I have a 99 GC, auto transmission and all-wheel drive. When I am stopped in a drive thru that is on a grade, i can let off the brake and the vehicle rolls backwards like its a stick. When I giv er the gas to move up, the engine revs to over 2-3k rpms and it feels like the tranny is slipping. This is in while the trans is in drive and in all wheel mode. Not sure, this is my first 4x4 automatic. When I left the drive thru it drove as normal as it usually does, smooth. I am lost with this. Does Jeep have some wild angle sensor that tells when your on an incline and starts the trans off in 2nd? to avoid wheel spin, LOL, Strange.................... it has about 130K on the ole odometer. Bought it last weekend. Any help or ideas are most welcomed... Thanks in advance fellas.

 

Check the trans fluid. Is it full? Is the color red or a brownish color? Smell it. Does it have a burnt odor to it?
And Welcome to CF!

 

You might want to replace the filter IF the level is ok..

 

that sound like torque converter not locking-up. Clutches could be worn. I would try Lucas oil.

 

Have you experienced this Lucas oil? what is it a dexron III? i've heard of it before...

 

Torque converter clutches don't lock up at idle when the vehicle is not moving, only at cruise in high gear. The engine would stall if the clutches locked up at idle and standing still.

 

Check the trans fluid level first, then remove the trans control relay and drive the transmission manually shifting through the gears, if it slips in any gear or delays in forward then you have internally worn parts(bands and seals). If it shifts normally then you are looking at possibly the governor shift solenoid that is going bad or governor pressure sensor. Low/reverse bands is adjustable on that trans, but can only be done when the pan is down for a filter change.