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Discussion Starter #1
My wife's 2.7 Tucson 151,000 is having yet another issue. In the driving mode it will not upshift automatically? We can use the slap stick 1,2,3,4 and do it manually. Once in 4th if I let off of the gas pedal it downshifts automatically 3,2,1. It doesn't jerk (jerking= if I let off of the pedal quickly it feel like it never got out of 1st gear) if I start in 2nd gear and work my way up to 4th. I have just replaced the input & output sensors but to no avail. I am looking to go to Toyota & lease a car Pruis V Hybrid:frown::frown::frown: because then they will fix all of the problems? Can anyone help.
 

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Discussion Starter #2 (Edited)
I purchased new battery connectors & installed them even if the check engine light (CEL) wasn't on. I left the terminals off the battery for 24 hrs. I wanted to be sure to clear the codes in the tucson computer's memory! I reconnected the battery terminals & started it up. I went for a ride for about an hour & the non-shifting went away. It responded like there was no problems with the transmission. I headed home from the interstate to a traffic light light. Stopped & the CEL came on. That was a whole lot better than the non-shifting in Drive. Well tomorrow is an other day. I hope the struggles I have had helps someone? If it is electrical please remember to check the grounds to the frame of the car. I ran an extra wire under the bolt (that connected to the frame) to the negative battery terminal.
 

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Discussion Starter #3
The solution escapes me again. The driveability is again compromised. It doesn't shift out of low. I guess my next action is replace the ECU? If anyone has suggestions I am open to them!
 

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Discussion Starter #4 (Edited)
I spoke to my race car buddy yesterday about the 05 Tucson's shifting problem. He shared with me today that when hyundai Tucson had shifting problems & the sensors were changed the only other thing that he has run across is the computer for the transmission. He told me where to get the part. So I called them; picked up the part for $78. I got it home installed it on the tucson. The location of the transmission computer is to the left of the brake pedal under the dash. I removed the battery cables from the battery. Touched the cables together to ground out any stray electrical memory. I switched out the computer & went for a ride. It worked! It shifted in auto mode! Yeppee, Yeppee, I hope this helps someone else struggling with the same problem!
:)
 

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Been better of to maybe scan and see the offending DTC for the particular circuit that module seen fault in ??

Warning light on and up and erasing with out knowing what DTC stored is throwing away valuable info just to shotgun a pricey part on a hunch..
 
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