1993 Dodge Caravan won't shift ?
 

This grand caravan is in 2nd gear it is driveable but it won't shift. It's a 3.3L engine and a 604 transmission.

By wont shift do you mean that the shifter is stuck in 2 or that the auto tranny wont shift passed second?

The transmission starts out in 2nd gear and will not shift to 3rd gear. The gear shift handle is not the problem.

Ok since you are sure it is not the selector in the van or the linkage itsself then here are a few more

1. make sure you have the proper level of tranny fluid
2. It may be a Faulty fluid pump if the tranny isnt getting enough pressure it isnt going to shift.

Does reverse work ?

if both of these check out then i would suggest unless you have experience with automatic transmissions it would be best to take it to a tranny shop. Auto trannys are quite complex inside.

Check out the transmission it would be helpful for you to start up again.