Replace 2013 Buick Regal automatic shift knob

SOURCE: transmission sometimes shifts hard into next gear.

Typiclly this is caused by a failing Pressure Control Solenoid. Now in some cases, since you are in the 1996 model year you may have a vacuum modulator that controls the shift firmness that can be replaced as it is externally mounted. I dont know how best to describe what it looks like, but look down on your transmission, on the front side facing the radiator and if you see a canister like device that has a vacuum line running to it, that is the vacuum modulator and you could start by replacing that and see if it helps.

If you do not have the vacuum modulator and have instead the electronically controlled version of your transmission then you will have a Pressure Control Solenoid and it, unfortunately, is located on the inside of the transmission and cannot be easily replaced without dropping the whole transmission.

The pressure control solenoid is a common issue with your transmission (4T65) and Im leaning more towards you have the electronically controlled version (4T65E).

SOURCE: 2004 Buick Regal. Hard tranny shifts.

Try some Lucas Transmission fix. that stuff has done wonders for almost all of my tranny problems

SOURCE: 93 buick regal will not unlock when shifted into park

Your vehicle is designed to auto lock the doors when you reach about 15 mph. This is a one way deal. When you park the car, unlocking the doors becomes a manual process to insure the occupants safety at their destination.

SOURCE: 1994 Buick Regal 3.8L automatic overdrive.

Check the electrical connector above the modulator. If the connections are loose or the connector is damaged... similar things happened to mine.

SOURCE: replacing power steering pump in a 95 buick regal

i think you need to remove pully first it is a special puller gm has