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Discussion Starter #1
Hi, I'm having erratic shifting problems and poor gas millage with my 2002 Santa fe. The issue began approx 2 weeks ago and is always present. The issue is hard shifting between all the gears, jerking, high tac revving , difficulty shifting from 3rd to 4th gear and throttle at times unresponsive, and like i stated earlier poor gas mileage.

This past weekend I replaced the TPS, but the TPS codes are still present. One concern I have with the replacement is that I din't detach the negative cable, which I've recently learned should be done. So I'm not sure if by neglecting to remove the battery cable I may have damaged the new TPS.

Is it true that the negative battery cable should be removed with TPS replacement?

I've also read that a faulty TCM can cause these types of symptoms as well and one resolution may be to reset the TCM by removing both battery cables.

Does anyone have any information on resetting the TCM?

Also, in case I decide to replace the TCM, can anyone tell me where the module is located ? Thanks all who reply and please excuse the length of the post.
 

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Hi,
The lenght of your post only is your least of worries, if any.
All these error codes, I cannot imagine they are real.
Like the code for barometric pressure low. Another about TPS, TCM etc.
I think you might have some electrical grounding problem, maybe related to the ECU.
This could give you stray ground voltage levels, transferred to the sensor voltage levels.
Many units in the car are grounded by grounding straps to a bolt to the chassis.
These connections could be compromised somewhere underneath tha dash or elsewhere.
Others have specific ground wires within the harness, like the TPS (actually two).
However, stray grounds are maybe difficult to find. There is a schematic of all the grounding straps at the Hyundai service site, you might want to visit.
So I wouldn't just start to replace all kinds of units (unless you have multi $$$$).
First diagnose voltages or function levels by exact measurements.
Furthermore, the reset you mentioned is done by undoing the positive battery cable and interconnect it for some time to the grounding cable at the negative pole ( or any other ground), I think for 30 seconds or so. This should then reset the ECU, I don't know if other units also are reset by that.

Good luck,
Paul
 

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Forget about the TCM, that's not the problem.

To test a TPS, unplug it. If your problems pretty much smooth out after unplugging, you know that's the problem.

The P0129 code might be a bad MAF, or maybe you drove it up a mountain and it produced the code. I'd clear the code and see if it comes back. Could be TPS related too.

The P1529 and the P0740 is likely due to a worn out transmission. When is the last time you changed the fluid?
 

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Discussion Starter #4
p1529 p0121 p0129 p0740

Firstly, thanks Paul and Jsinton for taking the time to address my issues and I assure you that the multiple codes are accurate. After your reading your reply I plan to take the following approach:

1. drive vehicle without tps and see if condition improves.
2. after TPS sensor test, replace TPS sensor and disconnect the MAS sensor and drive without the sensor to see if condition improves.
3. try to locate and verify the integrity of all the chassis grounds. Paul you mentioned a Hyundai service site, would you happen to know the actual site address? Also, am I correct to reset the ECM, the discharging procedure is to attach the positive cable to a chassis ground?
4. clear codes and see if the codes reappear after all test have been performed
`

As far as the transmission, the fluid was supposedly changed last year by a shop I used, and I provided the Hyundai fluid SP III, so the fluid had approx 2,000 miles on it. However, when I checked the fluid this week, the fluid was dark brown, didn't smell burnt but the dark brown color alarmed me especially with the extremely low mileage. I than changed the fluid myself 2 days ago, but the problem still exists. One thing worth noting is that the transmission has an internal filter, so I wondering if a flush would be better.

Again, thinks guys for taking time out of your day to offer all the wonderful advice!!!
Have a great day!
 

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Discussion Starter #6
thanks Paul. I one have one additional question at this time. My 2002 Santa fe has a factory alarm system with key-less entry key fob remote. Do you know if the battery disconnection will affect the remote function not allowing the vehicle to start? At this point just don't want to be stranded, and thought it worth asking before i proceed with the experiment. Thanks again for the advice.
 

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thanks Paul. I one have one additional question at this time. My 2002 Santa fe has a factory alarm system with key-less entry key fob remote. Do you know if the battery disconnection will affect the remote function not allowing the vehicle to start? At this point just don't want to be stranded, and thought it worth asking before i proceed with the experiment. Thanks again for the advice.
No, it won't impact your Fob from working.
 

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Hi Jay,
Would have been strange if it did, because then it would get a lot of people stranded when applying such a reset.

Johnaauld:
Can you enlighten me about which of the cars' devices such a reset will reset or is it only the ECU?
Thanks,
Paul
 

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Hi Jay,
Would have been strange if it did, because then it would get a lot of people stranded when applying such a reset.

Johnaauld:
Can you enlighten me about which of the cars' devices such a reset will reset or is it only the ECU?
Thanks,
Paul
That would require a technician of SBR711 caliber to answer.
 

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Discussion Starter #10
Ok guys got some partial good news. I disconnected the throttle position sensor and the erratic shifting has improved. I haven't tried the battery disconnect yet, but the only issue I now have is slow shifting. The truck now gets to around 4000 before shifting gears. Any idea what the issue may be?

thanks for the feedback!
 
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