transmission automatically downshifting

[rn240sx]

Hey guys..I have a 92 pickup and i just realized something the other day. My normal commute to work is only 7 miles one way. The 3 main roads i take to work are only 40mph speed limit roads.. Thur there was a major accident on one of the roads so i bypass'd that road and took the local expressway. While i was steadily increasing speed i noticed that when i got to 45mph, the transmission automatically downshifted to 3rd gear.... i was like, what the heck...?? So i slowed down to about 35mph and the transmission went back into 4th gear like normal. Then i hit the gas pedal to slightly accelerate and again, at 45 mph, the truck downshifted again back to 3rd and rpm's went up...Keep in mind, i just purchased this truck a few months ago and i never use the hwy for anything and the roads i take are 40mph and under so i never noticed this problem...I checked the transmission fluids and they are fine and red in color. Any reason as to why its down shifting by itself to 3rd gear at 45mph... is this an ecu issue or transmission issue..??

[marlin29311]

Try unplugging the battery so the system can reset itself. The previous owner may have driven in such a weird way that the car was accustomed to driving that way, and by unplugging the battery for a while, hopefully the AT memory will clear, and it will re-learn shift points.

[rn240sx]

The previous owner may have driven in such a weird way that the car was accustomed to driving that way, and by unplugging the battery for a while, hopefully the AT memory will clear, and it will re-learn shift points.

i didnt think that was even possible, but i will try, thanx