Transmission

[Monte Cooper]

I have a 2007 Sport Trac that will not shift into overdrive. NO engine service light on. At 55 mph runs at 2500 rpm. is this the computer, tranny solenoid ,or worse in tranny?

 

[FLOffroad]

There is a button on the shifter that can turn OD off, so I'd tap that first (making sure OD is activated/allowed).
Also, I think my truck is in 4th at 55mph too. Usually takes to about 60 to get into 5th (OD).

If there is something wrong, I'd guess computer or solenoid first.

 

[10uhcST]

If your OD is turned off, then you would have a yellow OD light lit up on the dash beside the tach.