Why won't it shift into 3rd or 4th?

check and replace the TCM

well darla, im afraid you need new knee's!!LOL well ya need another transmission from a wreckers and if have access to a garage and toools and know how u might as well just get another engine and transmission set that has alot less km's than yours and maybe just maybe they might find u a tweaked out one!!! by tweak i mean already been hi-performinced!!!!!

time for a new one get one from a junk yard put it in or have someone do it for you

This button only makes the gearbox change from 3rd to 4th or 4th to 3rd, will not down shift in any other gear, make sure it is in 4th gear, usually above 60km, than press o/d off it should go into 3rd gear, if it does not than see a automatic specialist, it is usually a sensor, if you go to Toyota they will charge you a fair bit.

Does it stay in second or does it make the shift and go to neutral or first?

It is possible that the computer is the culprit. Most cars with computer controlled trannys will keep in 3rd gear and only shift to overdrive when the engine has warmed up sufficiently. It could be a problem with this system. The best place to take it is your local AAMCO or Mr. Transmission, or the dealer. A regular garage will just be guessing in some cases unless the problem is revealed after running the engine codes.

Ford is very common for tranny problems. Most likely your tranny will have to be rebuilt. As a mechanic myself, I would suggest taking to tranny specialist to see if i needs to be rebuilt, or if the electrical unit is faulty. It will have to be tested with voltmeter/ohmmeter/multi-tester

i supose u are talking about a strait shift tranny if so the tranny ha shifter fork in it for the gears that is what is broke it is not 2500 dollars worth if someone told u that take it some where else check other prices

sounds like it may be either a converter problem or u got some bad clutches in third in the case you need to go to a tranny shop.

yes i have heard of this and my friend is on the second transmission in his 2006 2500HD.the first time there was internal issues and the second time they ended up changing out the whole tranny.