While driving transmission wont shift into overdrive and when you turn overdrive button off it shifts into second gear

The Check Engine Light is on? Did you read the DTCs.

The second link has the answer, the first link says it is a known issue. It is times like this you need the Dealership or a good auto electrician.

Transmission won't shift to third until temp rise

ClubLexus https://www.clublexus.com > forums > 713188-transm...
Apr 1, 2017 - Transmission won't shift to third until temp rise ... The solution is to drive slow and keep rpms at 2.5k and 3k at max till the engine and transmission warm up.
Sometimes transmission wont shift from 3rd to 4th - ClubLexus
Aug 23, 2021
Won't shift from 3rd to 4th gear - Lexus Forum Discussion
Jan 25, 2011
RX300 not shifting into overdrive. - Lexus Forum Discussion
Jul 11, 2013
FIRST POST! RX300 no 4th gear a full year. Fixes? - ClubLexus
Jan 9, 2013
More results from www.clublexus.com

Owner of Lexus RX300 with 182000 miles. Recently the ...

JustAnswer https://www.justanswer.com > lexus > 3wsxt-lexus-rx3...
Aug 22, 2010 - Recently the transmission won't go into overdrive. Stays in 3rd gear like when you press the o/d button to do so. When car is cold (live in ...
1 answer · Top answer: Hello and thank you for using just answer! The check engine light is on correct?

https://www.google.com/search?q=Lexus+RX300+will+shift+into+overdrive+once%2C+and+after+slowing+down+it+won%27t+go+past+3rd+gear

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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.

Roger, that doesn't even make a whole lot of sense to me. If the overdrive is causing the transmission to slip, wouldn't it also cause the fuel mileage to go down? Are you sure the transmission is slipping? Or is the transmission simply shifting in and out of overdrive? If it is, is it shifting at the proper speeds? Driving at around 40 - 50 Mph will sometimes make the transmission go in and out of overdrive repeatedly. This can be perfectly normal.

Have you checked your transmission fluid level?

Is your overdrive off light flashing? If the transmission is actually slipping the OD OFF light should be blinking at you to let you know there is a transmission problem. Either that, or the Check Engine light will be coming on. In either of these cases, you need to scan your onboard computer network for possible fault codes.

For Automatic transmission problem,click the link below:----Overdrive light in the dash blinks? http://repairhelpcenter.blogspot.com/2012/01/overdrive-light-in-dash-blinks.html
--------- 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.

it may be a bad transmission modulator valve located on the side of your transmission,vacum operated. a sudden downshift or forward shift when unexpected is sign of a bad modulator valve or a vacum leak to the transmission.best to shop around for a garage w/references when it comes to transmission work though. check all the vacum lines to your transmision,you need to look on the underneath side of your truck on the side of transmission for a loose or disconnected vacum line on the side of the transmission. when you feel the vacum line,follow it to the top of engine,the vacum line is about 3/8th line,and may be disconnected or losing air. to make this short,when you drive the car,start out in low gear and shift the transmission,manually from 1st to 2nd to 3rd does it do right with no slipping? if it does this right and shifts great manually,the modulator valve on the side of the transmissions bad,or a bad vacum leak in-between.thank you for choosing fixya.com

Is your tow/haul button on? If not, it could be activated erroneously. It'll keep it from shifting into overdrive and locking the torque converter, and also keeps the transmission from shifting more often. If this isn't the issue, then you'll have to look into your computer, as the transmission shifting is controlled by the computer. The transmissions were the weak points on these trucks; only good for max 200000 miles, so if you're getting close, keep that in mind.

no you have a failed transmission on your hands, it is slipping.

your transmission is slipping

you may have damaged the overdrive gear, a local transmission shop would be your best bet. for good troubleshoting and estimate.