Hi guys, I have a 2002 Bonneville ssei with about 78k miles now. I am having an issue with the transmission that I can't figure out. The problem is a harsh shift only in the 3-2 downshift, it won't do it everytime but the easiest way to get it to happen is when going up a hill or making a turn, then push gas slightly it will jerk very quickly into 2nd gear but the shift itself seems fine-no slipping, surging, hesitation etc.
it will also happen from gears 1-2 if I give it lots of gas as soon as it shifts into 2nd it will do the same jerk. Shifting manually into 2nd it will do the same thing only at about 1000-1500 rpms. (Will not happen at High rpms) I can only assume these symptoms are related to each other because they all happen at light throttle. Under normal acceleration and coasting all seems to be fine. I've recently replaced front transmission mount, spark plugs/wires. There are no codes except ABS codes and an occasional check engine light for O2 sensor. To my knowledge the transmission has not been serviced but fluid is fine. Does anyone have any clues what to try? I can live with it, I just don't want to harm transmission.