P2647

DTC P2647

CIRCUIT DESCRIPTION




The DTC P2647 Intake Rocker Arm Actuator System Stuck On diagnostic monitors the operation of the rocker arm oil control solenoid. The rocker arm oil control solenoid enables the powertrain control module (PCM) to operate the high speed cam system. The high speed cam system significantly increases valve lift at engine speeds above 4,400 RPM. A second camshaft lobe with a high lift profile is cast into each camshaft, alongside the low/medium speed lobes. Unique rocker arms follow both the high speed and low/medium speed cam lobes. At engine speeds below 4,400 RPM, the low/medium speed cam lobes operate the rocker arms. When the rocker arm oil control solenoid is turned ON between 4,400-6,500 RPM, the rocker arms are operated by the high speed cam lobes. The rocker arm oil control solenoid is energized by a 12-volt signal from the PCM.

Rock Arm Actuator System Operation:

The rocker arm oil pressure switch detects oil pressure when oil is flowing through the rocker arm oil supply system. When the rocker arm oil control solenoid is ON, the oil pressure switch opens and the signal circuit to the PCM remains high. A DTC P2647 sets when the signal circuit of the rocker arm oil pressure switch is high when engine speed is less than 4,200 RPM. For additional information on the operation of the rocker arm oil control system refer to Rocker Arm Oil Control System Description.

DTC DESCRIPTOR
This diagnostic procedure supports the following DTC:
DTC P2647 Intake Rocker Arm Actuator System Stuck On

CONDITIONS FOR RUNNING THE DTC
- Battery voltage is at least 10.5 volts
- The engine coolant temperature (ECT) is at least 10°C (50°F).
- Engine speed is less than 4,200 RPM.
- The transmission is not in Park or Neutral.
- DTC P2647 runs every time the enable criteria is met and the rocker arm oil control system is active.

CONDITIONS FOR SETTING THE DTC
- The signal circuit of the rocker arm oil pressure switch stays high.
- The above condition is present for at least 5 seconds.

ACTION TAKEN WHEN THE DTC SETS
- The PCM illuminates the malfunction indicator lamp (MIL).
- 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.

TEST DESCRIPTION

Steps 1-9:

Steps 10-16:

The numbers below refer to the step numbers on the diagnostic table.
1. The Diagnostic System Check - Vehicle 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 whether the condition that caused the DTC to set still exists.
4. The rocker arm oil pressure switch is closed when oil pressure is less than 49 kPa (7 psi).
8. This step tests for a stuck on rocker arm oil control solenoid.
14. After replacing the PCM, a new minimum throttle position and idle speed must also be established.