OK, yesterday I put a new water pump on my 1996 F250 7.3 PowerStroke with no problems. Let it run, no leaks and all is well. Then I drive it about 30 miles and the trans starts shifting extra firm out of the clear blue. Now the OD off light on the gear selector is flashing on and off all of the time and still shifting hard. It still goes into OD at correct speed. WHAT IS WRONG????? Looking for any and all the help I can get to figure this out. Thanks in advance!

 

The flashing light means you have a trouble code related to the transmission, you need to have a scanner to retrive the code. I would recheck your work and have the computer scanned to see what code is stored, this will guide you in the right direction.

The transmission is in "failsafe" mode because of the code, it will shift hard and there also will be no lock up of the converter clutch.