Vane Position Control Solenoid: Operated by the ECM, it controls the variable geometry function of the turbocharger. This is accomplished by altering the pressure and direction of engine oil ...

It could be either a vane-position sensor has failed or the vanes and actuator inside the turbo are gunked up with carbon deposits, unburned oil, and rust (probably on the unison ring they ride on).

The Variable Vane Brake (VVB) works with the turbocharger design used in the 2004.5-up Duramax engines to reduce turbo lag and increase power can now be tapped to slow your 2500/3500 HD down. BD ...