Trans drops into 3rd gear won,t shift to 4th

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
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Won't shift from 3rd to 4th gear - Lexus Forum Discussion
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RX300 not shifting into overdrive. - Lexus Forum Discussion
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FIRST POST! RX300 no 4th gear a full year. Fixes? - ClubLexus
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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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Yes, this could be the shift solenoid. Was the transmission filter changed at the same time as the fluid? Dirt in the system can affect some of the transmission sensors tripping Trouble codes. I cannot be sure what the P1732 code is as some codes can be very vehicle specific but it appears to refer to the transmission or on of it's sensors.

P0733 - Gear 3 Incorrect Ratio.
P0734 - Gear 4 Incorrect Ratio.

Im assuming it is a 4 speed transmission and if you are using the "tap shift" which is for performance situations and you wouldnt typically need 4th gear. What speeds are you trying to go into 4th? If you are going too slow it wont upshot because you rpms might drop too low. Will it not go into 4th at highway speeds?

when engine light is on pls go to nearest autozone and scan the car its free.and let us know whats the code.
Hope this will answer your question,If do pls click on helful botton and you can follow me at fixya,so I can answer your question faster.thanks.

When did you last replace trans filter and fluid? Dirt may be causing shift valve to stick.

then the problem will be in the wiring harness and connections

code p 0734 refers to gear 4--incorrect ratio===causes --wiring---TR sensor/ switch---shift solenoids---transmission mechanical fault
I would check the operation of the transmission ration sensor/switch first as that is the most likely place that the fault is
check engine lights are not solely for the engine but report on transmission problems as well
a transmission mechanical fault is the absolute last that you should consider because the transmission will revert to normal operations until it selects gear 4 which indicates sensor or solenoid problem

Engine Light ON (or Service Engine Soon Warning Light)
- Incorrect transmission shifting Possible causes - Low transmission fluid level
- Dirty transmission fluid
- Shift solenoids
- Transmission mechanical problems
- Transmission hydraulic control circuit Tech notes Start by inspecting the transmission fluid level and condition, and change fluid if necessary. When is the code detected? P0734 is detected when A/T cannot be shifted to the 4th gear position even if electrical circuit is good. P0734 NISSAN Description This diagnosis monitors actual gear position by checking the torque converter slip ratio calculated by Transmission Control Module (TCM) as follows:

Torque converter slip ratio = A x C/B

A: Output shaft revolution signal from revolution sensor
B: Engine speed signal from Engine Control Module (ECM)
C: Gear ratio determined as gear position which TCM supposes

If the actual gear position is higher than the position (4th) supposed by TCM, the slip ratio will be more than normal. In case the ratio exceeds the specified value, TCM judges this diagnosis malfunction.

Hi there,
that means 1,2,3 gears working so
What you can try is replace the 4th gear solenoid your car should have one solenoid per each gear so hope this helps...

The transmission may be in Limp mode. The transmission is on the same fuse as the MAF, O2 sensors and at least one other sensor - if an O2 shorts out, it will blow the fuse and the trans will go into limp-home mode. Be sure the trans has power and the fuse is not blown before doing anything else.

What is "limp-home mode" ? This is a fault mode in which the transmission either loses electrical power or the PCM deactivates all of the electronics. The transmission will default to max line pressure. The driver will have Reverse and 3rd, with manual 2nd available by putting the gearshift in 2 or 1 (doesn't matter). 1st, 4th, and TCC lockup will not be available. It will not hurt the car to drive it like this for short periods, but use manual 2nd to get the car moving, and be aware that the trans will generate more heat than normal while operating in limp-home mode due to increased torque converter slippage during 2nd gear starts and no lockup in 3rd gear.

Trans does not upshift out of first, speedometer reads zero at all times: VSS failure. Easy fix on rear of transmission, but xmember must come out to access VSS.

Car goes into gear but feels very sluggish like the brakes are dragging, but it will roll easily (starts out in 4th gear), you manually shift to 2 to get it moving, once it's moving you put it back in OD and the car shifts 3rd to 4th on its own and locks the converter at the appropriate time: ShiftB solenoid failed: Easy fix in the pan. Or a wiring problem from PCM to trans.. or PCM.

No 1st or 4th available; trans shifts 2nd to 3rd by itself in D or OD and locks the converter : ShiftA solenoid failed. Easy fix in the pan. Or a wiring problem from PCM to trans.. or PCM.

Transmission does not shift automatically, only manually. Swap in a known-good PCM, check wiring, check other sensors such as VSS and TPS.

3rd gear starts, can manually shift through all gears. When car has been turned off for a bit, then back on it will run normally.: VSS dropoff w/ Hi-stall converter. The rpms are too high, but VSS is showing no movement. Happens after a tire burning take-off. Doesn't store a code, will not throw a CEL (I've heard that it will store a code if it happens 3 or more times). Cure: Reprogram PCM for VSS dropoff -- PCMforLess knows about it.

Here are just some of the common things you have described with the issues your transmission has. Good luck and keep me posted.