'04 Hyundai Santa Fe 3.5L Hard, Lurching Shift into 3rd Gear

hyundai
transmissions
santafe

#1

Here’s the backstory,

For the past 3 months, upon shifting from 2nd to 3rd gear, the car lurches forward in a hard shift. Sometimes, it is nothing more than a benign “clunk”, and other times it is violent, as if hitting a wall. This does not happen every time it shifts and even under identical acceleration, the results vary from none to violent. The number of violent shifts vs. small jolts has increased over time, and all other transmission functions and shifts are fine/normal. After much time researching the inter-blogs, I have come to no consensus on what is causing this or how to fix it. Some say it is the adaptive shifting program and it just needs updating and others say it’s the tranny and a rebuilt tranny replacement is the only thing that eventually fixed this problem (though one posting on the Hyundai forum is of the same exact problem, but the solution is worrisome – contact negative battery terminal to positive, let sit for 10 min, reconnect, then drive at 1/3 throttle, shifting through all gears a dozen times. Poster says this resets adaptive shifting program and worked for him).

Finally, today, I took it in for a diagnostic with a local transmission specialist, and they could only replicate the hard shift once, but when that happened, he said the car went into limp mode and read two codes: P1193 and P2127. The car has never gone into limp mode (P1193) nor shown an signs of suppressed RPMs associated with this mode. Also, he seemed to focus his attention on the low voltage to the pedal position sensor (P2127) as being the major issue that is causing the hard shift. I also called a past dealer that worked on a similar issue with the car when I bought it used 4 years ago and they recommended updating the adaptive shifting program as they did last time; though I don’t recall if the shifting issue was the exact same problem I am having now. So, a few things I need help with:

  1. Does this sound like a computer issue or a tranny issue?
  2. Could the pedal position sensor having low voltage cause a shifting problem like this?
  3. Any merit to the connecting the battery terminals idea?
  4. Should I be wary of the mechanic that did the diagnostic today?

Thanks!


#2

Unplugging the negative terminal will do the same thing, clear the cars memory and revert to the manufactures pre-programmed computer modelling. No need to stick the ground to the positive. I would make sure the throttle code is repaired. The computer uses the throttle to calculate shift points and I would do that first.


#3

As mentioned above, definitely address the throttle position sensor issue before assuming the cause is something else. One of those on the fritz can cause an assortment of drivability problems.


#4

Hi Meteorologist87

Did you find a fix for this problem? I have the exact same thing now please tell me if possible.

Sam


#5

Hi Sam,

After the initial post, we ended up having the mechanic work on the car, which was entirely focused on the throttle issue. We picked up the car and the next day the problem returned (or it never really was fixed). We ended up leaving the car with them again for several weeks while we were out of the area, and they seemed to have fixed the issue in some way (but unsure as to what they really did). After 6 or so months, the problem returned. Since then, over the last 3 years, we have learned to live with this as a permanent issue. Over that time, it has gotten slightly worse, where it now shifts hard over 80% of the time under normal to fast acceleration. Within the last year, following the hard clunk into 3rd, the engine will rev up and down about 3-4 times per second for 2-4 seconds. During those few seconds, there is very little power/acceleration. This is not every time, but more than enough to notice it is not a one time fluke. Another thing I’ve learned, is that you cannot overcome this by using the auto-manual shifting (if yours has that). There is one positive I’ve learned though. If you accelerate normally, but then left off the gas and drop the rpms right before it shifts (feels like mimicking engaging a clutch in a manual), it rarely, if at all, happens. But you have to time it right.

All in all, we’ve found no solution that fixed it permanently. We never took it to a dealer to reset anything over the last 3 years, and have learned to live with it. The transmission is still going strong, and the car has had no other issues over the 60K miles we’ve put on it (minus an engine coolant leak that we just refill the reservoir every month).

Hope this helps.


#6

Thank you very much for your reply I still struggling with the same problem…Appreciate it