GM Service Manual Online
For 1990-2009 cars only

Object Number: 564000  Size: SF
Engine Controls Component Views
Power, Ground, CMP, KS, and CKP
OBD II Symbol Description Notice
Powertrain Control Module Connector End Views
Handling ESD Sensitive Parts Notice

Circuit Description

The camshaft position (CMP) sensor correlates the crankshaft to camshaft position so that the Powertrain Control Module (PCM) can determine which cylinder is ready to be fueled by the injector. The CMP sensor also determines which cylinder is misfiring when a misfire is present. If the PCM receives an intermittent signal from the CMP, then the CMP Resync Counter will increment. When the PCM cannot use the information from the CMP sensor, a DTC is set and the PCM will fuel the engine by using the alternating synchronous double fire (ASDF) method.

Conditions for Running the DTC

The engine is running.

Conditions for Setting the DTC

The PCM sees more than 15 CMP sensor resyncs in 256 seconds (4 min., 16 sec.).

Action Taken When the DTC Sets

    • The malfunction indicator lamp (MIL) will illuminate after two consecutive ignition cycles in which the diagnostic runs with the fault active.
    • The PCM records the operating conditions at the time when the diagnostic fails. This information stores in the Freeze Frame and Failure Records buffers.
    • A history DTC stores.
    • The coolant fan turns ON.

Conditions for Clearing the MIL/DTC

    • The MIL will turn OFF after three consecutive ignition cycles in which the diagnostic runs without a fault.
    • A history DTC will clear after 40 consecutive warm-up cycles without a fault.
    • Use a scan tool to clear the DTCs.

Diagnostic Aids

    • An Intermittent problem may be caused by the following conditions:
       - A faulty electrical connection
       - Rubbed-through wire insulation
       - A broken wire inside the insulation
    • Inspect any suspected circuitry for the following conditions:
       - Backed-out terminals
       - Improper mating
       - Broken locks
       - Improperly formed or damaged terminals
       - Faulty terminal-to-wiring connections
       - Physical damage to the wiring harness.
    • If the PCM sees less than 15 resyncs in 256 seconds, the counter is reset to 0. Any time a faulty electrical connection is present, the CMP Reference Activity counter will stop incrementing and the CMP Resync Counter will increment.

Test Description

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

  1. The Powertrain On-Board Diagnostic (OBD) System Check prompts you to complete some of the basic diagnostics and to store the Freeze Frame and Failure Records data on the scan tool, if applicable. This creates an electronic copy of the data that was captured when the malfunction occurred. The scan tool stores this data for later reference.

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

  3. The counter should stop incrementing with the sensor electrical connector disconnected and set a DTC P0340. If the counter stills increments, this indicates that the PCM is malfunctioning.

  4. By moving the CMP sensor electrical connector, the connections at the sensor are being checked. Make sure that the electrical connector remains securely fastened.

  5. A faulty electrical connection in any of the circuits at the CMP sensor will cause the CMP Resync Counter to increment. Any time a faulty electrical connection is present, the CMP Reference Activity counter will stop incrementing and the CMP Resync Counter will increment.

  6. Reprogram the replacement PCM and perform the crankshaft position system variation procedure. Refer to the latest Techline™ procedures for PCM reprogramming.

DTC P0341 - Camshaft Position (CMP) Sensor Circuit Performance

Step

Action

Value(s)

Yes

No

1

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

  1. Turn ON the ignition, with the engine OFF.
  2. Install a scan tool.
  3. Check if DTC P0336 is set.

Is DTC P0336 set?

--

Go to DTC P0336 Crankshaft Position (CKP) Sensor Performance

Go to Step 3

3

  1. Start the engine.
  2. Allow the engine to idle.
  3. Observe the CMP Resync Counter with the scan tool.

Is the CMP Resync Counter incrementing?

--

Go to Step 4

Go to Step 5

4

Caution: Avoid contact with moving parts and hot surfaces while working around a running engine in order to prevent physical injury.

  1. Turn OFF the ignition.
  2. Disconnect the CMP sensor electrical connector.
  3. Start the engine.
  4. Observe CMP Resync on the scan tool.

Did the CMP Resync Counter stop incrementing?

--

Go to Step 6

Go to Step 7

5

Caution: Avoid contact with moving parts and hot surfaces while working around a running engine in order to prevent physical injury.

Wiggle the CMP sensor electrical connector by hand while the engine is still running.

Did the CMP Resync Counter start to increment?

--

Go to Step 6

Go to Step 10

6

  1. Turn OFF the ignition.
  2. Check for a faulty electrical connection at the CMP sensor electrical connector.
  3. Repair the electrical connector as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a repair necessary?

--

Go to Step 11

Go to Step 8

7

Important: Refer to Powertrain Control Module Replacement/Programming .

Replace the PCM. Refer to Powertrain Control Module Replacement .

Did you complete the replacement?

--

Go to Step 11

--

8

  1. Disconnect the PCM electrical connector.
  2. Check the CMP terminals for a faulty electrical connection.
  3. Repair the terminals as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a repair necessary?

--

Go to Step 11

Go to Step 9

9

Replace the camshaft position (CMP) sensor. Refer to the Camshaft Position Sensor Replacement .

Is the action complete?

--

Go to Step 11

--

10

  1. Review the Freeze Frame data and verify the parameters.
  2. Operate the vehicle within the Freeze Frame conditions and Conditions for Setting the DTC as specified.

Is the CMP Resync Counter incrementing?

--

Go to Step 4

Go to Step 11

11

  1. Clear the DTCs with the scan tool.
  2. Start the engine.
  3. Idle the engine at the normal operating temperature.
  4. Operate the vehicle within the Conditions for Setting the DTC as specified in the supporting text.

Does the scan tool indicate that this diagnostic ran and passed?

--

Go to Step 12

Go to Step 2

12

Check to see if any additional DTCs are set.

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

--

Go to Diagnostic Trouble Code (DTC) List/Type

System OK