My 2004 montana shifts into 2nd an 3rd but wont shift into drive and there is no slippage

Could be a low pressure issue with the torque convertor.

cel means nana, scan it.

ok , as with all a/t
1: CHECK FUSEs.
2: Check levels, ATF
3: do the full flush and filter and pray magic. (i have no hope)
4: the more you slip it the more damage to those clutch packs.
diagnose slip, that is a big show stopper.
see thje on car tests for this A/T here.

http://www.jeep4x4center.com/knowledge-base/index.htm?utm_source=cj#service

change trans oil and new filter if problem still there it most lickely the shift modual

sorry tosay sounds like u need a transmission

Sounds like your transmission is in limp mode. This is a fault mode in which the transmission either loses electrical power or the PCM deactivates all of the electronics. The transmission will default to max line pressure. The driver will have Reverse and 3rd, with manual 2nd available by putting the gearshift in 2 or 1 (doesn't matter). 1st, 4th, and TCC lockup will not be available. It will not hurt the car to drive it like this for short periods, but use manual 2nd to get the car moving, and be aware that the trans will generate more heat than normal while operating in limp-home mode due to increased torque converter slippage during 2nd gear starts and no lockup in 3rd gear.

The other from what you described, trans shifts 2nd to 3rd by itself in D or OD and locks the converter : ShiftA solenoid failed. Easy fix in the pan. Or a wiring problem from PCM to trans.. or PCM.

Thank you for using fixya and have your Safari scanned for the DTC codes that would indicate what issues your transmission is having to put you in to limp mode.

shift modual and check the transmission fuse

MV could be the problem. Always work thru issue before buying ANY can of additive. Generally those things just mask the issue..not fix it. Change your fluid,and if that doesnt correct it,then take it in and have the tranny bands tightened. most shops do this relatively in expensively.

possiable tps sensor

I had this exact problem on my 2005 5.3L Suburban... It would shift into 1 and 2 and reverse, but not 3 and 4.

I took it into a transmission shop, and he said the 3-4 shift solenoid was burned up. Wanted 1500 to fix it. Far from home, so I have to pay it.

Rebuild the transmission