Diagnostic Instructions

DTC Descriptors

DTC P0026: Intake Valve Control Solenoid Control Performance

DTC P0027: Exhaust Valve Control Solenoid Control Performance

DTC P0076: Intake Valve Control Solenoid Control Circuit Low Voltage

DTC P0077: Intake Valve Control Solenoid Control Circuit High Voltage

DTC P0079:  Exhaust Valve Control Solenoid Control Circuit Low Voltage

DTC P0080:  Exhaust Valve Control Solenoid Control Circuit High Voltage

Circuit/System Description

The camshaft position (CMP) actuator system enables the engine control module (ECM) to change the timing of the camshafts while the engine is operating. 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 the control circuit is open, shorted to ground, or shorted to a voltage by monitoring the feedback voltage.

Conditions for Running the DTC

Conditions for Setting the DTC

P0026

The ECM detects actual intake CMP is greater than 50 degrees or less than 5 degrees when the difference between actual and desired CMP is greater than 20 degrees.

P0027

The ECM detects actual exhaust CMP is less than -50 degrees or greater than -5 degrees when the difference between actual and desired CMP is greater than 20 degrees.

P0076 or P0079

The ECM detects an open or short to ground in the CMP actuator solenoid circuits.

P0077 or P0080

The ECM detects a short to voltage in the CMP actuator solenoid circuits.

Action Taken When the DTC Sets

DTCs P0026, P0027, P0076, P0077, P0079, and P0080 are type B DTCs.

Conditions for Clearing the DTC

DTCs P0026, P0027, P0076, P0077, P0079, and P0080 are type B DTCs.

Diagnostic Aids

If the condition is intermittent, move the related harnesses and connectors, with the engine operating, while monitoring the scan too circuit status parameters for the component. The circuit status parameters change from OK or Not Run to Fault if there is a condition with the circuit or a connection.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Camshaft Actuator System Description

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. With the engine at normal operating temperature, raise the engine speed to 2,000 RPM for 10 seconds. DTCs P0026, P0027, P0076, P0077, P0079, or P0080 should not set.
2. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the appropriate camshaft position (CMP) actuator solenoid.
2. Ignition ON, verify that a test lamp illuminates between the ignition 1 voltage circuit terminal 1 and ground.

⇒

If the test lamp does not illuminate, test the ignition 1 voltage circuit for a short to ground or an open/high resistance. If the ignition 1 voltage circuit tests normal and the ignition 1 voltage circuit fuse is open, test all the components connected to the ignition 1 voltage circuit and replace as necessary.

3. Connect a test lamp between the control circuit terminal 2 and the ignition 1 voltage circuit terminal 1.
4. Command the CMP actuator solenoid ON and OFF with a scan tool. The test lamp should turn ON and OFF with each command?

⇒	If the test lamp does not turn ON and OFF, test the control circuit for a short to ground, a short to voltage, or an open/high resistance. If the circuit tests normal, replace the ECM.

5. If all circuits test normal, test or replace the CMP actuator solenoid.

Component Testing

1. Ignition OFF, disconnect the harness connector at the appropriate camshaft position (CMP) actuator solenoid.
2. Test for 7-12 ohms between the terminals of the CMP actuator solenoid.

⇒	If not within the specified range, replace the CMP actuator solenoid.

3. Test for OL ohms between each terminal of the CMP actuator solenoid and the CMP actuator solenoid housing.

⇒	If less than the specified value, replace the CMP actuator solenoid valve.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for engine control module replacement, setup, and programming