My rmz is stuck in 3rd gear it seems to be the selecta pin is that correct and if so is it a mission to fix?

You can get some information on this link: https://www.jeepgarage.org/threads/stuck-on-3rd-gear.9941/
Also get yourself a tester. I bought a 'BlueDriver'. It's blue tooth enabled so you can plug it into your car and run the test from your iPhone or others. You can also clear all the codes. Your Jeep s/b new enough that it'd work; worked on my '04 Ion.

automatic transmission?
we can not guess your skills
the question is how a tech can fix it not you, you have no tools
real.
what means 3RE? (why the RE there)"
ok typo day, 3RD (D is below E) got it.
now and answer and told here 10000 times and googled 1million times. or more
check all fuses
then scan the PCm (TCM) for DTC errors then we look them up in the real service manual and amazing it tells you what to do next
as in LOTS more tests with meters and gauges.
stuck in 3rd gear means what.?

1. shift lever stuck (as in will no move.
2. in drive, car starts off in 3rd gear, now that be rare. but possible.
3. in reverse cars goes forward but in 3rd gear.
4. or coasting the transmission never goes below 3rd gear called engine transmission natural braking actions and auto downshift features. happens foot off gas pedal.
5. or means overdrive or TCC lockup failing?

A/t boxes do lots of things, even wrong, but not told clearly here.

could be a trans speed sensor. trans mission could also need flushed and the filter replaced.

internal trans mission problem

Drive it slowly to a reputable transmission shop. There is nothing you can fix yourself.

Best guess is that the gear for 3rd speed is seized together with it's brass bushing and the center, large transmission shaft. I don't recall which gear is for 3rd, but the transmission has two gears (2nd and 3rd speed) which have brass bushings in them. The brass bushing should spin freely on the center shaft (when in final position - sometimes they pull off the shaft tough, but spin freely when in final position, my opinion is that this is OK), and the gear should spin freely of the brass bushing.
My guess is that the 3rd speed gear, being seized to the center shaft, cannot freely idle on the center shaft, which would result in being stuck in 3rd gear.

how do you fill it up and where is the filling cap??

dis canekt the batrey 4 10mins and than leter it till it gows up a ger and chek the oil in it

hello sorry but you will need to have trans rebuild done godbless

My 7 speed bicycle gears are not working correctly. 3rd gear is now tougher to pedal than 4th. Something is making a clickling noise and it seems that the gears are slipping. I am thinking that something was shaken loose while transporting on a bike rack for 14 hrs. Any suggestion on fixing it other than taking it to a bike dealer?