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. The PCM runs the following 2 tests to diagnose the CMP sensor performance system:

    • A Near Engine Start, CMP Fast Event Based test
    • An After Engine Start, CMP Slow Event Based test

The Near Engine Start and the CMP Fast Event Based test runs first, upon or during, start-up. If the test fails, it will set DTC P0341. If the test passes, it will initiate the After Engine Start, CMP Slow Event Based test, and runs this test continuously. If the PCM detects an incorrect correlation between the CMP signal and the crankshaft position (CKP) signals, DTC P0341 will set.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0341 Camshaft Position (CMP) Sensor Performance

Conditions for Running the DTC

Near Engine Start, CMP Fast Event Based, Test

    • The engine is cranking.
    • DTC P0340 is not set.

After Engine Start, CMP Slow Event Based, Test

    • The engine is running.
    • DTCs P0335, P0340, P0385, and P1372 are not set.
    • DTC P0341 runs continuously once the above conditions are met.

Conditions for Setting the DTC

Near Engine Start, CMP Fast Event Based, Test

During cranking, the PCM detects an incorrect number of CMP sensor pulses in 2 revolutions of the crankshaft.

After Engine Start, CMP Slow Event Based, Test

The PCM detects an incorrect number of CMP sensor pulses in 2,000 revolutions of the crankshaft.

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

The following conditions may cause this DTC to set:

    • Damage to the camshaft sprocket
    • Incorrect sensor installation
    • The sensor coming in contact with the camshaft sprocket
    • Excessive air gap between the camshaft sprocket and the sensor
    • A cracked or damaged sensor
    • Foreign material passing between the sensor and the sprocket

If the condition is intermittent, refer to Intermittent Conditions .

Step

Action

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

Visually and physically inspect all circuits going to the camshaft position (CMP) sensor for the following:

    • Being routed too close to secondary ignition wires or components
    • Being routed too close to after-market add-on electrical equipment
    • Being routed too close to solenoids, relays, and motors

If you find incorrect routing, correct the harness routing.

Did you find and correct the condition?

Go to Step 9

Go to Step 3

3

Test for an intermittent and for a poor connection at the CMP sensor. 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 4

4

Test for an intermittent and for a poor connection at the powertrain control module (PCM). 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 5

5

  1. Remove the CMP sensor. Refer to Camshaft Position Sensor Replacement .
  2. Visually inspect the CMP sensor for the following conditions:
  3. • Physical damage
    • Excessive wear of the sensor
    • Loose or improper installation

Did you find and correct the condition?

Go to Step 9

Go to Step 6

6

Visually inspect the camshaft sprocket for damage.

If the camshaft sprocket is damaged, refer to Camshaft Timing Drive Components Cleaning and Inspection in Engine Mechanical.

Did you find and correct the condition?

Go to Step 9

Go to Step 7

7

Replace the CMP sensor. Refer to Camshaft Position Sensor Replacement .

Did you find and correct the condition?

Go to Step 9

Go to Step 8

8

Replace the PCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you find and correct the condition?

Go to Step 9

Go to Diagnostic Aids

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.

Did 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