a normal operating system, the duty cycle should stay within the specified range. If it does not stay within the specified range the ICM has encountered a problem.

  3. A faulty electrical connection in the camshaft position signal circuit can cause the CMP Resync Counter to increment. Anytime a faulty electrical connection is present, the CMP Reference Activity counter will stop incrementing.

Step

Action

Value

Yes

No

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views

1

Did you perform the Diagnostic System Check--Vehicle?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.

Are any other DTCs set?

--

Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information

Go to Step 3

3

  1. Observe the Freeze/Frame Failure Records for this DTC.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze/Frame Failure Records.

Did the DTC fail this ignition?

 

Go to Step 4

Go to Diagnostic Aids

4

  1. Turn OFF the ignition.
  2. Disconnect the ignition control module (ICM).
  3. Connect a jumper wire from each terminal, except the CMP signal circuit, in the ICM harness connector to the corresponding terminal at the ICM with the J 35616 Connector Test Adaptor Kit.
  4. Measure the Duty Cycle from the camshaft position signal circuit at the ICM and to a good ground with a DMM. Refer to Circuit Testing in Wiring Systems.
  5. Start the engine.

Does the Duty Cycle stay within the specified range?

47-52%

Go to Step 6

Go to Step 5

5

  1. Turn OFF the ignition.
  2. Test for an intermittent and for a poor connection at the ICM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

 

Go to Step 9

Go to Step 7

6

  1. Disconnect the powertrain control module (PCM).
  2. Test for an intermittent and for a poor connection of the camshaft position signal circuit at the PCM connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

 

Go to Step 9

Go to Step 8

7

Replace the ICM. Refer to Ignition Control Module Replacement .

Did you complete the replacement?

 

Go to Step 9

--

8

Replace the PCM. Refer to Powertrain Control Module Replacement .

Did you complete the replacement?

 

Go to Step 9

--

9

  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Does the DTC fail this ignition?

 

Go to Step 2

Go to Step 10

10

Observe the Capture Info with a scan tool.

Are there any DTCs that have not been diagnosed?

 

Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information

System OK