Autoshift gets stuck in 10 gear

[sbtrucking]

Can high voltage couse this?
I noticed voltage getting higher lately around 14.3v to 14.7v depending on load,
If I turn the engine off sometimes i turn the key to crank and nothing,
Need to wait a minute or two to try again, posibly things heating up?
It gets stuck in 10th little more often now every few hours driving.
All the connections are tight.
I may put a new alternator when the truck gets back to see if that fixes the problem