Conditions for Setting the DTC: P0852
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 detects the Park/Neutral switch signal equals 12 volts (High) when the IMS reports a Park/Neutral range for 3 seconds.