No Engine Braking in First Gear

WARNING: This page is about a different car, the 2005 Cadillac STS. However, it is still accessible from the selected car via links, so may be relevant.

Check	Causes
DEFINITION: A large engine RPM increase and forward vehicle speed decrease do not immediately occur when the transmission is shifted from Overdrive or fourth gear in Drive or manual third range to first.
Low and Reverse Clutch	Damaged or cut piston Damaged or worn clutch plates
Control Valve Body Accumulator Assembly	3-4 shift control valve stuck 3-4 shift valve stuck - 1st, 2nd or 3rd gear Low pressure control valve - 1st, 2nd or 3rd gears 4-5 SS valve stuck off - 1st, 2nd, or 3rd gears 4-5 shift valve stuck applied - 1st, 2nd, 3rd gears 3-4 shift valve and/or 3-4 control shift valve stuck released Low pressure control valve stuck released 4-5 shift valve and/or 4-5 control shift valve stuck released 1-2 shift valve stuck released