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SUVs Toyota Highlander Toyota Highlander Transmission Problems
226 messages, Last post on Nov 26, 2009 at 8:26 PM
You are in the Toyota Highlander Forum. Your Hosts are steve_ & tidester
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Replying to: minnesnowta1 (Oct 29, 2009 1:38 pm) I assume most of the "shuddering" complaints involve the V6 as I doubt that the I4 would even come close to delivering enough drive torque in 5th gear at 1500 RPM. An ATF drain and refill might involve a new fluid formualtion supplied directly from the factory. While a firmware revision would be the most obvious and expeditous corrective action that would likely impact FE adversely and that brings the EPA into the decision process. |
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| Apparently Ford experienced this very same problem involving real time control of ATF line pressure during the development of the Edge. Their solution was to adopt a variable displacement ATF pump. That way the pump could be "set" to a high volume, relatively speaking, at low engine RPMs, and a lower and lower volume as engine RPM rises. | |
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Replying to: wwest (Oct 30, 2009 8:45 am) |
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Replying to: wwest (Oct 30, 2009 8:45 am) Thanks all.
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Replying to: minnesnowta1 (Oct 30, 2009 10:17 am) |
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Replying to: wwest (Oct 30, 2009 8:45 am) finally got around to booking in my highlander with the dealer - only bought it two weeks ago. Of course they didn't have a clue, other than to suggest that the car is new with low miles (now 500) and that components need time to "bed-in" and computers need time to learn idle and shift patterns etc. I'm not sure if I have exactly the same problem as you guys, but to be honest - unless I'm imagining it, the problem does appear to be getting better !!. Last night and today I drove it around and couldn't get it to mis-behave at all. Previously I could do it pretty much on demand - 30mph, 1300-1500rpm, 4th or 5th gear, light throttle, throw in some hill/incline and there would be a pattern of pulses/vibration, always the same frequency, about 5/second or thereabouts, even my wife noticed it. A slight prod on the throttle and revs rise and the problem goes away. Could I reproduce it for the dealer? sods law applies and it wouldn't misbehave at all, I then took it for a long'ish drive and only once during the journey did I detect the faint patter of pulses, but it seemed to me to be much weaker and definately harder to reproduce now. Having said that it was dry today and previously it has been pissing it down for the last week - maybe that's a factor - I don't know, could be something to do with tires, grip, moisture in the air - dunno. I'm not sure that I agree with the low pressure ATF pressure line theory for several reasons (I could be wrong of course and will hold my hand up if that's the case) 1) If the problem is a design problem and first started in '98 I cannot believe that Toyota would have ignored it for so long, given the rate they turn out new engines, technology, transmissions etc. they could have fixed this - if Ford could do it.... 2) Toyota use this engine/transmission (3.5V6/5sp auto) in so many vehicles - highlander, rav4, sienna, camry... as well as a load of Lexus products, that we would have heard about design problems in bigger numbers by now and toyota dealers would be aware of the solution even if there was no recall - if it was as simple as just using a different type of AT fluid, it would be simple to fix and they would issue a technical bulletin for dealers and we wouldn't be getting the problem with new cars 3) In my case the patter/vibration occurs only on a very light throttle, not usually the sort of conditions that cause an engine to struggle. Personally (and I'm prepared to stand corrected on this by anyone who does come up with a definitive solution) is that it's down to computer learning, e.g. the computer controlling the transmission learning when to change to lower gears etc. This might well explain why I and the others here have only noticed it with low mileage '09 models. Interestingly enough I noticed that shifting the tranny into sport mode does alter the shift points e.g. a slight tap on the throttle sees the transmission kick down more readily (don't think I'm imaginging this - am I?) which would kinda indicate that it's not the line pressure but the computer (???). I would love to hear what happens when they change the tranny fluid - if it makes any difference - as usual - please keep us posted |
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",,cannot believe that Toyota would have ignored it for so long.." They haven't, by my count there have been at least 4 attempts at fixing this problem. Everyone knows, I hope, about the premature transaxle failures for the '99 and early '00 RX300's that were a direct result of the design flaw. With those models the ATF line pressure was kept as low as seemingly possible in order to extend the ATF pump efficiency and thereby the FE rating. That resulted in early failure of the transaxle clutches due to not having enough line pressure available in a timely fashion to accomplish two shifts, with the engine at idle or nearly so, in quick sucession. For the late '00 and on RX300 series the "fix" seemingly involved keeping the line pressure elevated above what was previously ('99 & early '00) considered optimal. It appears that fix resulted in localized overheating of the ATF even though the towing parkage, external ATF cooler, was made "standard". Even so the revised ATF drain and flush of every 15,000 miles was instituted. Justifiably so, it now seems. With the introduction of the RX330 DBW was adopted for a myriad of reasons but primarily to "protect the drive train". Delay the onset of rising engine torque, REGARDLESS of gas pedal pressure, until the appropriate downshift could be fully completed. Again, as we all should already know, that fix led to yet another symptom, somewhat hazardous symptom in ceratin situations. Re-acceleration downshift delay/hesitation of as much as 2 seconds. Next (~'08..??) came the firmware revision "fix". Watch the driver's actions with/on the gas pedal in order to prevent an inappropriate upshift when/if a following downshift is easily predictable. A fast and quick release of gas pedal pressure would likely mean the driver's "real" intent is to coast down to a lower speed. Whereas a slow and easy release of pressure on the gas pedal would/might mean that the driver intents to simply begin cruising along at the current speed. |
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| Even in the US the NIH (Not Invented Here) factor is often enough to prevent adopting of a new idea,GOOD ideas, thought up elsewhere. In the "heads down" Japanese culture that will be true in spades. | |
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Replying to: wwest (Oct 30, 2009 8:04 pm) I bought an '09 Sport/AWD HL in June. I experienced the same shutters/vibrations that all of you have described. For me, they only showed their face while around 30-40 mph range (typically when on exit/entrance ramps, when first starting out on the road). However, I now have just over 4,100 miles on it and do not experience them at all. I'm convinced that the parts have been broken in and worn to the viscosity of the transmission fluid. I haven't felt these problems for roughly 800-1000 miles. I've kept reading on this topic and look forward to what others find out with the dealer, and I finally created an account so that I could give other owners the peace of mind that it may actually subside. Like a couple others have said, everything is so perfect and smooth on the HL that you really notice something like this. -Steve Oh and also, my HL takes a few seconds to downshift while decelerating and it "releases" like it's shifting into neutral and freewheeling when approaching a stop light. Does anyone else notice/experience this? It's not dangerous, just not smooth. |
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Replying to: mccartsj (Oct 31, 2009 9:06 pm) You're describing the coastdown fuel technique used to extend FE. During throttle closed coastdowns the fuel is cut completely and the transaxle is downshifted in accordance with decaying roadspeed in order to prevent an engine stall. Then at a certain point ~15-10mph, fuel flow MUST be restored and the transaxle is upshifted accordingly. The driver then "feels" a slight surge forward. Feels as if the brakes were slightly released if they are being used. Your HL will not subsequently downshift into first gear unless/until you come to a full and complete stop or decide to accelerate again.
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