Condition 1:

WARNING: This page is about a different car, the 2009 GMC Sierra, 2009 GMC Cab & Chassis Sierra, 2009 Chevrolet Silverado, and 2009 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

At start-up, all pressure switches do not indicate pressure.
Engine speed is greater than 500 RPM for 6 seconds or 400 RPM for 15 seconds.
Forward or REVERSE range is selected.