It's a pretty common problem, first check the rubber boot that is around your shifter ( not the top one, the one under that ) many times pressure from the rubber bunching up will make it pop out.
Otherwise you'll be looking at a rebuild soon, the fork or collar for that gear is worn out, can't really say why except that the ax5 is famous for it.
A good indication of the fork being bad would be if reverse is affected too.
If yours is like mine, 5th gear is hardly ever used, so you could probably go quite a while without needing to repair the problem, but eventually the same thing will happen to the other ones too.
3.07 or 3.73 to 1
My jeep wrangler keeps loking in gears
Jeep Wrangler only,
80w90
If a 2000 Jeep Wrangler suddenly loses power in 5th gear, it might be a problem with the speed sensor on the transmission. This sensor regulates when the Jeep will shift or should shift.
Check where your gear shift mounts to the top of the trans, when that plate gets loose this will happen a lot.
Could be 3.07, 3.55, or 3.73
75w90 or 80w90
75w90 or 80w90
your shift lever bushings are bad, easy fix.
The 4 cylinder models have a gear ratio of 4.10:1
check the U-joints in the drive line