I have a 1997 ford tarus and it shifts hard from first gear to second gear. and the check engine light just come on today. nothing is leaking from the car and other than that the car runs great for now.

Light flashing , diagnostic trouble code's stored . Have a qualified repair shop check it .

Have you checked for auto transmission fluid level? It needs to be Mopar ATF +4 ONLY, no other brand will work correctly. Check for major leaks. Check tranny for tranny codes NOT cel codes.

Your car has went into a fail safe mode, either one because the speedo is not the proper gear ratio for that particular vehicle, not all of them were the same, it depends on the exact model. For instance, a Tarus SE is different from a Tarus LE / SE / on and on, and if the gear ration is not correct, then the TCM will not ssend a signal to the shift solenoids to do their job thus the car wont shift. It sounds to me like your original issue may have been that the speedometer didn't function or work at the cluster, ad you've made repairs to the wrong part. Change your Spped Sensor, and it will be ok, IF the cluster is for that particular vehicle. If it is the proper part, your only issue is the speed sensor.

Btw, I’m available to help over the phone in case u need at https://www.6ya.com/expert/samuel_4e847b1ae10ff587

Check the help link mentioned below:----

Overdrive light in the dash blinks?

http://repairhelpcenter.blogspot.com/2012/01/overdrive-light-in-dash-blinks.html

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OD light flashing and transmission fluid leaking?

http://repairhelpcenter.blogspot.in/2012/02/od-light-flashing-and-transmission.html

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Also i suggest you to refer these gear shift issues, which are mostly noticed. These are direct links with appropriate solutions to the specific problems of gear ****.

GEAR SHIFT ISSUES

Gear indicator Shows "3" Instead Of "D"?

http://whoisbyme.blogspot.in/2012/07/gear-indicator-shows-3-instead-of-d.html

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2006 Chrysler 300c: Shifter Stuck in Park?

http://technoanswers.blogspot.in/2012/06/2006-chrysler-300c-shifter-stuck-in.html

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1998 Ford Expedition: Will not Shift Out of Park?

http://schematicsdiagram.blogspot.in/2012/06/1998-ford-expedition-will-not-shift-out.html

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Car will not move when in gear?

http://repairhelpcenter.blogspot.in/2012/02/car-will-not-move-when-in-gear.html

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Mercedes-Benz transmission sticks in first gear?

http://technoanswers.blogspot.com/2012/01/mercedes-benz-transmission-sticks-in.html

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Mercedes Benz not engaging in first gear?

http://technoanswers.blogspot.com/2012/01/mercedes-benz-not-engaging-in-first.html

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Chrysler PT Cruiser only goes in First gear?

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

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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

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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

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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

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Nissan Sentra stuck in park?

http://technoanswers.blogspot.in/2012/02/nissan-sentra-stuck-in-park.html

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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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Automatic transmission will not go into high gear?

http://howtobyme.blogspot.com/2011/11/automatic-transmission-will-not-go-into.html

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Car won't downshift sometimes?

http://schematicsdiagram.blogspot.com/2011/12/car-wont-downshift-sometimes.html

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Buick Park Avenue: Transmission will Not shift into drive?

http://schematicsdiagram.blogspot.com/2011/12/buick-park-avenuetransmission-will.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

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Ford Taurus won't shift from park?

http://schematicsdiagram.blogspot.com/2011/12/ford-taurus-wont-shift-from-park.html

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2006 Ford F150: Will Not Shift out Of Park?

http://technoanswers.blogspot.in/2012/06/2006-ford-f150-will-not-shift-out-of.html

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Car Transmission will not go into Park mode?

http://schematicsdiagram.blogspot.com/2011/12/car-transmission-will-no-go-into-park.html

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1998 Chrysler Voyager: Transmission Problem?

http://howtobyme.blogspot.in/2012/06/1998-chrysler-voyager-transmission.html

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Shift indicator directly goes to 2nd when key is turned ON?

http://schematicsdiagram.blogspot.com/2011/12/shift-indicator-directly-goes-to-2nd.html

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Third gear missing and engine losing power?

http://schematicsdiagram.blogspot.com/2012/01/third-gear-missing-and-engine-losing.html

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Chevrolet silverado has whining sound in gear?

http://technoanswers.blogspot.com/2012/01/chevrolet-silverado-has-whining-sound.html

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2002 Chevrolet Avalanche Z71: Gear shift Issue?

http://whoisbyme.blogspot.in/2012/06/2002-chevrolet-avalanche-z71-gear-shift.html

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Hard to shift gears on Manual transmission?

http://technoanswers.blogspot.com/2012/01/hard-to-shift-gears-on-manual.html

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Car hard shift at slow speeds?

http://technoanswers.blogspot.com/2012/01/car-hard-shift-at-slow-speeds.html

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Transmission-Hard To Down Shift

http://technoanswers.blogspot.in/2012/07/transmission-hard-to-down-shift.html

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Automatic transmission shift lever hard to move on cold mornings?

http://technoanswers.blogspot.com/2012/01/automatic-transmission-shift-lever-hard.html

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2000 Nissan maxima shifts hard?

http://schematicsdiagram.blogspot.in/2012/02/2000-nissan-maxima-shifts-hard.html

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Vehicle noticed sluggish delayed shifts while driving?

http://schematicsdiagram.blogspot.in/2012/03/vehicle-noticed-sluggish-delayed-shifts.html

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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

These details will help.

Thanks.

Hi Seth, Check out your engine and gear box mountings! Regards John

For Automatic transmission problem,click the link below:---- Automatic transmission troubleshooting:----

http://howtobyme.blogspot.com/2011/11/automatic-transmission-will-not-go-into.html

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Automatic transmission shift lever issues?-------

http://technoanswers.blogspot.com/2012/01/automatic-transmission-shift-lever-hard.html

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AUTOMATIC TRANSMISSION FLUID LEVEL? --

http://schematicsdiagram.blogspot.com/2011/07/how-to-check-automatic-transmission.html

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AUTOMATIC TRANSMISSION FLUID AND FILTER?

http://schematicsdiagram.blogspot.com/2011/07/how-to-change-automatic-transmission.html

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Transmission fault light on car dash?

http://schematicsdiagram.blogspot.com/2011/12/transmission-fault-light-on-car-dash.html

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Transmission shifting problem?

http://schematicsdiagram.blogspot.com/2012/01/transmission-shifting-problem-on-toyota.html

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Transmission Slips out of 2nd gear?

http://repairhelpcenter.blogspot.in/2012/02/transmission-slips-out-of-2nd-gear.html

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OD light flashing and transmission fluid leaking?

http://repairhelpcenter.blogspot.in/2012/02/od-light-flashing-and-transmission.html

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Why Transmission fluid leaks near radiator?

http://repairhelpcenter.blogspot.in/2012/02/transmission-fluid-leaks-near-radiator.html

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Transmission fluid leaking?

http://technoanswers.blogspot.in/2012/02/ford-windstar-transmission-fluid.html

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****** wont go in reverse?

http://technoanswers.blogspot.in/2012/02/dodge-neon-wont-go-in-reverse.html

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Automatic transmission will not go into reverse?

http://technoanswers.blogspot.in/2012/02/dodge-automatic-transmission-will-not.html

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Transmission is making buzzing noise?

http://technoanswers.blogspot.in/2012/02/transmission-is-making-buzzing-noise.html

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This will help.

Thanks.

You need to check the fluid and refill to proper level if low. And, if the fluid looks burnt (anything but a clear pink) it and the filter need to be changed. If that doesn't help take to a transmission shop to have it scanned because it could be a faulty or bad sensor.

Sounds like you have a severe vacuum leak. Poor vacuum will cause the trans to shift hard, very hard, and will also cause driveability concerns. Check all of your vacuum lines make sure they are intact, and not broken or leaking, and replace any that look questionable.

worn or damage mesh gear or worn synchronizers.

the idle air control solenoid or a vacuum leak on backside of intake the hose that goes to pcv valve.they are both common problems on this car.check for vacuum leak firstthanks for your question....