Turbocharger Vane Position Sensor
WARNING: This page is about a different car, the 2008 GMC Sierra, 2008 GMC Cab & Chassis Sierra, 2008 Chevrolet Silverado, and 2008 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
The ECM uses the turbocharger vane position sensor to monitor the TC vane angle. The voltage is low when the TC vanes are open, and high when the TC vanes are closed.