When l put my Lincoln in reverse it will not move(or less im on a hill). When l try to hit the gas to back up the engine rev out as if its in neutral. l know in my aunt car the gears and the dash not even so l tried moving the stick over some to see if it will then do it but it didn't. The service engine light comes on and goes off. The transmission fluid was low but l put more in it. Do you know what the problem is. Why its still not backing up

Your transmission is either out or in the process. You might want to check the Valve Body to make sure that it is tight.

Trans is going, Always keep a spare. Its at the vary back of the trans too, pain to fix. Get a rebuild kit and a manual.

You determine what transmission you have by looking at the sticker on the drivers door.
On the sticker look below the ''Tr'' or ''Trans'' for one of the following letters.
T = AOD
P = AODE
U = 4R70W or AODE-W

probably transmittion problem