No Reverse Gear

WARNING: This page is about a different car, the 2010 GMC Sierra and 2010 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.

Checks	Causes
Drive Motor with Generator - Position 2	Motor Failure Inspect 3 phase cables. Inspect connections at motor. Inspect motor end bearings. NOTE: Should have DTC present.
Control Valve Upper Body Assembly	Inspect for worn, damaged, or sticking regulator valve and valve spring.
Control Valve Lower Body Assembly	Inspect for worn, damaged, or sticking clutch select solenoid valve 3 and valve spring.