Ford Ranger Overdrive Message

you can feel WHAT in the cab ?

Its an automatic transmission .

I can feel the gear shifting .

Is it manual or automatic.

is the new engine a larger capacity than the old one ie is it more powerfull ?

If the overdrive off light starts to blink, it would seem the engine computer may have detected a sensor reading that is out of range. That may be causing the overdrive to be released.

Do you see any gauge readings that are not normal? Are you getting the "check engine" light on? Have you tried switching the overdrive on and off to see if that clears it up?

First plug in to OBD port and check transmission codes. Also note if the problem occurs when it is warmer rather than cooler. The firm shift may be a default protective mode the transmission enters to reduce over heat. If the codes indicate a sensor problem try replacing the sensor. If replacing the sensor does not fix then replace the transmission control module. Note the ECM & TCM may be a combined unit. Just went through this, I had a strong feeling my problem was electronic but was beaten down by a dealer and a transmission shop that the tranny needed to be rebuilt. Rebuild only made the shifts firmer when in the protective mode. Now replacing the ECM/TCM ($100.00 salvage w/ 90 day warranty) should have started there. I had to use salvage as new or rebuilt is unavailable.