Variable Valve Lift Solenoid
There are four Variable Valve Lift (VVL) solenoids that control the operation of the Intake rocker arms for all six cylinders. See the figure and table below for the VVL Solenoid locations and cylinder control:
| VVL SOLENOID | PHYSICAL LOCATION | CYLINDERS CONTROLLED |
|---|---|---|
| VVL SOLENOID 1/1 | BANK 1 FRONT SOLENOID (1) | CYLINDER 1 INTAKE VALVES |
| VVL SOLENOID 1/2 | BANK 1 REAR SOLENOID (2) | CYLINDERS 3 AND 5 INTAKE VALVES |
| VVL SOLENOID 2/1 | BANK 2 FRONT SOLENOID (4) | CYLINDER 2 INTAKE VALVES |
| VVL SOLENOID 2/2 | BANK 2 REAR SOLENOID (3) | CYLINDERS 4 AND 6 INTAKE VALVES |
The Variable Valve Lift (VVL) system is designed to vary the lift and duration of the intake valves, to maximize efficiency and engine torque, depending on engine operation. The VVL system consists of 2 step intake rocker arms that are capable of operating in High Lift or Low Lift mode. The four VVL solenoids control the rocker arm modes using engine oil pressure.
- Low Lift Mode: The Powertrain Control Module (PCM) commands the VVL Solenoids on, which supplies 12.0 volts to the VVL solenoids and allows engine oil pressure to pass through the solenoids to the rocker arms. This in turn pushes the lock pins back which allows the center of the rocker arms to move down freely, allowing the rocker arms to operate in Low Lift Mode. It takes approximately 20.0 psi of engine oil pressure at the rocker arms to move the lock pins.
- High Lift Mode: The rocker arms default to High Lift mode when no oil pressure is present. This is accomplished with a spring loaded lock pin that keeps the center of the rocker arms in the High Lift position. The PCM commands the VVL Solenoids off when High Lift Mode is desired.
The PCM performs a diagnostic check on each VVL Solenoid High Side Driver Circuit for an open or short in the circuitry. If no circuit faults are detected, the PCM runs a rationality diagnostic to check for any rocker arms that are stuck in the High Lift or Low Lift positions. The PCM can determine this by monitoring for an erratic MAP Sensor signal along with the misfire, knock and Individual Cylinder Fuel Control (ICFC) monitors to detect a rocker arm that is stuck in an incorrect position for a given cylinder. This diagnostic can also detect the mechanical failure of a solenoid or an oil pressure issue to one or more of the rocker arms. When a fault is detected for a rocker arm, the PCM will begin to record in field data for diagnostic purposes until the PCM defaults the VVL system to High Lift or Low Lift mode. If the condition goes away during the drive cycle the data collected will also be cleared.
For VVL solenoid oil pressure testing, refer to VVL SOLENOID OIL PRESSURE TEST .