Circuit Description: Notes

The DTC P2646 Intake Rocker Arm Actuator System Stuck Off 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.

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 P2646 sets when the signal circuit of the rocker arm oil pressure switch remains low even when engine speed is more than 4,400 RPM. For additional information on the operation of the rocker arm oil control system, refer to Rocker Arm Oil Control System Description .