help, tranny problem

hello, i'm new here. I have a 1992 bonneville se with right around 300k on it.
just about 2 weeks ago i noticed the tranny wasn't shifting right. so i checked the fluid. was a little low, so i bought a quart and put in it. i bout an extra one to keep in the car. Never seen a leak, and was wondering why it was low. i stared to drive and it never shifted up into overdrive. i stopped and put another quart in it. it still never shifted (without checking leverl of fluid) i proceeded abou 15 miles to nearest gas station and bought 2 more quarts and checked, was above the mark, i noticed a leak. pretty steady leak in a line. i didnt have anything to fix it with and all parts stores etc were closed. i proceeded to my destination about 45 mins away. about another 15 miles, it did not shift until i stiopped. I bought 2 more quarts to keep on hand just in case. when i left there it shifted for the next 30 miles. after that it stopped i stopped at my destinatio point. got to looking around and playing and jiggling wires etc to see what could possibly be wrong. when i made a right turn onto the main highway on my way back home it hit hard and downsihfted to first and then proceeded to shift into overdrive. and stayed that way all the way home. Heading to work the next morning, no shift into first or overdrive ( i did stop at parts store and get a piece of rubber hose and clamps to stop the leak). Since then it has not but intermittently shifted into first or overdrive. i replaced the modulator valve because i noticed it was bad, ( i could shake it and the pin in the middle moved,) i have chked wiring etc. i'm at a loss.. why all of sudden beccase of a leak.... i'm thinking electrical, but not sure where to start.. i thought it might be the wiring that i moved and jiggled the night before, but that didn't do any good. . Any ideas. transmission guy look at it and said his computer only showed transmission shift problem. i think he said code 36 ( not for sure tho).

Welcome to AF. A full trans scan will allow someone to command up shifts, at that mileage anything is possible there is no quick answer or magic bullet here. a road test and basic checks done by a trans specialist is the only way. If the test done showed a shift problem that that is the avenue to pursue with addt'l diagnostics.

well, thanks for the reply.. i;m pretty sure i have it fixed now.. i noticed that everytime it didn't shift into overdrive or first, the cruse wouldn't work, but when it did shift , the cruse worked...........get this one.. what makes the cruise shut off ( the brake ) , solution of what i did., ( tap on the brake pedal switch ) an all works fine so far.. will try again tomorrow and see what happens......never would have thought about that, if i hadn't have started back at square 1. I noticed that when i applied the brake and came to a stop, sometimes it would work and shift down to first on takeoff and finally upshift all the way to overdrive,, but then sometimes it wouldn't.. still confused a little about the whole system and why or how, but anyway it works....but again, thanks for the reply..