Thanks for choosing Just Answer . I'm Wolfgang here to help!!
I am confident we can resolve your problem together. Please
understand that I don't know your skill level. In most cases when you have a problem
with the way the vehicle performs, specialized tooling is required to acquire computer
data/information or engine testing results. We didn’t build these complicated vehicles; we
just diagnose and fix them. Also understand that I can't see, smell, hear, or touch the
vehicle either, so it may take a few replies to get to satisfactory results. I am also going to
direct you with the fastest, easiest and most common things to check first. Please be
patient and permit me to do what I do best.
I also try to give all of the information you may need, expecting a “positive rating” in
return. I will also continue assisting you after you have rated me, if necessary. If there
is any reason I cannot get a positive rating, please let me know why “in advance”, so I
can go another direction for you. I am sorry you’re having this problem; I’ll help you
Below is my first answer or request for more information. If you do not understand it, or you need more information from me, or need me to go in more detail.
The issue for the 3rd gear lock out is because the transmission control module is dectecting an error where then it defaults to 3rd gear to prevent more damage.
the way by your description is a excessive slippage fault . a scan tool is needed to see what fault is stored and then diagnose the issue at hand to find the root cause.
i can tell you to check this or that but its is not logical because it may be a big waste of time where the having the scan tool will shorten the diagnostic process and repair.
if you can get a scan i can assist. Durametric or the factory scan tool is the tool of choice!!