Transmission stuck in third gear when selector in drive. works fine at times but not at other. problem seems to be electrical. is transmission shift electronic on hyundai grandeur 5 speed?

Yes ,you need to replace only ,after checking vacuum line that runs to it and make sure it's working correct

There are few related help links related to gear shift issues:----
Click the link below:----
Gear indicator Shows "3" Instead Of "D"? http://whoisbyme.blogspot.in/2012/07/gear-indicator-shows-3-instead-of-d.html 2006 Chrysler 300c: Shifter Stuck in Park? http://technoanswers.blogspot.in/2012/06/2006-chrysler-300c-shifter-stuck-in.html 1998 Ford Expedition: Will not Shift Out of Park? http://schematicsdiagram.blogspot.in/2012/06/1998-ford-expedition-will-not-shift-out.html Car will not move when in gear?

http://repairhelpcenter.blogspot.in/2012/02/car-will-not-move-when-in-gear.html Mercedes-Benz transmission sticks in first gear? http://technoanswers.blogspot.com/2012/01/mercedes-benz-transmission-sticks-in.html Mercedes Benz not engaging in first gear? http://technoanswers.blogspot.com/2012/01/mercedes-benz-not-engaging-in-first.html Chrysler PT Cruiser only goes in First gear?

http://howtobyme.blogspot.com/2011/11/chrysler-pt-cruiser-only-goes-in-first.html

Car is stuck in park and the shift will not move?

http://howtobyme.blogspot.com/2011/08/car-is-stuck-in-park-and-shift-will-not.html

2007 Ford Expedition: How to shift car in neutral with Dead Battery http://www.howtorepairguide.com/2012/11/2007-ford-expedition-how-to-shift-car.html 2002 Nissan sentra will not go out of park mode? http://technoanswers.blogspot.in/2012/02/2002-nissan-sentra-will-not-go-out-of.html Nissan Sentra stuck in park? http://technoanswers.blogspot.in/2012/02/nissan-sentra-stuck-in-park.html Car will not come out of Park?

http://howtobyme.blogspot.com/2011/11/car-will-not-come-out-of-park.html

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No First gear Starts In Second Gear http://www.howtobyme.blogspot.com/2012/07/no-first-gear-starts-in-second-gear.html Ford Taurus won't shift from park? http://schematicsdiagram.blogspot.com/2011/12/ford-taurus-wont-shift-from-park.html 2006 Ford F150: Will Not Shift out Of Park? http://technoanswers.blogspot.in/2012/06/2006-ford-f150-will-not-shift-out-of.html Car Transmission will not go into Park mode?

http://schematicsdiagram.blogspot.com/2011/12/car-transmission-will-no-go-into-park.html
1998 Chrysler Voyager: Transmission Problem? http://howtobyme.blogspot.in/2012/06/1998-chrysler-voyager-transmission.html Shift indicator directly goes to 2nd when key is turned ON?

http://schematicsdiagram.blogspot.com/2011/12/shift-indicator-directly-goes-to-2nd.html
Third gear missing and engine losing power?

http://schematicsdiagram.blogspot.com/2012/01/third-gear-missing-and-engine-losing.html
Chevrolet silverado has whining sound in gear?

http://technoanswers.blogspot.com/2012/01/chevrolet-silverado-has-whining-sound.html
2002 Chevrolet Avalanche Z71: Gear shift Issue? http://whoisbyme.blogspot.in/2012/06/2002-chevrolet-avalanche-z71-gear-shift.html Hard to shift gears on Manual transmission?

http://technoanswers.blogspot.com/2012/01/hard-to-shift-gears-on-manual.html
Car hard shift at slow speeds?

http://technoanswers.blogspot.com/2012/01/car-hard-shift-at-slow-speeds.html
Transmission-Hard To Down Shift http://technoanswers.blogspot.in/2012/07/transmission-hard-to-down-shift.html Automatic transmission shift lever hard to move on cold mornings?

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Vehicle noticed sluggish delayed shifts while driving?

http://schematicsdiagram.blogspot.in/2012/03/vehicle-noticed-sluggish-delayed-shifts.html
2007 Hyundai Santa Fe: Will not Shift out of Park Mode? http://schematicsdiagram.blogspot.in/2012/06/2007-hyundai-santa-fe-will-not-shift.html

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These will help.
Thanks.

Block the wheels and go under the truck, have a helper move the gear selector through the gear positions and watch the lever to see if it moves.

I would suspect you have a short in the wiring to the transmission or the shift solenoid inside the ****** is shorted. Only way to know for sure is to get the wiring diagrams and trace down and inspect all the wiring that the fuse powers.

if you have a modulator valve on your tranny it may be bad,the vacum could be restricted on it,the mod. valve controls shifts smoothly.lucas trans. additive helps with stuck valves in trannys,

The problem concerning low gear locked up sounds like a bad primary shift solenoid (located on the valve body internally) the other issue with the forward gear only engaging with the rpm up to 1800 could be inadequate hydraulic pressure (a transmission front pump issue), most likely there is no problem with the pump if when shifting the selector lever into reverse it engages quickly and normally. This may be a transmission computer issue and I would recommend having the dealership do a diagnostic check on the transmission to eliminate the computer as a culprit. transmission problems are very difficult to figure out and before spending a lot of money get the electrical diagnostic done first.

bad electrical conections on trany

I had a similar problem the reverse gear works fine but when i shift to drive the transmission runs
as if its stuck on third.
My problem was a burnt fuse located in the interior fusebox

no power stuck in 3rd gear electric shop unless youve burnt it up good luck...www.TransmissionGarage.com

You have an overdrive relay issue. The tansmission is really a four-speed box, but the OD selector either locks our fourth gear or allows the car to shift normally into fourth. I use the OD on my volvo all the time, because the revs drop in half when the OD is activated, The relay is located behind the glove box, toward the center console. $10 buck on Ebay and your transmission should shift correctly again. I would try that BEFORE more expensive fixes, like OD solenoid $200 or transmission control module. Just for kicks a picked up a spare ECU on Ebay for $10 because these get costly if and when they go. Easy fix, though, a couple of plugs.