harrisgurl

Hi:

I have an 08 Sahara Unlimited-automatic
I have approx 98,000 KMS on it right now. (yes, I drive alot).

Yesterday I left work and got on the highway per usual. When I accelerated towards 100kms/60mph, it sounded as though it wouldn't go into 5th gear.
The RPMs were at a constant 38000-40000, but never went into the "red" 5-6 range.

When I pushed the gas down further, I did increase in speed, but the rpms stayed high and didn't return to the typical <3 range until I took my foot off the gas.

I put it in Neutral and then returned it to Drive...same thing happened. At low/mid speeds the behaviour was normal. This loudness and high rpm value only occurred when I punched the gas or was nearing/over 100kms/hr.

I pulled over, and checked fluid and for leaks. Levels were fine and no leaking. No noises that were unusual or clunking as I moved between park, reverse etc.

I slowly resumed my trip at that point. I notice the Overdrive button on the lower console (what a bad place to put that), but I frankly can't tell by that button whether it was on or off, and there was no light that illuminated anywhere to suggest it's status (which I am also questioning).

The same high "revolutions" and accompanying sounds happened when I resumed my trip and after about 20 mins of nervous highway driving I pulled over again--this time shutting the Jeep off completely while I contemplated my next move.

To my surprise, when I started it again and got back on the highway it was FINE. It went into high gear when my speed increased, and the revolutions dropped to normal range for the duration of my trip.

I know I have to take it in to be looked at, but before my dealership schools me and proceeds to charge me, I'm wondering if anyone has had this happen before or has any thoughts as to what this may be?

mike-d

Well there should be a light that comes on when you hit the OD off button on the instrument panel. It sounds like that might have been what it was. When you hit the OD off button the overdrive is obviousliy off. Once you turn the Jeep off, it goes back to normal and you will have overdrive. Also, I think that these auto's are only 4 speeds but I could be wrong in my interpitation of what that means.

harrisgurl

Thanks for your reply.

Ok, if it's not a 5 speed it's a 4 speed. Still though, it wasn't moving into that upper gear when it should have.

Re the O/D. I perfectly would have expected a light too...but didn't see one on the instrument panel or on what looks like it COULD be an LED beside the button itself. I pushed multiple times looking for lights, frankly and there wasn't one....

I'm not really sure I understand what O/D does....would it cause the jeep not to move through it's regular gears?

harrisgurl

I just checked-you are indeed correct. It's 4 Speed. Therefore rather than it sound like it wasn't going into 5th, I'll retract and say that it sounded as if it didn't want to go into 4th. (and it didn't based on my observation).

Please note--at no point did I have the pedal floored. It was gradual increase in speed.
Thanks

rinkishJK

yes the auto is a 4speed auto with overdrive.. lockup t/c...

harrisgurl

lockup t/c?

Sorry-what does that mean?

rinkishJK

lock up torque converter... it can either be unlocked, partial, or full lock, like when u are on the highway doin 65, 70 cruising.. if u listen, and watch the rpm's u will see and feel each shift. usually partial lockup is applied from 3 to 4 shift.. BTW u cant adjust, or make it unlock, or lock. its a function of the trans..
transmissions are really neat the way they operate!

mike-d

well that is wierd that you dont have a light. If you had one it would be on the cluster not the button itself hmm? But basiclly OD off keeps you from going into overdive. "No crap Mike-D" i know you know that. but it will have no effect on how your Jeep goes through gears. It simply keeps you in a lower gear to keep your RPM's at a higher level, for suchs things as going up hills and such. I am really thinking that you accidently turned overdrive off. If it does it again let us know. Also the bulb for that OD off light might be out. Wish I could help more.

yo_marc

It would be a good idea to keep an eye out for that problem again. Not to be a downer, but generically speaking OD is often the first thing to start to go in an older / worn trans.

Coverter lockup is another.. and they can be similar in perception. (TC lockup normally occurs around 40mph I believe).