No Reverse Gear

WARNING: This page is about a different car, the 2008 Cadillac CTS. However, it is still accessible from the selected car via links, so may be relevant.

Checks	Causes
Control Valve Upper Body Assembly (304)	Inspect for worn, damaged, or sticking 3-5 reverse regulator valve (336) and valve spring (326). Inspect for damaged or missing #5 checkball.
Control Valve Lower Body Assembly (307)	Inspect for worn, damaged, or sticking clutch select solenoid valve 3 (352) and valve spring (353).