Over Drive Transmission Issues?

[designsltd]

We have a 2000 rx 300 which recently will not shift into high (4th) gear/overdrive. It will shift in auto and manual thru 1-2-3 but will not shift out of 3rd gear into overdrive 4th . this occurred previously at one time, however the problem seemed to correct it self with in a short period of driving. Now more recently the transmission will not engage overdrive, when I execute the over drive button it has no affect to engage or disengage the transmission function. the rx 300 will shift through first 2 gears with out issue in auto and will manually shift 1-2-d into 3rd. but no shift into over drive.

Any ideas out there as to the problem? a electronic issue? module? seems like it is some type of electronic module/sensor which affects the over drive selector.

[wwest]

If the engine cannot provide the power level required at the low RPM in O/D at a specific roadspeed then O/D will not be engaged.

Miles...?

[designsltd]

If the engine cannot provide the power level required at the low RPM in O/D at a specific roadspeed then O/D will not be engaged.

Miles...?

169,000 the rx seems to be producing good consistent rpms in first 3 gears...it will stay in 3rd gear and than the rpms just continue to rise as the speed increases...where typical the vehicle engine would be running @ 2,000 rpm at 60 mph now the engine pushes to 3500 rpm at 60 mph. you can tell it is at that point to "shift" but it does not and the only way to get to higher speeds is to continue to push engine rpm higher...which of course outs greater strain and gas consumption on the engine. right now at 2,ooo rpm in drive i am getting @ to speed @ 40 mph.

both in auto and manual shift mode the car / engine seems to move through the L-2-D (1-2-3) shift gears w/o too much issue or problem but it will not go into O/D. If I engage or disengage the O/D switch it has no affect.

any thoughts, insights or ideas as to the problem or solution?

my o2 and air flow sensors , I believe are shot and in need of replacing (check engine light on and codes accordingly).

This is the first and only significant issue I have had with the 2000 rx 300 since new original owner.

please let me know as it is difficult to drive at low speeds and the starin on engine gas consumption at higher speeds is costly.

[wwest]

If the engine cannot provide the power level required at the low RPM in O/D at a specific roadspeed then O/D will not be engaged.

Miles...?

169,000 the rx seems to be producing good consistent rpms in first 3 gears...it will stay in 3rd gear and than the rpms just continue to rise as the speed increases...where typical the vehicle engine would be running @ 2,000 rpm at 60 mph now the engine pushes to 3500 rpm at 60 mph. you can tell it is at that point to "shift" but it does not and the only way to get to higher speeds is to continue to push engine rpm higher...which of course outs greater strain and gas consumption on the engine. right now at 2,ooo rpm in drive i am getting @ to speed @ 40 mph.

both in auto and manual shift mode the car / engine seems to move through the L-2-D (1-2-3) shift gears w/o too much issue or problem but it will not go into O/D. If I engage or disengage the O/D switch it has no affect.

any thoughts, insights or ideas as to the problem or solution?

my o2 and air flow sensors , I believe are shot and in need of replacing (check engine light on and codes accordingly).

This is the first and only significant issue I have had with the 2000 rx 300 since new original owner.

please let me know as it is difficult to drive at low speeds and the starin on engine gas consumption at higher speeds is costly.

At 169,000 miles you shouldn't be surprised that the engine/transaxle ECU has "learned" that it cannot rely on the engine to produce enough power to "cruise" along in O/D. Unplug the battery for ~10 minutes and the O/D will probably work again until the ECU (re)learns the (tired) engine's power limitations.

[lenore]

I think you all have missed the boat, Sounds like the valve body assembly is dirty and the overdrive shift solenoid is failed or sticking. I hate to tell you but the tranny is about to go out. Mine failed as your did. Does the fluid smell burnt when you check the dipstick? If it is black or very dark brown, it is probably going to fail completely soon. The dealer would doubtfulling clean the valve body assembly for you, but a tranny shop might. A fluid flush might make it worse. Good luck...

[wwest]

I think you all have missed the boat, Sounds like the valve body assembly is dirty and the overdrive shift solenoid is failed or sticking. I hate to tell you but the tranny is about to go out. Mine failed as your did. Does the fluid smell burnt when you check the dipstick? If it is black or very dark brown, it is probably going to fail completely soon. The dealer would doubtfulling clean the valve body assembly for you, but a tranny shop might. A fluid flush might make it worse. Good luck...

It seems to me that if the ECU commanded a move to O/D and the transaxle didn't actually engage the O/D clutch and/or didn't move to the O/D gear ratio there would be a diagnostic indication in the instrument panel. Whereas if the ECU never tried to move to O/D.....

Fill with premium fuel to slightly increase engine performance, disconnect the battery for 10 minutes, and then discover if the ECU commands O/D until it "discovers" that the engine lugs/knock/pings at the "lower" RPM in O/D, well OFF the engine's peak power point.

And be sure and check that the "O/D off" lamp comes on without starting the engine, hasn't failed.

[lenore]

Sorry West, I forgot that these cars do give some indicators when the tranny messes up....

[wwest]

My 01 RX300 will not shift into O/D until I reach a point about one mile from home. There is a temperature sensor in the transaxle but I don't know if it uses that or engine temp to keep it out of O/D until warm-up. In any case apparently a temperature sensor failure, always indicating "cool", could be your problem.

[blk_on_blk]

Interesting thread, for I am having the same issue... and one commonality I see is that this only started to happen when my check engine light came on. I had a coil go bad (which I just replaced) and now I've got an EVAP control code showing, so the light is still on. Does the tranny maybe no shift into O/D when the check engine light is on? Hmm... I don't think so, for I had it come on a while back, and before i could pull a code, it went off later that day... and it went into O/D just fine. Hmm, maybe certain codes cause the tranny not to shift into O/D. Maybe designed in there so you won't keep driving with certain codes showing?

Do you think if I drop the battery connection for a few minutes it might reset?

[blk_on_blk]

Okay, so I just dropped the battery cables, cleaned them, let it sit a bit, then put them back on.... and VOILA!! Everything back to normal... engine light off, transmission shifting fine, runs smooth and clean like new again!!

So, it sounds like Wwest was right, in that the ECM was telling the tranny the engine didn't have enough power to go into O/D. In my case, it was because of a bad coil. Even when the coil was replaced, the ECM wouldn't recognize it and apparently the codes were stuck in the ECM (so much for 'self-learning'). Once I pulled the cable off the battery and let it reset, everything read clean. So, I'm guessing the EVAP code was in conjunction with the coil failure.

Either way, the tranny not shifting into O/D doesn't mean it's failing, especially if the check engine light is on.

Alright... all fixed...... let's hope it stays that way!!!

[Mikemikemikemike]

Greetings to all - hope you are doing well where ever you are.  I just bought a 2003 Lexus RX300, 190k miles, and it has the vibration thing after 40mph, and also won't shift into 4th sometimes.  It also had a small exhaust leak.  I got that fixed with a flex hose for $180 at a muffler repair shop an hour ago.  It still has the shuttering above 40mph and the high RPM as it won't shift into 4th.  I'm being optimistic that the exhaust leak caused the other issues and will try the computer reset.  The repair guy said my tires need to be balanced just by looking at them - some kind of homespun lead weights.  I'll take it in tomorrow and get the tires replaced/rebalanced depending on what the tire shop says.  The VCS light is on, but no engine lights.  The O/D light works when I turn the O/D off, but I'm leaving it on for now.  I'm planning on getting the oil changed to full synthetic, and topping off the fluids, but no 'torque flush' on the transmission or anything.  I'd like to try and find out why the VCS light is on - I haven't seen anyone post on that yet.  The exhaust fix made the car quieter.  I will post back when I get the tires looked at and see how that helps the vibration.  I will also try the computer reset and see how that goes.  I'll also try putting premium gas, but will do this step last to eliminate variables.  Happy trails!