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Unread 10-10-2012, 10:59 PM   #1
taoshum
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Normal AT or Potential Problem?????

Yesterday, early, when the temp was in the low 30's I went out to start the Jeep and it started fine, put the AT in "R" and it will usually start rolling back slowly but today it just sat there. So I gave it a little more gas and it started going but felt different than all the times before. After backup to the street, going forward it seemed OK. After that, on the way to town and then coming home it seem OK again. This morning, it did the same thing. This has never happened before. I check the AT fluid level, it's OK. Whatever it is, it is gone after everything gets warm.

I'm probably being paranoid but changes get my attention, especially changes in the AT.

OK, fire away! Concern or ignore it...

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Unread 10-11-2012, 05:04 AM   #2
ronjenx
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Under what conditions did you check the transmission fluid level?

Warm up the transmission.
Park on level ground.
Let the engine remain idling.
With the brakes applied, run through all the gear positions, ending in park or neutral.
Read the level on the dip stick.

It should be at or near the "hot" marks.
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Unread 10-11-2012, 05:31 AM   #3
Wavedatya
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Could it be the break assist?


Sometimes in my jeep in gear it rolls and other times it sits there. This happens in reverse and forward. And has done it on all levels of incline including my gradual inclined driveway
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Unread 10-11-2012, 09:07 AM   #4
taoshum
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Quote:
Originally Posted by Wavedatya View Post
Could it be the break assist?


Sometimes in my jeep in gear it rolls and other times it sits there. This happens in reverse and forward. And has done it on all levels of incline including my gradual inclined driveway

Never heard of this "feature"... could be the answer? I'll
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Unread 10-11-2012, 11:13 AM   #5
MKWrangler
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It sounds perfectly normal for an automatic. Low 30's, thats about freezing temps which will make an automatic slow to respond. The fluid needs to be warmed up for it to operate correctly. You said it operates normally once it's warmed up which sounds normal for the conditions you describe.
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Unread 10-11-2012, 11:50 AM   #6
Wavedatya
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Quote:
Originally Posted by MKWrangler
It sounds perfectly normal for an automatic. Low 30's, thats about freezing temps which will make an automatic slow to respond. The fluid needs to be warmed up for it to operate correctly. You said it operates normally once it's warmed up which sounds normal for the conditions you describe.
Very true. Even in a manual transmission. When it reaches -20 here and you get in your car there is a lot that doesn't feel and sound right. The gear shifter feels like its full of glue until it warns up. That can't be healthy but its part of not living in a perfect environment.

To the op. if its worrying you have a mechanic look at it. They can tell pretty easily if its an issue. Take it to a transmission shop. If you don't like the answer or they seem to want to sell you a new tranny go elsewhere for a diagnostic. If there is a repeating trend than chances are you have issues. Next time you can find a incline. It can even be a steep one. Drive up and apply the brakes till you don't move. Let off the brake and see what happens.

I did this on my road trip out east. I was on a steep intersection and when I let off the brake she sat perfectly where I stopped. And with 10 seconds or so it will release and start to roll back. Or forward. I tried it multiple times and the brake assist seems to work pretty consistently. I believe this feature is more for a manual transmission and doesn't really apply to automatic. A manual transmission is tricky. When I learned to drive a manual I would actually plan my routes so I wouldn't get stuck on hill at a light. Taking off in a car rolling backwards isint easy at first
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Unread 10-11-2012, 01:01 PM   #7
ronjenx
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Quote:
Originally Posted by MKWrangler View Post
It sounds perfectly normal for an automatic. Low 30's, thats about freezing temps which will make an automatic slow to respond. The fluid needs to be warmed up for it to operate correctly. You said it operates normally once it's warmed up which sounds normal for the conditions you describe.
I would say not normal. The cold shouldn't make such a difference. ATF+4 has very good cold weather behavior.

Mine doesn't behave as you and the OP have described, even when it's well below 0F.
In fact, I've started and driven when it was -30F, and did not see what the OP describes. At that low a temperature, the shift schedule is modified, though. It gets back to normal, in stages, once the fluid temp reaches 80F.
This modified shift schedule would not change how the transmission shifts from Park to Reverse or Drive.

The only time I've seen a delay between shifting and moving was when the fluid level was a little low after a fluid/filter change.

There is quite a difference in fluid level between cold and hot. It's possible to have enough fluid in the sump to operate normally when the fluid is hot, but when it's cold in the morning, it may be too low to shift into gear as quickly as it would normally.

I don't know what may be the problem with the OP's transmission.
My first guess is low fluid level. If he has checked it correctly, there may be something else going on. I don't believe it's solely because the temp was in the low 30's.
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