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Discussion Starter #1
Hello Everyone, New member here. I've gotten lots of help and insight this last year through your knowledge and expertise for my 2006 XK 3.7l 4x4 QT1. Bought used in Jan. 2010 and has 53k miles. I've been experiencing some very inconsistant shifting since owning this, especially going up long and windy roads. I'll be accelerating to the bend in the road at posted speed limits, or even turning right or left from straightaways, let off the gas to do the turns, and then resume acceleration. Sometimes it down shifts, and sometimes it up shifts. While it's deciding what to do, I have no control over the accelerator at all. I could push to the floor and nothing. Once it finds it's gear, everything is fine. Seems at times it doesn't know what gear to be in. The shifting is never hard, always smooth. Could this have something to do with tranny speed sensor?:icon_confused: Any input appreciated.
 

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Could this have something to do with tranny speed sensor?:icon_confused: Any input appreciated.
I think it is your ESP and/or Traction Control.
 

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Discussion Starter #3
I think it is your ESP and/or Traction Control.
I've turned the esp off and this still persists. I'm not too worried, again, the shifting is smooth, just kind of erratic at these times. Since I live in a hilly area, i'm always going through this.
Jeep 5253, do you know what the speed sensor does? Thanks for the response.
 

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Have you disconnected the battery to have the XK's computer relearn you driving habits?
 

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I've turned the esp off and this still persists. I'm not too worried, again, the shifting is smooth, just kind of erratic at these times. Since I live in a hilly area, i'm always going through this.
Jeep 5253, do you know what the speed sensor does? Thanks for the response.
I have no idea what a transmission speed sensor does, or if there even is such a thing. But there is a wheel speed sensor in each wheel well that senses the wheel/tire spin and if it detects slippage it activates the traction control.
 

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Discussion Starter #6
Have you disconnected the battery to have the XK's computer relearn you driving habits?
Yes, I've disconnected the battery, still happens. I'm guessing there is some lag time between shifts during these travels. If the shifting was harsh or severe, I'd be very concerned. I'm just puzzled by the lack of acceleration at these times.

Jeep, thanks for the speed sensor update. Had a leak this past winter, saw fluid on the transmission pan and assumed the gasket was leaking. Bought a new gasket/filter kit and did the repair. but there was fluid still dripping on driveway. After further inspection, found this group of wires going into the tranny, wet, running down onto the pan. Had the repair done for $125. My mechanic replaced the wiring harness going to several controls inside. Thought he mentioned some sensor that guaged speed or something, not sure though. Way to advanced for me.
 

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Yes, I've disconnected the battery, still happens. I'm guessing there is some lag time between shifts during these travels. If the shifting was harsh or severe, I'd be very concerned. I'm just puzzled by the lack of acceleration at these times.

Jeep, thanks for the speed sensor update. Had a leak this past winter, saw fluid on the transmission pan and assumed the gasket was leaking. Bought a new gasket/filter kit and did the repair. but there was fluid still dripping on driveway. After further inspection, found this group of wires going into the tranny, wet, running down onto the pan. Had the repair done for $125. My mechanic replaced the wiring harness going to several controls inside. Thought he mentioned some sensor that guaged speed or something, not sure though. Way to advanced for me.
Mine was doing some pretty eratic shifting before going to "limp mode". The problem turned out to be frayed wires on the passenger side of the transmission going to the solenoids inside. They ended up shorting out; hence the limp mode. The cure was tape all the wires individually and then tape them together. Seems strange that they would leave individual wires leading to the transmission rather than putting them in a wire loom or binding them.
 

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Discussion Starter #8
There's a guy at work that took his car to the dealer for regular service, not sure what he drives, and they told him there was an update they needed to install for the transmission. As a result, he gets much better gas on the hgwy, and its not shifting nearly as much. He attributed to previous frequent shifting to the 4cyl. engine.
I'm having frequent and inconsistant shifts as i've said in this first post. Any thoughts on the dealer "flashing" the computer to remedy this?
 

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The flash update for the Chrysler Transmission in the Jeep, is for the 545RFE, that came with the V8, the Mercedes W5A580 does NOT have a flash update. I would confirm all this info, I could be wrong.

BUT, the flash update for the V8 trans, would actually lower mileage and let it shift more often, because the previous programming to improve mileage would leave the vehicle torque converter locked up to much and try to keep it in higher gears all the time, best I can tell from posts describing it, they made the trans act more like it should, downshifting sooner, which hurts mileage, but does make the vehicle respond more like people expect.

Transmission speed sensors, usually there are two, input and output, for the trans controller to monitor the trans, and if its in the right gear and if it is slipping how the clutches are engaging, etc. At least in older Chrysler's, if the computers recognized a bad speed sensor, it would throw a code, that would be readable by doing the key dance to spit fault codes out in the EVIC or Odometer. (And I know I sound like a broken record on this guys) But, Chrysler's increasing move toward making everything proprietary in their vehicles over the last decade, you can't rule out those codes are stored in a way they are only readable with the Dealer Proprietary Tool, there are a ton of codes like that now, more than in the past.

Checking for Fault Codes should be your first step in troubleshooting any suspected problem. Most of the time, if there is a problem, the controllers will spot them and set a fault code indicating what they are.
 

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Discussion Starter #10
Thanks for thorough explaination.
I'll go ahead with an appointment to have the dealer scan for codes, since i'm sure the hand held unit i borrow from advance auto isn't capable of reading these.
 
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