2001 Hyundai Santa Fe hard shifting

2001 HYUNDAI SANTA FE
88,000 MILES • 6 CYL • 2WD • AUTOMATIC
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MICKELSONJ
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Encountered hard shift (wife) and check engine light. Code indicated output speed sensor and that was replaced. Initial test run OK, but wife said hard shift came again and check engine light came on. Performed "fuzzy" re-flash on TCM by touching both battery cables for 15+ sec. and check engine light went away. Test run fine for first couple of miles, but after running 40+ mph in cruise for a couple of miles, had hard shift down to third gear and engine light returned. Once this hard shift happens, the trans will not go into OD again unless the engine has been shut down and restarted. Hard shift is now exclusively from OD to third gear. Have not had car over 50 mpg or on highway; all in town driving.
No other fault codes beyond speed sensor.

What next?
Apr 20, 2010 at 1:45 PM
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KHLOW2008
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Hi mickelsonj,

Thank you for the donation.

Let me know the exact trouble codes etrieved.
Apr 21, 2010 at 9:13 AM
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MICKELSONJ
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There were two codes; one of which was P1529 and the other we didn't write down. One was for output speed sensor and the other was mfgr specific (not identified by Auto Zone reader).

Took car to dealer and got code for output speed sensor, but they didn't give us the code number.

Hope this helps
Apr 21, 2010 at 9:56 AM
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KHLOW2008
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P1529 = TCU request for MIL on/freeze frame to PCM via CAN

The above is the definition for the code found in our database. No diagnostic procedures are available.

Get the scan done again at Autozone and let me know the other code. That might be the main problem.
Apr 21, 2010 at 1:52 PM
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MICKELSONJ
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revisited Auto Zone and came up with two codes - P0720, Output Spd Sensor and P1529 which my wife said the dealer told her was "evaporative leak" (like a gas cap).

Auto Zone also said they'd exchange the spd sensor if I felt the one I got from them was faulty.
Apr 22, 2010 at 9:06 AM
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KHLOW2008
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I believe the P1529 is a reference code for the transmission having some trouble. Check the following to see if you can get any results.


https://www.2carpros.com/forum/automotive_pictures/192750_P0720SantaFe01Fig55_1.jpg


https://www.2carpros.com/forum/automotive_pictures/192750_P0720SantaFe01Fig56_1.jpg

Apr 22, 2010 at 10:39 AM
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MICKELSONJ
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Mystery solved. Finally gave up and took car to dealer who ended up replacing Output Speed Sensor. Car's fixed - runs fine.

Problem arose when Auto Zone read codes and sold me the wrong speed sensor. When questioned about that after replacement did not resolve problem, they continued to insist that the sensor purchased from them was the culprit. Learned a hard and expensive lesson.
Apr 27, 2010 at 2:20 AM
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KHLOW2008
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Glad to know you have fixed the problem.

The exact trouble code is required to identify the correct component and some generic scanners are not fully compatible and might provide a different code. At times a second opinion with a different scanner is required to reconfirm.
Apr 27, 2010 at 7:39 AM