2001 Hyundai Elantra transmission temperature sensor problem

Tiny
MIKE2001HYU
  • MEMBER
  • 2001 HYUNDAI ELANTRA
  • 2.8L
  • 4 CYL
  • FWD
  • AUTOMATIC
  • 62,000 MILES
My 2001 Hyundai elantra has had some shift flares and twice gone into "safe mode" in about a years time. I recently had the car in for inspection and the check engine light was on. The mechanic put his scan tool on the car and it was showing codes for emissions issues. The mechanic repaired the emissions trouble but when I picked up the car he said it also said the transmission temperature sensor was saying it reads -40. I changed the sensor and drove the car a couple weeks. I took it back to him to see if the sensor would read anything different. He put his scan tool back on it and it still say -40. He tried to clear the reading but says it would not go away. Since then I tested the old sensor. It reads 8.36 ohms. The new sensor reads 10.23 ohms. The harness tests out at less than 1 ohm. The gray wire on the control module seems to be putting out 3.92 volts. Does anyone have a idea of what I should check from here. The transmission has not gone into safe mode for 4 months and the engine light has not been on for the same length of time.
Thanks,
Mike.
Tuesday, April 22nd, 2014 AT 4:40 PM

10 Replies

Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
It may be a connection, shorted /open wire or tcm. See pics.
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Wednesday, April 23rd, 2014 AT 7:09 AM
Tiny
MIKE2001HYU
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  • 6 POSTS
The TCM is putting out 3.92 volts on the grey wire that goes to the temperature sensor. The harness seems OK. The sensor is new. It isn't putting out a code. Just that the mechanic says the sensor says it is reading -40. If it turns out to be the TCM can I replace it with one that is the same part number. AND if so, is it a plug and play or does it need any type of programming.
Thanks
Mike
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Wednesday, April 23rd, 2014 AT 6:19 PM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
It will probably need programming
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Thursday, April 24th, 2014 AT 5:39 AM
Tiny
MIKE2001HYU
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  • 6 POSTS
What would I have to do to program it. Is that something a dealer has to do? Is the reading of 3.92 volts normal for the wire to the sensor.
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Saturday, April 26th, 2014 AT 6:15 PM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Previous reply said what the voltage is coming from the tcm. If you replace it a garage or dealer has to match it to your car. This may be another problem like a bad ground so check those for cleanliness etc. We don'thave much info on this code check thetwo areas i've poitnted out in pic one is ground going to tcm and theother is tcm ground there may be a bad conection the previous reply gives the correct voltage.
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Sunday, April 27th, 2014 AT 5:34 AM
Tiny
MIKE2001HYU
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  • 6 POSTS
Thank you for the reply. I will check the areas you point out and see what I come up with. The schematic you sent is excellent and should be a big help
Thanks,
Mike
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Sunday, April 27th, 2014 AT 8:03 AM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Tehre aretwo pulse generators that use the same ground so it may be a problem where they are all connected in harness or the pulse generators may be causing the problem as well.
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Sunday, April 27th, 2014 AT 8:20 AM
Tiny
MIKE2001HYU
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Well I did extensive checking of the wiring and the grounds. All of them checked out. I still cleaned up the grounds. Checked pins for bent/ corrosion and they all checked out. I did replace the input and output speed sensors before when this trouble started. I can't seem to find any trouble with the wiring
Mike
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Monday, April 28th, 2014 AT 3:52 PM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Well there isn't much I can tell you then sorry, i''ve gone to about the extent that I can thinkof with my knowledge. I have no further suggestions.
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Monday, April 28th, 2014 AT 3:59 PM
Tiny
MIKE2001HYU
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  • 6 POSTS
I think I might take it to the dealer and have them use there scanner to see what they find.
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Wednesday, April 30th, 2014 AT 6:04 PM

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