Hey guys, nice site here.

Just bought a 96 Jeep grand cherokee, and i have done lots of maintenance on it. I changed the oil, air filter, gas filter, spark plugs, plugs wires, radiator fluid, and topped up the transmission (1.5 liters low). Topping up the transmission helped a bit with the slipping but, when it shifts from gear to gear with some heavy throttle (accelerating on the highway) the transmission will shift, but in between it revs for a second, like it was in neutral. The fluid is red, with a tiny bit of brownish in it, and doesn't smell burnt at all.

Also wanted to ask, with 257,000 kilometers is it a good idea to flush the transmission? Or is it better to just changed the fluid and filter in the pan?

Thanks a lot.

My 99 is doing something similar. Does your problem go away when its warmed up? Mine only slips when its cold.

both transissions are worn out

yea i believe it does go away when it's warm.

1st off, thanks, Jeepcherokeeforum! I found the answer to my problem through research on this site. My transmission slipping only happened at low RPM. Under accelleration, all was well. If I was up to speed, in town and going like 25-35mph, the transmission would slip out of gear. Afetr many searches on the net, I came up with the info that the TPS (throttle position sensor) was bad. At idle as in coasting the TPS tells the torque converter to drop out to let the Jeep glide. This all make sense to save on gas, brakes, etc. Now a defective sensor will tell the trans to drop out the TC a very low throttle. I replaced the TPS this morning and I am unable to produce the slipping. 1989 Cherokee 4.0L Select-trac is now shipping and holding perfectly!

Interesting... A mechanic in the shop at the dealership i work at told me it was the TPS and i never took it serious... and now i should replace it, since i am having the exact same issue. then apologize to him... Thanks for this post.

Pegriswo, did it trigger the check engine light when you were having the problem? Thanks

10/6/2013....Does anyone have any updates on whether the slippage is caused by a TPS, TCM or ECU?????
I have been looking for forum trends but my 1989 Cherokee Laredo 4.0L , 6 inline is still not working right.
I have replaced the TPS and have adjusted it as previously suggested......still at it

I hate to keep restating the obvious, but did you check the fluid level in NEUTRAL or PARK? it makes a BIG difference. It will show full in park when it's low in neutral. The pump is not pressurizing the system in park.