GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The camshaft position (CMP) actuator system enables the engine control module (ECM) to change the timing of the camshafts while the engine is running. The CMP actuator solenoid signal from the ECM is pulse width modulated (PWM). The ECM controls the CMP actuator solenoid duty cycle by controlling the amount of solenoid ON time. The CMP actuator solenoid controls the advance or the retard of each camshaft. The CMP actuator solenoid controls the oil flow that applies the pressure to advance or retard the camshafts.

Ignition voltage is supplied directly to the CMP actuator solenoid. The ECM controls the solenoid by grounding the control circuit with a solid state device called a driver. The driver is equipped with a feedback circuit that is pulled up to a voltage. The ECM can determine if a control circuit is open, shorted to ground, or shorted to a voltage by monitoring the feedback voltage. If the ECM detects the control circuit voltage is within a predetermined range when the circuit is commanded OFF, this DTC sets.

DTC Descriptors

This diagnostic procedure supports the following DTCs:

    • DTC P0010 Intake Camshaft Position (CMP) Actuator Solenoid Control Circuit (Bank 1)
    • DTC P0013 Exhaust Camshaft Position (CMP) Actuator Solenoid Control Circuit (Bank 1)
    • DTC P0020 Intake Camshaft Position (CMP) Actuator Solenoid Control Circuit (Bank 2)
    • DTC P0023 Exhaust Camshaft Position (CMP) Actuator Solenoid Control Circuit (Bank 2)

Conditions for Running the DTC

    • The engine speed is more than 80 RPM.
    • The ignition 1 voltage is between 10-19 volts.
    • The ECM has commanded the CMP actuator solenoid ON and OFF at least once during the ignition cycle.
    • DTCs P0010, P0013, P0020, and P0023 runs continuously once the above conditions are met.

Conditions for Setting the DTC

    • The ECM detects an open in the CMP actuator solenoid circuits when the solenoid is commanded OFF.
    • The condition exists for more than 4 seconds.

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 4 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

    • Use the J 35616-A/BT-8637 Connector Test Adapter Kit for any test that requires probing the ECM harness connector or a component harness connector.
    • The lower connector of the ECM is connector C1 and the upper connector of the ECM is connector C2. Refer to Front of Vehicle/Engine Compartment Component Views.
    • If the condition is intermittent, move the related harnesses and connectors, with the engine operating, while monitoring the circuit status for the component with a scan tool. The circuit status parameter changes from OK or Indeterminate to Fault if there is a condition with the circuit or a connection. The ODM information is in the output driver module (ODM) data list.
    • For an intermittent condition, refer to Intermittent Conditions.

Test Description

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

  1. This step determines if the condition exists. The engine speed must be increased to enable the CMP actuator solenoids. The DTC will not set unless the solenoid is commanded ON and OFF at least once during the ignition cycle.

  2. This step verifies that the ECM is providing a ground to the CMP actuator solenoid.

  3. This step determines if there is an internal condition with the ECM. The CMP actuator control circuit is pulled-up to a voltage within the ECM. The ECM uses this voltage as a feedback circuit. The ECM can determine if the control circuit is open, shorted to ground, or shorted to a voltage by monitoring the feedback voltage. If the voltage is not within the specified range, there is a condition with the ECM.

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Component Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  1. Start the engine.
  2. Allow the engine to reach operating temperature.
  3. Increase the engine speed to the specified value for 10 seconds.
  4. Observe the DTC information with a scan tool.

Did DTC P0010, P0013, P0020, or P0023 fail this ignition?

2,000 RPM

Go to Step 4

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 Intermittent Conditions

4

  1. Turn OFF the ignition.
  2. Disconnect the camshaft position (CMP) actuator solenoid. Refer to the appropriate procedure:
  3. Turn the ignition switch to ON position, with the engine OFF.
  4. Probe the ignition 1 voltage circuit of the CMP actuator solenoid with a test lamp that is connected to the engine control module (ECM) housing.

Does the test lamp illuminate?

--

Go to Step 5

Go to Step 10

5

  1. Connect a test lamp between the control circuit of the CMP actuator solenoid and the ignition 1 voltage circuit of the CMP actuator solenoid.
  2. Start the engine.
  3. Command the appropriate CMP actuator solenoid from 0 to 40 and back to 0 degrees with a scan tool.
  4. Exit the CMP Actuator Solenoid Control function.
  5. Note: The ignition must be turned OFF or the CMP actuator may not operate correctly after using the output control.

  6. Turn OFF the ignition.

Does the test lamp turn ON when commanded with a scan tool?

--

Go to Step 7

Go to Step 6

6

Test the control circuit of the CMP actuator solenoid for an open. Refer to Circuit Testing and Wiring Repairs.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 9

7

Measure the voltage from the control circuit of the CMP actuator solenoid to the ECM housing with a DMM. Refer to Circuit Testing.

Is the voltage within the specified range?

2.0-3.0 V

Go to Step 8

Go to Step 12

8

Test for an intermittent and for a poor connection at the CMP actuator solenoid. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 11

9

Test for an intermittent and for a poor connection at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 12

10

  1. Repair the ignition voltage circuit of the CMP actuator solenoid for an open or for an intermittent short to ground. Refer to Wiring Repairs.
  2. Replace the fuse if necessary.

Did you complete the repair?

--

Go to Step 13

--

11

Replace the CMP actuator solenoid. Refer to the appropriate procedure:

Did you complete the replacement?

--

Go to Step 13

--

12

Replace the ECM. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

--

Go to Step 13

--

13

  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 14

14

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

System OK