wwest

My best guess would be that the viscous fluid in the clutch/coupling is, for want of a better word, congealing, over time, distance, and heat cycling.

For some reason the ECU that monitors the brake light filament "thinks" the brake pedal is always depressed, so it is continously checking for filament current flow. When the brakes are actually applied it "sees" current flow and that makes it "happy".

I have noticed a trend indicating that many posters believe that the premature transaxle failures some (many?)(a few?) are having in the RX300 only pertains to the AWD version. With no opinion one way or another myself I did get to thinking about just what might be different in the AWD version that might cause the transaxle itself to fail. Last winter my daughter and family went snow skiing in their AWD Chrysler T&C. They had a full set of summer wheels/tires and winter wheels/tires. The winter tires were on the OEM wheels and the smmmer tires, Bridgestone Turanzas were on 16" plus size wheels, correctly sized. But my son-in-law only put the winter tires on the front since that would save time and the snow chains would fit. They got about 50 miles before the PTO section of the transaxle failed. Apparently the slightly disparate tire sizes front vs rear had caused a severe overheating of the PTO. Given my own experience with the RX300 viscous clutch always remaining so flaccid it cannot drive the rear wheels it was initially hard for me to believe that was what had happened. The Chrysler VC had worked so well that the drive train had overheated and failed. Some of you may remember that when I first purchased my 2001 AWD RX300 I quickly became suspicious that the rear wheels were not being driven. I did some shade tree testing that determined to my our personal satisfaction that the rear wheels were not recieving any substantial level of engine torque. But several posters here questioned the validity of my shade tree testing so I took the RX to be tested on a 4 wheel dynamometer. That testing verified that the engine torque to the rear was initially about 10% and only after minutes of disparate F/R loading did the ratio rise to something like 75/25 F/R. Today, just moments ago, I repeated my shade tree test procedure. With all four wheels well off the ground, engine running and in drive I first verified at idle that I could stop any one wheel from rotating with light hand pressure. Then I verified that I could stop both rear wheels without affecting the rotation rate of the front. Next I blocked each rear wheel with a piece of light pine 1x2". Just a light touch of the gas pedal resulted in an immediate breakage of the 1x2". That is NOT what happened 4 years and 50,000 miles ago. At ~2000 RPM engine speed all I could get from the 1x2's at the rear was some creaking. My guess, now, is that the reason my ATF looked and smelled burnt at 40,000 miles is because the viscous fluid has congealed for some reason and now the center diff'l is always "locked" by some very high percentage. That would undoubtedly result overheating of the PTO lubrication and most probably the ATF just behind the shared "wall". Is this why the RX300 transaxles are failing prematurely??

That's undoubtedly your VSC system activating, it thinks your RX is not following the path set by the position of the stearing wheel. Could be a real, justified activation, or your yaw sensor or stearing wheel position sensor may be intermittently defective.

If you spend some time in Japan you will discover that this is NOT outside the norm there.

In researching details of Lexus new DIS, Direct Injection System, I came across several articles indicating Lexus is dropping ALL FWD models from the line-up. Apparently the IS series is set to replace the ES and the FWD version of the RX series will be dropped. RWD and/or AWD only from this point forward. Lexus Canada no longer sells the FWD version of the RX.

OAT..Outside Air Temperature. I can't verify this but I have heard that the A/C compressor uses up to 1/3 of the engine HP at cruise speeds. Some posters have reported a 10% improvement in MPG, 22 to 24+. And yes, today's A/C systems are outstandingly efficient. But not when used in the way they are in these automatic climate control systems. In these systems ALL of the airflow is first routed through the A/C cooling evaporator which is kept as close to 32F as is possible. In order not to discomfort you with such COLD airflow a portion of the chilled air is then routed through the heater. The two portions are then remixed to achieve a reasonable comfort level of airflow to your face and upper body via the dash outlets. Sort of equivelent to using your furnace at home to reheat the cooled A/C output. Running the A/C when the OAT is below 65F only benefits you if you have need of the dehumidification aspects of its operation.

You can easily modify the MAF/IAT module's IAT, intake air temperature, signal so the mixture runs to the lean side during acceleration. But during cruise, relatively constant speed, the front oxgen sensor determines (primarily) the proper A/F mixture ratio and I don't know of any easy way to defeat that. Prior to the C-best ability becoming available for me to manually disable the A/C indefinitely I always disconnected the A/C compressor clutch during the winter months, otherwise most modern day vehicles with automatic climate control run the A/C all the time. With the c-best option I typically disable the A/C if the OAT is consistently below 65F. Don't know just how much this helps MPG ratings.

And MY point was/is that if you drain 5 quarts there is very little, or NO ATF left in the torque converter! I don't pretend to know why this is the case, previously I always had to remove a drain plug in the torque (Ford) converter to be sure of draining all of the ATF. Have torque converters become a LOT smaller with the advent of the more precision CNC machining of the turbine blades, etc, and use of lockup clutches? The space "allocated" for the torque converter in my 01 RX isn't nearly the size of the one in my 84 T-bird.

My 2001 AWD RX300's transaxle hasn't yet failed but I will say I have very little doubt that it will fail before I get to 100,000 miles. A vehicle that doesn't require any ATF maintainance procedures for the life of the vehicle to have burnt ATF fluid at 40,000 something is very WRONG. IMMHO were Toyota a truly honest and forthwright company they would have long ago stepped up to the plate and notified owners of the problem and the need to modify the transaxle maintenance procedures. Even better would be to agree to cover the cost of unexpected ATF drain and fill.

Okay, rlin78, so I wasn't explicit enough. What I meant to say was more than 5 quarts of fluid THAT REMAINED WITHIN THE TRANSAXLE and did not indicate an overfill. Using your method some one could readily "add" 100 quarts.

Why do you care? They can't be used without the low beams which makes them virtually useless anyway.

That K&N "mod" will quickly result in an MAF/IAT sensor failure ($167 DIY) due to oil and dirt contamination. Oil wicked from the K&N filter, and dirt because the K&N is a lot less efficient, 100% of the time, at cleaning the incoming air than is the OEM filter. And just how often at you are WOT and max engine RPM? That's the only situation in which the OEM filter provides the 3-5% restriction in airflow that the K&N might not. Racing teams use K&N, first, because they are PAID to do so, and secondarily because a LOT of time is spent at the top end of engine performance and racing engines are only expected to last maybe 2 or 3 races, not the 150-200,000 miles most of us expect out of todays vehicle engines.

First, if anyone out there can find a way to cram more than 5 quarts of ATF into an AWD RX300 or RX330 without the dip stick indicating an overfilled condition I will pay them $1000. At ~40,000 miles I drained and refilled my transaxle using 4 quarts of ATF purchased at Lexus of Bellevue. A few weeks later I noticed that my ATF was looking brownish again. Here on the internet I learned that the 5th quart is trapped in the diff'l and must be drained via a separate drain plug. So, drain and refill again but this time it took five quarts and now at 50,000 miles my ATF is still pinkish. If a single dirty quart inadvertantly left in the diff'l can contaminate the 4 new quarts to the level I experienced that why has not the 9 quarts I couldn't drain contaminated the new 5 quart ATF refill? It takes 16 quarts to FLUSH the transaxle, not to fill to capacity. How many quarts of brake fluid does it take to flush long enough to be sure ALL of the "contaminated" brake fluid is gone? Infinite # of quarts.

Draining and refilling the ATF on a regular basis will NOT prevent these premature failures, it will only delay them. Personally I would not recommend anyone bother to drain and refill until and unless the ATF begins to appear brownish, burnt, and/or smells burnt. My 2001 AWD RX300 came with an external ATF cooler as a part of the tow package and you might note that there is a diagnostic indication on the dash that lights up if the ATF begins to overheat. My indicator has never come on and the towing capability has never been used yet my ATF was looking and smelling burnt at only 40,000 miles. I firmly believe that these premature transaxle failures are the result of a poor firmware design embedded within the engine/transaxle ECU to increase fuel economy, reduce emissions, and reduce the potential for loss of directional control in a FWD or front biased AWD vehicle during coastdown situations on a slippery roadbed surface. ABS will do a very fine job of keeping your front wheels rotating during actual braking, even light braking if the surface is slippery enough. But what's to keep those wheels rotating if the transaxle drops into 1st gear in that very same circumstance? You may notice that prior to 04 (RX series) the transaxle would upshift just before coming to a full stop and then only downshift into 1st gear if/when the vehicle comes to a full and complete stop. This, upshifting, also happens at road speed if you fully release the gas pedal. So, what do you suppose happens if I decide not to come to a full and complete stop and want to accelerate quickly and/or rapidly while that transaxle is in an inappropreate HIGH gear? The transaxle clutches SLIP for a few hundred milliseconds, that's what! For 04 and later Lexus simply uses the new e-throttle system to prevent the engine from developing torque until the transaxle has time to downshift into the most appropreate gear given the position of the gas pedal. So, no more premature transaxle failures due to clutch frictional surface wear. And what does it matter to Toyota or Lexus if not just a few people are injuried or even killed due to accidents arising from a 1 or 2 second engine torque delay. All they will say is "prove it to the judge!".

Yes, the are airflow "exhaust" ducts under the front seats to route heated airflow to the rear of the car. Like the dash vs footwell in the front the outlets under the front seats are primarily used for heating mode and the console outlets for cooling mode. Because of the way the airflow in the A/C & heat plenum is routed it is very difficult to get heated airflow to/from any of the "cooling" outlets. Regretably this also includes the windshield defrost/defog/demist airflow outlets. The only reliable way to get warming airflow to the interior surface of the windshield is in the dedicated mode wherein that becomes the ONLY outlet airflow path.

First, the entire climate control output airflow system is specifically designed such that it is practically impossible to get warming airflow from the upper airflow outlets, especially once the cabin atmosphere has reached or neared the temperature setpoint. I believe that Denso US (NipponDenso Japan) even has US patents on this design concept. It is not at all unusual for the dash outlets, and windshield frost/defog/demist outlet airflow to be as much as 20F COOLER than footwell flow in otherwise same circumstances. I don't know if you have really checked but I think you will find that the front/rear airflow distribution is much more even in heating mode than in cooling mode, provided you close the manually operated dash outlets as I stated before. I suspect that the lack of equal cooling airflow to the rear is the result of an intentional design bias since the rear windows all have a reflective coating to prevent radiant heating whereas the front does not. And part of what you are "fighting" is Lexus' "Pursuit or Perfection". In this case overall quietness of the cabin environment. The entire mold and mildew problem and the instances of sudden windshield fogging all arise from the fact that these vehicles are very well insulated and sealed to prevent wind and road noise. Obviously that also results in very little "flow-through" to keep the cabin atmosphere freshened and from that we sometimes get a dramatic level of mold and mildew spores breeding in the A/C plenum due to the level of moisture often trapped there after a period of A/C operation and of course that also often leads to the many episodes of sudden and instant windshield fogging.

Two solutions. First, the automatic climate control remains in cooling mode when it really shouldn't. Lexus hasn't discovered, nor explored, any way to determine when there is a lack of radiant heating available from the surrounding landscape. As a result the system remains in cooling mode even on the coldest darkest night when the radiant contribution to your human metabolism is clearly negative. So, rather than endure the discomfort of cool and dry airflow to the face and upper body of you and your passengers you might want to become more diligent about manually switching these systems into heating mode, footwell airflow(***) in these circumstances. That will result in WARM airflow from the footwell, front and rear. You might also note that the two dash airflow outlets near the front side windows are not automatically operated and will need to be closed manually if good heating airflow coverage is desired. *** In cooling mode absolutely NO warming airflow is routed to the windshield. On a rather cold or even cool day that might result in a thoroughly CHILLED interior windshield surface due to impinging COLD airflow due to road speed. When the A/C is automatically disabled at ~35F, or otherwise becomes disfunctional due to climatic conditions, you might be subject to sudden windshield fogging. So rather than waiting for the system (05 and later) to automatically switch to the windshield warming mode just as the windshield fogging problem is most likely to occur, you might want to pre-empt the system by switching into footwell (some "leakage" to the windshield) mode as the temperature declines below 55F and there is a definite lack of radiant heating effect, then into footwell and windshield combined mode at about 45F.

Not so sure about ATF drain and refill. Not saying that it isn't a good idea, at least if you check the ATF on a regular basis and change it out only when it starts to look and smell burnt. The Lexus RX series has an ATF overtemp diagnostic indication light in the instrument cluster. My AWD RX300 has the tow package, including an external ATF cooler, has NEVER towed anything, and yet the ATF was smelling and looking burnt at only 40,000 miles. It is my opinion that nothing you do will prevent these transaxles from failing "prematurely". Other than some internal preventative maintainance. Like replaceing all the clutch friction surfaces every 50,000 miles. Replacing the ATF when needed will only delay the premature failures.

Those are probably the ones using the non-functional filters, K&N and such.

The heater core is "downstream" of the A/C evaporator and so heating the airflow will have no effect unless you are in recirculate.

First....!!!!...STOP!!!! Never, NEVER run your car with the battery disconnected. The battery is an integral part of the time constant of/for the voltage regulator. Without the battery you will get HIGH voltage spikes out of the alternator and those spikes can very likely do permanent damage to the various electronic modules, ECU's etc, in the car. Second, the actual core problem for a 93 LS is most likely that the slip rings are worn clear down to the steel alternator shaft. That's what I found on my 92 LS just months ago at ~100k miles. Apparently the slip rings are made of really soft copper as my slip ring brushes had lots of mileage left. Since it is such a very RARE thing for the slip rings to wear out before the brushes themselves your alternator repairman may have never suspected/checked those. As for myself I went to Lexus and bought new brushes before I even removed and opened the alternator since my lifelong experience is that the brushes will wear first.

sicklingly sweet odor is almost always anti-freeze.

Be aware that many manufacturers have switched to carbon fiber lockup clutch frictional surfaces and additives previously used in ATF should/can no longer be used.

First, the 92 did not have a pollen filter so don't bother looking. Second, the 92 came from the factory with a porus nylon coating on the A/C evaporator into which was embedded an anti-bacterial chemical so that mold and mildew spores did not breed in the dark, dank, and moisture environment of the A/C plenum. The problem was, is, that once the chemical leached out of the evaporator vane surfaces it then formed a virtually perfect habitat for those very same spores. What I would do is put a battery charger on the battery, lower the rear windows and turn on the ignition and run the A/C blower continously for several night while exhausting 2 or 3 cans, intermittently, of lysol disinfectant spray over that same period of time. Thereafter avoid, absolutely, the operation of the A/C except in times that it is actually needed for cooling. I disconnect the A/C compressor clutch connection in mine during the winter months. It also doesn't hurt to remember to lower the windows slightly in the garage at night for several days after the A/C is used, or during its summer use. Now go to: http://www.airsept.com And read about their EED, Electronic Evaporator Dryer device. Also be fully aware that this particular vehicle is VERY subject to sudden and unexpected windshield fogging due to a design flaw within the climate control system. Even if/when the indicator is on for FRESH incoming airflow that system may actually be predominatly in recirculate. Lexus tells me that the only way to be certain that the fresh mode is being used is to take the incoming airflow selection out of automatic mode by manually selecting fresh mode by depressing the rocker switch in that direction. If your windshield should begin to fog over, even in the slightest, DO NOT select the defrost/defog/demist mode before turning the temperature setpoint to MAX HEAT. Most early Lexus climate control systems rely EXCLUSIVELY on the A/C to defog the windshield. The A/C's ability to perform that task is dependent on external atmospheric conditions. Below about 45F this ability declines rapidly until at about 35F it is non-existent.