Silverado 1500 2WD V8-6.0L Hybrid (2009)
Variable Valve Timing Actuator: Description and Operation
Camshaft Actuator System Description
Camshaft Position (CMP) Actuator System
The camshaft position (CMP) actuator system is used for a variety of engine performance enhancements. These enhancements include lower emission
output through exhaust gas recirculation (EGR) control, a wider engine torque range, improved gas mileage, and improved engine idle stability. The
CMP actuator system accomplishes this by controlling the amount of intake and exhaust valve overlap. For the 6.0 liter (LFA) engine, the park position
for the CMP actuator and camshaft is 14.5 degrees after top dead center (ATDC), or 29 crankshaft degrees ATDC. The engine control module (ECM)
can only command the CMP actuator to advance the valve timing from the park position, or retard the valve timing back to the park position. The total
range of valve timing authority is 23 degrees camshaft rotation, or 46 degrees of crankshaft rotation. The control range is from the park position of 14.5
degrees camshaft, or 29 degrees crankshaft ATDC, to 8.5 degrees camshaft or 17 degrees crankshaft before top dead center (BTDC).
CMP Actuator System Operation
The camshaft position (CMP) actuator system is controlled by the control module. The control module sends a pulse width modulated 12-volt signal to a
CMP actuator solenoid in order to control the amount of engine oil flow to a camshaft actuator passage. There are 2 different passages for oil to flow
through, a passage for CAM advance and a passage for CAM retard. The camshaft actuator is attached to the front of the camshaft, and is hydraulically
operated in order to change the angle of the camshaft relative to crankshaft position (CKP). Engine oil pressure (EOP), viscosity, temperature, engine oil
level, and aftermarket engine oil additives can have an adverse affect on camshaft phaser performance.
CMP Actuator Solenoid Circuit Diagnostic
The engine control module (ECM) monitors the control circuit of the camshaft position (CMP) actuator solenoid for electrical faults. The control module
has the ability to determine if a control circuit is open, shorted high, or shorted low. If the control module detects a fault with the CMP actuator solenoid
control, DTC P0010 will set.
