Hi, 97 ford expo overdrive off light is flashing and i notice when it does the transmission knocks a little harder than ,normal any suggestions ?

 

Sounds like one of the modules inside the transmission may be going or has gone bad. My 02 Expy did the same thing. O/D light flashing on and off, transmission shifting harshly & acting funny. Ford dealer found one of the modules in the transmission to be bad. They replaced the module and Expy's been fine since. That was 34,000 miles ago. Not saying that is what's wrong with your Expy, but it is a possibility.

 

I had the exact same problem in my '97 Expy @80k miles. It turned out to be a shift solenoid. It was a $450 repair at the Ford dealer. Pretty much all they had to do was drop the tranny pan, replace the solenoid, replace the pan & top up the tranny fluid. That was about 30k miles ago. No trouble since.