i have a 1990 dodge 3/4 ton 4x4 , rite to the point , the truck shifts strong but when you are on the highway going up hill it wont shift down to 3rd gear it stays in overdrive , when i manually shift it to 2nd and build speed then shift it back to drive its shifts to 3rd then rite into overdrive , it has a push button for OD that lights up when pushed but does nothing , when ive hit hard bumps in her she will work again also the speed o meter doesnt show speed when OD doesnt work and when one works so does the other ...my question is where should i start looking for this problem ? ANY ! help would be much appreciated thanks ... you can also email me or post on here thanks again
dd90

 

A faulty lock-up solenoid can cause your problem. This can take a while to download but go to page 38 and then page 16.

http://www.scribd.com/doc/228727/Dod...Service-Manual