GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The DTC P0011 Intake Camshaft Position (CMP) System Performance-Retarded monitors the operation of the camshaft position (CMP) actuator system. The CMP actuator system enables the powertrain control module (PCM) to change the intake camshaft timing while the engine is running. The CMP actuator solenoid controls the advance or retard of the camshaft. The CMP actuator solenoid is controlled by a pulse width modulated (PWM) signal from the PCM. The CMP sensor monitors the camshaft position or the camshaft angle, and compares that position or phase to the crankshaft position (CKP) sensor signal. The PCM determines whether the camshaft angle is correct by comparing the actual camshaft position to the target camshaft position. By continuously analyzing the input of the CMP sensor and the CKP sensor the PCM can detect a failure in the CMP actuator system. For additional information on the operation of the CMP actuator system refer to Camshaft Actuator System Description .

DTC Descriptors

This diagnostic procedure supports the following DTC.

DTC P0011 Intake Camshaft Position (CMP) System Performance-Retarded

Conditions for Running the DTC

    • Battery voltage is at least 11 volts.
    • The engine is running between 600-4,000 RPM.
    • The engine coolant temperature (ECT) is between 75-100°C (167-212°F).
    • The vehicle is operating at more than 8 km/h (5 mph).
    • DTC P0011 runs once per drive cycle when the above conditions are met.

Conditions for Setting the DTC

    • The PCM detects an unexpected deviation in the relationship of the input signals of the CMP sensor and the CKP sensor.
    • The fault is present several times when the CMP actuator solenoid is activated.

Action Taken When the DTC Sets

    • The PCM illuminates the malfunction indicator lamp (MIL) after 2 consecutive ignition cycles in which the diagnostic runs with the fault active.
    • The PCM stores the conditions that were present when the DTC set as Freeze Frame data.

Conditions for Clearing the MIL/DTC

    • The PCM turns OFF the MIL on the third consecutive trip cycle during which the diagnostic has been run and the fault condition is no longer present.
    • A DTC clears after 40 consecutive warm-up cycles have occurred without a fault.
    • A DTC can be cleared by using the scan tool Clear DTC Information function.

Diagnostic Aids

Inspect for any recent engine mechanical repairs. An incorrectly timed or incorrectly installed camshaft can cause a DTC P0011 to set.

If a DTC P0012 and P0011 are both present, inspect for a malfunctioning CMP solenoid valve. Observe that the Cam Phase Angle and Cam Phase Angle Desired parameters on a scan tool are approximately equal. A difference in the two parameters indicates that the CMP solenoid may be sticking.

An intermittent malfunction may be caused by a fault in the electrical circuit of the CMP actuator valve. Inspect the wiring harness and components for an intermittent condition. Refer to Intermittent Conditions .

The information included in the Freeze Frame data can be useful in determining the vehicle operating conditions when the DTC first set.

Test Description

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

  1. The Diagnostic System Check-Engine Controls prompts the technician to complete some basic checks and store the Freeze Frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.

  2. This step checks the operation of the CMP actuator system. When commanded ON, the CMP actuator solenoid advances the camshaft, usually causing the engine to stall.

  3. This step visually inspects the operation of the CMP actuator solenoid valve. The solenoid plunger and spool valve movement should be smooth and rapid from extended to retracted.

Step

Action

Values

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-Engine Controls?

--

Go to Step 2

Go to Diagnostic System Check - Engine Controls

2

Is there a DTC P0010 or P0012 present?

--

Go to DTC P0010 or DTC P0012

Go to Step 3

3

  1. Start the engine.
  2. Allow the engine to reach normal operating temperature.
  3. Command the CMP actuator solenoid ON with the scan tool. Refer to Scan Tool Output Controls .

Does the engine idle very rough or stall when the CMP actuator solenoid is commanded ON with the scan tool?

--

Go to Diagnostic Aids

Go to Step 4

4

  1. Turn OFF the ignition.
  2. Remove the CMP actuator solenoid. Refer to Camshaft Position Actuator Solenoid Valve Replacement .
  3. Connect the CMP actuator solenoid to B+ and to ground with a pair of fused jumper wires.
  4. Observe the movement of the solenoid plunger when electrical power is applied and released.

Does the solenoid plunger extend to at least the specified value when voltage is applied and then retract when voltage is removed?

3 mm (0.125 in)

Go to Step 5

Go to Step 6

5

  1. Inspect the engine for the following engine mechanical concerns:
  2. • A damaged or misaligned CMP sensor reluctor
    • A worn timing chain and jumped timing
    • A damaged CMP sensor reluctor wheel.
    • An incorrectly installed or incorrectly timed camshaft
    • Low oil pressure or oil supply to the CMP actuator assembly or actuator solenoid
  3. Repair as necessary. Refer to Diagnostic Starting Point - Engine Mechanical in Engine Mechanical.

Was a repair necessary?

--

Go to Step 8

Go to Step 7

6

Replace the CMP actuator solenoid valve. Refer to Camshaft Position Actuator Solenoid Valve Replacement .

Is the action complete?

--

Go to Step 8

--

7

Replace the PCM. Refer to Powertrain Control Module Replacement .

Is the action complete?

--

Go to Step 8

--

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