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rmorman 06-18-2011 02:03 PM

2006 jeep wrangler auto transmission
Just joined today and needs help. When the jeep is cold and you start off the rpm's will go up to 2000 and stay there forever, when it finally shifts it will lung or jump and makes a real loud noise in the rear end. We have replaced all the senscors that can be replaced twice. After it gets warmed up it will shift fine. We had a mechanic at a dealership tell us this jeep was made to shift hard. I don't believe that. We bought this jeep brand new and we have had this problem for almost a year now. I took it to a transmission person and he put it on the machine, I traveled about 50 miles. The machine read that the transmission fluid was showing the temp to be 1600 degrees. He told me he could not believe that the jeep did not catch on fire. Has anyone had this problem? Or is there anyone that can help us figure out what is going on. This jeep has not been abused at all. It has been in 4-wheel drive 4 time since we bought it, it has not been in any mud at all.

Rubicon2 06-18-2011 02:13 PM

Well I would definitely say there is something wrong with a temp sensor somewhere. There is no way the trans temp could reach 1600 degrees. As for the hard shifting my Jeep with 85,000 miles on really cold mornings shifts hard but that is because the fluid is cold and the TC won't lock up until it reaches operating temperature causing the RPM's to run a little higher. Other than that I'm not quite sure. When you say hard shift how hard are we talking here?

Shelby427 06-18-2011 04:15 PM

Yep the ECM reads the temp sensor for coolant among other items to set idle speed.
The IAC controls the idle via the ECM.

The tranny guy was pulling your chain, no way it got to 1600 degrees, you would have had puddles of molten metal.

But it may be a clue to where your problem lies. If memory serves me, your jeep has a temp sensor built into the range control in the valve body of the trans, it reads the sump temp.. If it's faulty it could be telling the ECM that the fluid is cold so the ECM holds the rpm's up to warm up the trans fluid.

And until the ECM starts getting readings from the other sensors saying that the proper temps have been met, it won't drop the idle, and ignore the trans sensor reading.

Normally though this would set a code.

herbie 06-18-2011 04:59 PM

yes temp sensor is likely faulty the oil would vaporize at that temperature as for harsh shift it may be possible that the temp reading could cause forced convertor lock up (been a while since building trans days but one method to cool the oil is forced lockups/may or may not apply to jeeps someone with more recent exp may have that answer)

Jerry Bransford 06-18-2011 07:17 PM

So the rpms jump to 2000 with the transmission in Park immediately after starting your Jeep? If so, that's not caused by the transmission. Has any work been done to your Jeep that would have required the intake manifold be removed, or where any of the vacuum lines could have been removed and not replaced, or broken so a vacuum leak exists?

Any type of vacuum leak can cause excessively high engine rpms.

rstewart 07-09-2011 08:02 AM

just joined and found this post.

i have a very similar problem (if not the exact same).

i just purchased my 2006 wrangler SE (4.0L, 33K miles, auto, soft top, 31" tires, no lift, winch, all else factory) last week.

the scenario:
walk out hop in the jeep to head to work. starts fine. revs normal. shift into drive and crawl out of the parking lot and onto the street. the jeep refuses to shift out of 1st gear until after 2000K revs (or helped along with sudden application of the gas pedal). when it does shift, it is a sudden, jerking, lunge forward accompanied by a loud popping sound (from underneath). the shift from 2nd to 3rd is the same only less severe.

after driving a few miles, and everything warms up, the tranny acts and sounds normal both on up and down shifts. the ride home from work is the same story as above

i haven't had a mechanic look it over and haven't done anything except check the tranny fluid (100% normal).

i read another thread 06 TJ Auto-tranny Shifting hard - where the problem was eventually fixed replacing the PCM.

any thoughts or should i bite the bullet and head to the nearest dealership?

thanks all.

jrussblues 07-09-2011 08:30 AM

1st gear shifting at 2k is normal for me, has been since i bought it. The tranny is run off of the ecu only. You also probably always shift into overdrive at 45 mph.
As for the pop sound. I would verify that the right type of fluid is in there before you start dropping money on an ecu.

rstewart 07-09-2011 10:47 AM


Originally Posted by jrussblues (Post 1365306)
1st gear shifting at 2k is normal for me, has been since i bought it.

the only reason this troubles me is the severity of the shift and the popping clunk from underneath...and then how it disappears once warmed up. i din't know if this was a know issue that i should be worried about (hate to crater a tranny) or something that everyone with a 2006 TJ has to deal with.

my last TJ ('98, 4.0L, auto, totaled last month) had a hard shift between 1st and 2nd but not as severe as my current TJ. plus, it's hard shift was constant, regardless of trans/engine temperature.

thanks for the response.

mekanimation 07-10-2011 04:22 PM

Same Here!
I have been writing in another thread about this issue. I have EXACTLY the same problem with my 06 LJ with 50k miles. But mine was giving temps in the -100 degree range. I've had it in to a Trans. shop 3 times trying to figure it out. Replaced the solenoid pack with the temp sensor on it. It worked fine until I drove it a longer distance then went right back to being a pig going out of first into second. It seems like the only constant is clearing the codes makes it work ok for a while. Therefore it's going into a dealer this week probably have to replace the PCM. I also realized that for whatever reason this model year got a much shorter warranty. BooHoo.

rstewart 07-11-2011 06:46 PM


let us know how your trip to the dealership turns out. I'm very interested in the results and what the mechanics have to say about the problem.

thanks for your post.

mekanimation 07-12-2011 12:31 AM


Just messing around in the driveway, I tried the disconnect the battery for a while trick. It worked to reset the computer on my own! Give it a try some time. Pull the negative cable off the battery while its parked (at least 10 mins I think). If yours is like mine it will run great until you take it on a longer drive. Definitely helped convince me that the problem is computer related.

rstewart 07-13-2011 07:10 PM


i did a "force flash" as noted here

it's like your technique, only it includes the turn key on, turn lights on and off and then turn key off.

started the jeep up and took a spin around the neighborhood. to my surprise, the transmission shifted at 1500K without any lunge or popping in the driveline. this was just a short drive but it has to be the PCM.

when you say, "long drive", how long are you talking about? 20 miles? 50 miles? more?

thanks for the update. i'll have a clunk-free jeep for a bit.

rstewart 07-14-2011 06:07 AM

apparently a "long trip" is 10 total miles or so—about the distance i drove after flashing the ECU/PCM. the transmission started acting up again on my way into work. super boo...

jarradfiorito 07-14-2011 10:41 AM

i have the exact same problem with my 2006 auto trans. when going from 1st to 2nd it kocks real loud and pulls...feels likethe trans is going to break almost...but after i drive for 5 or 10 mins this doesnt happen going to try a superchip flashpaq to calibrate all my mph and stuff

rstewart 07-15-2011 06:27 AM


let us know how that plays out. good idea. if the flashpaq solves the problem and keeps it from coming back AND increases power/economy...then i think that is the way to go versus getting a replacement from the dealership.

thanks for you post.

burntorangelj 08-10-2011 07:58 PM

Seems many are having this problem! In a little over a year i have had the following done to my 2006 jeep unlimited:

Trans rebuilt twice ( second under warranty)
New radiator (because trans was overheating)
Water pump
Trans cooler (direct fit for 2004 -2006, go figure)
Computer updated
Shift module replaced
And last but not least rear back up light wired jumpered due to it inducing voltage on temp sensor. Just drove it for over 200 miles and it just start shifting hard between first and second during the first few minutes driving. My guess bad ground somewhere? Suggestions are welcome?:-)

cbooth 09-03-2011 07:39 PM

My stock 2006 Wrangler is experiencing the exact same problems. Has anyone had any success with the superchip flashpaq? Or replacing the PCM? And if anyone has replaced the PCM, what was the damage?

herbie 09-04-2011 10:08 PM

more of a rant but its unfortunate they started putting transmissions under electronic control as opposed to hydraulic as has always been the case over the years. just turned a good system into crap that the average guy cant diagnose nor a lot of trade mechanics for that matter and cost more to fix.

jarradfiorito 09-06-2011 04:35 PM

ive fixed my knocking problem when shifting good enough so that it happens less than 1/10 of what it used to. when i checked my transmission fluid level i noticed it was EXTREMELY high. i siphoned out about a 1/3 of a gallon of fluid to bring it down to the proper level...this made it happen about 1/3 or 1/4 as much....after a week or 2 i just decided to find out what kind of transmission fluid was in the jeep from the factory and i siphoned out every drop i could and brought it back up to the proper level with fresh fluid

Opentop 09-07-2011 11:46 PM

My 2006 LJ just started lunging also from first to second, 53k miles

aaconductor 09-08-2011 08:55 PM

I have the same issues with my 2006 rubicon, when the jeeps sits off for a bit (duration differs but usually less then five minutes) and then start and drive away it revs to 2000 to 2200 rpm and then gives a whiplash shift, then after a few minutes of driving it seems fine. Occasionally (for about 1 week) it shifted perfect, other times the shift points just feel off and about half the time it shifts so hard it about knocks my teeth out. I've also noticed when I shut it off, after about a minute or so I hear gurgling as if there is a leak in the tranny and sounds as if something is bleeding off like a stuck solenoid or such. Im thinking there might be some air in the tranny possibly which could cause some malfunction which would also make sense why the shift points are off. Also if I start the jeep and let it idle for 15 or twenty minutes It doesn't shift hard or at 2000 or so rpm, it shifts normal. Thats why I feel it might be related possibly to air in the system. Just some fyi to those who have this problem it's in my opinion that my recent locker helical gear failure was due to these ridiculous shifts and the helical gears seem to be the weak link, since my jeep only has 16000 miles and is wheeled lightly this is probably the culprit. Not only is the tranny junk, but it is going to cost me a load of cash to replace the locker and problem still exists.:banghead:

wtchtfl 09-09-2011 06:15 PM

I had the same problem with my 2006 TJ with 143,000 miles on it. Started back when it had 34,000 miles on it after I replaced the fluid I would take off and the RPM's would be up there before it jumped,snapped your neck,knocked your glasses off along with the mud underneath the frame with a sonic boom shift.(I would cringe before "The Shift").
I finally figured out that it was too much fluid. After warming up the Jeep to normal temp sittin on level surface check dipstick it HAS to be at the 3rd hole from the bottom no more no less. This will solve your problem believe me.

T_MacP 09-09-2011 06:54 PM

Regarding the same cold shifting problems, the dealership very recently replaced the PCM on my 06 LJ Rubicon with 45K miles. They initially replaced sensors, but the cold shifting issues continued. After the PCM replacement, it shifts great.

rstewart 09-13-2011 10:02 AM

so, from what I keep hearing is that the only "real" fix for the problem is to replace the PCM? if that's the case does that fall under a warranty or possibly a recall?

I was chatting with a mechanic friend and mentioned a possible cause that I hadn't seen before. he said that possibly the previous owner of my jeep might have filled or topped off the tranny with the wrong type fluid. thoughts? I dunno if that would cause the tranny to shift better as you drive it.

Sweat it 05-28-2012 12:26 PM

I have the same problem, 2006 wrangler SE 4.0L, 12K miles, auto, bone stock, not sure what steps to get it fixed? Trans fluid is good. If i disconnect the battery, it will be good for 4-5 days before acting up again. which seems to be a computer problem but not sure. How much would a computer cost? or maybe a reflash(not sure what that would do)? I love my jeep, but may have to sell it soon if its not fixed soon. I cant afford a trans right now. Any help would be great. Thanks.

jcruz06 05-29-2012 07:42 PM

same problem
I am also having the same problem with my 2006 wrangler rubicon I was wondering if the ultimate fix was found

AFMAN23110 05-30-2012 04:00 AM

Another here with the exact same issue:

The Jeep seems to "lunge" or shift very roughly into first or second gear (Right around 15 mph) and then at times will not downshift say when you're coming up on a stop sign. Then it'll take excess RPM to get the vehicle moving, upwards of two to three thousand RPM to make it to 10 MPH. Though, once you get it beyond that 1st-2nd gear threshold it shifts just fine into 3rd and so on.

After driving for about 10 minutes or so, the problem disappears, maybe a little rougher shifting than normal but it goes through all the gears and shifts like it's supposed to. It's just at the start that it really has difficulty, serious difficulty.

I've checked for leaks, the fluid is pink and doesn't smell burnt, and I've added some Friction Modifier which hasn't helped either. Though the levels are a bit high.

The Vehicle is a 2006 Jeep Wrangler TJ X, 6-cyl 4.0. Automatic with 62,000 miles.

I just got the thing 2 months go and would really like to avoid a 1500 dollar tranny rebuild.

Any suggestions?

Neil F. 05-30-2012 09:01 AM


Originally Posted by AFMAN23110 (Post 2417225)
I've checked for leaks, the fluid is pink and doesn't smell burnt, and I've added some Friction Modifier which hasn't helped either. Though the levels are a bit high.

Friction Modifier? Friction Modifier goes in the differential for limited slip differentials. What kind did you add to the transmission? A quick web search indicates discussions of adding friction modifer to various ATFs but it appears to be highly unrecommended. To start with, do you have the correct fluid in the trans? Chrysler is ATF+4 ONLY (AFT +3 was the previous recommended prior to 00)

jcruz06 05-30-2012 09:14 AM

I just had a transmission flush and the fluid changed I am assuming he used the right fluid I took it to a transmission specialist

Neil F. 05-30-2012 09:53 AM

Was it having the problem before or after the trans shop did the work? Did he tell you about adding modifier? While I am NO trans expert but do read a lot of forums for the two Chrysler vehicles I have. Many vehicle manufactuers have their own recommend blend of additatives that go into their recommended ATF. ATF+4 is Chrysler only. Some transmission shops will use other ATFs and add items to "make it ATF+4" but from all the reading, that may not work. The Chrysler trans can be very pick on what it needs to work. I'd ask the shop specifically what fluid they used to start with.

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