Circuit Description
| • | The cam phasing system is a hydraulically actuated phase shifting mechanism. The powertrain control module (PCM) supplies the ignition positive driver and ground circuits. A pulse width modulated (PWM) driver controls the amount that the camshaft actuator solenoid assembly advances or retards the exhaust camshaft. The exhaust camshaft is commanded to a maximum retard position of 25 degrees. When the exhaust camshaft is retarded at the maximum rate, the duty cycle of the signal is at 100 percent. The maximum advance rate has a 0 percent duty cycle. Other than when the camshaft is at full advance, a 50 percent duty cycle is used to maintain a steady retard angle. |
| • | This diagnostic trouble code (DTC) sets when the Desired and Actual Cam Phase angle error exceeds its tolerance value for a time period. |
Conditions for Running the DTC
| • | The engine is running. |
| • | The PCM has enabled the cam phaser. |
Conditions for Setting the DTC
| • | The vehicle must be driven. |
| • | The difference between the desired CAM phase angle and the actual CAM phase angle is more than 1.5 degrees. |
| • | The CAM phaser is steady for 20 seconds. |
| • | The condition is present for 20 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. |
The PCM disables the Cam phaser for the ignition cycle.
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 scan tool cam phase control function increments the cam phaser in 10 percent increments. Each increment equates to 2.5 degrees of cam phasing. A cam phase angle of 15 degrees is achieved by commanding the phaser with the scan tool to 60 percent. |
| • | Inspect any engine mechanical work that has been performed recently. Verify that the engine timing has not been altered. |
| • | If this DTC is set along with any crankshaft position (CKP) or camshaft position (CMP) sensor DTCs, then both the CKP and CMP sensor DTCs should be diagnosed prior to performing this diagnostic. The PCM uses both inputs to determine the actual camshaft position. |
| • | Check the following items: |
| • | A loose CMP sensor causing a variance in the sensor signal |
| • | A loose CKP sensor causing a variance in the sensor signal |
| • | Excessive free play in the timing chain and gear assembly |
| • | Debris or contamination interfering with the camshaft position actuator solenoid valve assembly |
| • | Debris or contamination interfering with the camshaft position actuator assembly |
| • | Engine oil has a major impact upon the camshaft actuation system's responsiveness. Oil temperature, viscosity, and quality can slow and/or inhibit the phaser's ability to reach a desired phase angle. |
| • | An intermittent may be caused by any of the following conditions: |
| • | A poor connection |
| • | Rubbed through wire insulation |
| • | A broken wire inside the insulation |
| • | Thoroughly check any circuitry that is suspected of causing the intermittent complaint. Repair the circuits as necessary. |
Step | Action | Values | Yes | No | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||||||||||||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |||||||||||||
2 |
Does the Cam Phase Angle Actual remain close to the Cam Phase Angle Desired at all commanded positions? | -- | Go to Step 3 | Go to Step 4 | ||||||||||||
3 |
Does the DTC fail this ignition? | -- | Go to Step 4 | Go to Diagnostic Aids | ||||||||||||
4 | Let the engine idle. Does the engine run rough or stall? | -- | Go to Step 9 | Go to Step 5 | ||||||||||||
5 |
Is the engine oil level within operating range? | -- | Go to Step 6 | Go to Fluid and Lubricant Recommendations in Maintenance and Lubrication | ||||||||||||
6 |
Does the oil pressure gage indicate engine oil pressure less than the specified value? | 28 psi (193 kPa) | Go to Oil Pressure Diagnosis and Testing in Engine Mechanical | Go to Step 7 | ||||||||||||
7 |
Does the Cam Phase Angle Actual increment at all? | -- | Go to Step 8 | Go to Step 10 | ||||||||||||
8 |
Does the resistance measure within the specified value? | 8-12 ohms | Go to Step 13 | Go to Step 19 | ||||||||||||
9 |
Caution: Avoid contact with moving parts and hot surfaces while working around a running engine in order to prevent physical injury. Does the test lamp turn ON and OFF? | -- | Go to Step 10 | Go to Step 15 | ||||||||||||
10 |
Did you find a problem? | -- | Go to Step 19 | Go to Step 11 | ||||||||||||
11 |
Does the spool valve move from fully closed to fully opened? | -- | Go to Step 12 | Go to Step 16 | ||||||||||||
12 | Inspect for the following conditions:
Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 13 | ||||||||||||
13 |
Does the resistance measure more than the specified value? | 5 ohms | Go to Step 18 | Go to Step 14 | ||||||||||||
14 | Measure the resistance on the low reference circuit with a DMM. Refer to Circuit Testing in Wiring Systems. Does the resistance measure more than the specified value? | 5 ohms | Go to Step 18 | |||||||||||||
15 | Test the camshaft position actuator high control circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 17 | ||||||||||||
16 | Inspect for poor connections at the harness connector of the camshaft position actuator solenoid valve assembly. Refer to Testing for Intermittent Conditions and Poor Connections and Repairing Connector Terminals in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 19 | ||||||||||||
17 | Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Repairing Connector Terminals in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 20 | ||||||||||||
18 | Repair the circuit. Refer to Wiring Repairs in Wiring Systems. Did you repair the circuit? | -- | Go to Step 21 | -- | ||||||||||||
19 | Replace the camshaft position actuator solenoid. Refer to Camshaft Position Actuator Solenoid Valve Replacement . Did you complete the replacement? | -- | Go to Step 21 | -- | ||||||||||||
20 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 21 | -- | ||||||||||||
21 |
Does the DTC run and pass? | -- | Go to Step 22 | Go to Step 2 | ||||||||||||
22 | Observe the stored information, Capture Info with a scan tool. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |||||||||||||
