Trans slips transmission slips and wont move

auto trans.101
1: check levels by the book, not like engine. RTM
2: check fuses.
3: scan it, or get it scanned. for transmission errors.
if car wont move and RPM goes high as foot presses guess
that is trans slip.
of RPM (engine) does not rise or only tiny,
that is lost engine power, total loss. but idle. (can happen)

sounds like a transmission issue does it go into gear does it try to move is it or was the trans slipping at any time are their any codes in the system

Sounds like you have definitely an internal problem in the transmission if its slipping ...

It could have an electrical issue as well like a faulty PCM .

How could the mechanic say its fine if it slips.....
I would start by going to a different shop/mechanic and have them scan the data to see whats going on electrically..but i would think at this mileage and with it slipping you're probably going to be looking at an overhaul/replacement transmission.

Your story really doesn't give us any trans history

You provided no vehicle,year,trans,trans fluid changes,
or any slipping issues that lead to where your at now

ANY SLIPPING AT ALL and you drive it a couple of days,
your going for a rebuild as you were told

There could be a number of different problems here, the first thing I would check or get checked is the transmission oil levels, most auto-matic trans have a bilt in safety, when the oil is low it will not engage or drive..

Check the fluid level in the transmission. If the fluid level is low, the trans will act as if it's slipping.

auto trans operates on fluid pressure. if the trans has never been serviced, more than likely the filter is plugged, and or the fluid is bad. no doubht its burned and will smell and look like it. get it towed to a shop and have the fliud and filter changed first, then check the band adjustment.recommend a trans shop do it and not jiffylube.

Causes could be:

• Low on trans fluid
• faulty torque converter
• low trans pump pressure
• Blown valve dody gasket
• restricted trans oil filter

Chk trans fluid with engine running in neutral! Bring to proper same same.

lol dont run over trees! seriously check shifter connection under chassis if off twisting under load may cause it to move, trans over heating, or trans may be in need of rebuild

sound like transmission slipping . check transmission fluid.add to correct level.