My 01 Caravan ES tranny is jumping after a complete stop.......It set 4 codes and the mechanic said the output speed sensor was bad. I replaced it.....well that seemed to have been the problem.....2 days later its jumping again but only setting 2 codes this time -> p0731 & p1790 What the heck is going on

Anyone

Those are codes associated with incorrect gear ratio. You replaced the output shaft sensor but this could also be caused by the input shaft sensor. a bad shift solenoid pack and tcm problems are other possibilties.

Do you come to a stop and then a few seconds later it jumps and feels almost like someone hit you in the rear ? If it does we called it Bump Stop. Its because the low/reverse piston does not engage in time when slowing down. Then after you stop it finally drops in. Usually the seal is causing it to hang up but we would replace the piston and retainer also. If thats it the trans has to come out. Ron

That sounds about right......it will jump 3 or 4 times before it stops and the whole time the speedo is bouncing even after it stops jumping. The speedo bounces in forward and reverse....dont know if that means anything....thought I would mention it...... Would this be an easy fix or should I be prepared to bend over for this?.... the van is in good shape but?????????

Have a good trans man drive it to verify that is definetly it. If it is you have two options. One you can replace the trans with either a reman or new one which the new one is more money. Or you can have a good trans person overhaul it and replace the low/reverse piston and retainer along with all the seals if thats all it needs. I dont know your milage on the trans but most times if it has alot of miles you will want to do a complete overhaul while you have it apart. I would get a price on the overhaul with parts and compare to the unit. It helps alot if you know a good trans person who might give you a break. We used to get 10 to 14 hrs to do a complete overhaul and flush the cooler and that includes R & R time also. I would think replacing or overhaul will cost at least $1500 unless you can get a break. Good luck , Ron

After you replaced the sensor you must clear all codes and quick learn the transmission control module.The quick learn must me done with a scanner,code reader do not have this function.Make sure the fluid level is topped of before you start.If the codes come back after the quick learn the you need to go deeper.