Most commonly this means that the governor pressure sensor and transducer need to be replaced,a volt code normally does not mean that there is a mechanical failure, normally this is a sensor issue
I use a fluid evacuator to pull the fluid out of the pan before I remove it so I don't spill it all over, if you do not have one be sure to leave one bolt in but loose on the side that you feel the fluid will drain from best and on the opposite side leave one bolt almost all the way in so as the pan comes loose it will tip to the other side and the fluid will poor out, than when removing the pan the rest of the way be careful since it will still be full of fluid
To avoid overfilling transmission after a fluid change or overhaul, perform the following procedure:
CAUTION: Do not overfill transmission, fluid foaming and shifting problems can result.
When fluid level is correct, shut engine off, release park brake, remove funnel, and install dipstick in fill tube.
I hope that this helps
if you need more information just let me know