jaswood

What is it that makes you think the ABS has a problem? ABS activates ONLY if the wheel rotational rate is declining so rapidly that lockup is eminent, too rapidly for road/speed conditions. You may simply have marginal braking at the front.

Was checking on scheduled maintenance and saw your post. Does this actually mean the tranny fluid NEVER has to be replaced???? That's certainly what my 2001 RX300 owners manual implies.

It's definitely the caliper bolt washer. It fits in a slightly recessed part of the caliper where the bolt goes in and there's another for the other bolt. Apparently, it popped out of its recess when I moved the caliper. As it turns out, I forgot to put it back. Begs the question... Why would you remove the caliper mount, torque plate, just to change the pads...?

It's definitely the caliper bolt washer. It fits in a slightly recessed part of the caliper where the bolt goes in and there's another for the other bolt. Apparently, it popped out of its recess when I moved the caliper. As it turns out, I forgot to put it back. It makes no sense to have (soft) copper washers under a caliper mounting bolt that MUST be torque to a fairly high specification. Perhaps someone used the wrong waskers in the past..? I don't have access to my '92 LS factory repair manuals at the moment but I do have the ones for the 2000 RX300. All four caliper "mounts" use shoulder bolts. IMMHO it is unusual to have washers of any kind with shoulder bolts.

After about 250K miles the weak point in our '95 LS proved to be the rear diff'l mount/cushions. Too much rotational free play resulted transmssion hunting at ~40-50 MPH.

That's looks VERY suspiciously like a crush washer for the engine oil drain plug, in which case it should NEVER be used otherwise.

Sorry, I find it a bit hard to accept that a defective MAIN O2 sensor in an engine with TWO sensors, would result in a lean misfire. Over the years I have been reponsable for the care and maintenance of a '90 LS (a Bill Gate's trade-in), a '91 LS, 3 '92's and a '95. The '90 and one of the '92's are now off the list. Amongst that group, all now pushing close too or over 200K, I have encountered numerous instances of O2 failures. ALL have result in a CEL but NONE exhibited any physical indication of fault. I assumed that once the ECU detected that one of the sensors was faulty it simply relied on the opposite for fuel trim corrections/adjustment. Why, if you think it through, should it be otherwise. I suspect you cleaned, as anyone would, the MAF/IAT sensors at the same time, more likely the actual "misfire" cause, as installing the O2 sensor. Yes before changing the O2 sensor, The MAF/IAT sensors had been cleaned AND even changed without any improvement One more thing I want to mention is that the O2 sensor was completely dead (no reading for any resistance) I knew that this sensor was faulty (I had a CEL) but I could not imagine that this is the reason of misfire, that's why I left it to be the last option The 2 wires leading to the sensor element will always read open. The only way I know to test those is to heat the element in our oxygen rich atmosphere and test for the output voltage to be in the proper range. It appears that if you had "read" the actual code it would indicated an open O2 sensor HEATER, not the sensor itsself. the heater is only used during initial engine start up. Once the exhaust is supplying HEAT the sensor will provide good outputs.

The Trac and VSC codes are basically meaningless, they show a fault only because they are DISABLED whenever there is a CEL. CEL's are most often caused by a fuel cap leak, cap not fully seated, or if you happened to remove the fuel cap but did not add fuel or didn't add enough fuel for the emissions ECU to register/detect. A CEL caused by a fuel system leak, as above, will clear itself within 3-4 drive cycles. Read the actual code (Autozone, etc.) and if it is the fuel cap then ignore it for a few days or have it reset.

Sorry, I find it a bit hard to accept that a defective MAIN O2 sensor in an engine with TWO sensors, would result in a lean misfire. Over the years I have been reponsable for the care and maintenance of a '90 LS (a Bill Gate's trade-in), a '91 LS, 3 '92's and a '95. The '90 and one of the '92's are now off the list. Amongst that group, all now pushing close too or over 200K, I have encountered numerous instances of O2 failures. ALL have result in a CEL but NONE exhibited any physical indication of fault. I assumed that once the ECU detected that one of the sensors was faulty it simply relied on the opposite for fuel trim corrections/adjustment. Why, if you think it through, should it be otherwise. I suspect you cleaned, as anyone would, the MAF/IAT sensors at the same time, more likely the actual "misfire" cause, as installing the O2 sensor.

First, a word about that latter, last, link. The O2 heater resistance quoted as being required is quite a bit out of range with the actual factory shop/repair manual specification. For myself I would accept that any heater resistance up to 18 ohms would suffice. And be aware that exposing a perfectly good, even brand new, O2 sensor to our oxygen rich atmosphere while the sensor element remains heated will/might "spoil" the sensor, cause a CEL, for the first 100-200 miles. I had suspected such for quite some time and just recently tested the theory by heating a new sensor on an electric stove element. I took several days before reseting the CEL "took". That's also why a crack in the exhaust, even downstream of the O2 sensor element, will result in a CEL, oxygen can get to the sensor before it has time to cool.

To "read" any non-EPA mandated emissions codes you must jumper 2 pins on the OBDII connector and watch the flashing of the "failure" indicator to discern the code.

Why don't we agree to call the described symptom as engine "tugging" rather than "misfire" which could be misleading. Tugging can be the result of ignition, EFI, fuel pump pressure, and even the secondary "Trac" engine de-throttling servo. If it happens mainly with acceleration, even slight acceleration, you may have a plugged catalytic converter. Also, a loose motor mount, or rear diff'l mount, might result in a tugging feel due to the resulting "in and out" action of the lockup clutch, at those speeds. That was EXACTLY the complaint, tugging between 30-40 MPH, the most often driver of our '95 LS400 had. Replaced the rear differential's front mounting cushion to clear up the problem. The 2 rear diff'l mounts are still in the freezer awaiting a nicer day. The frustrating thing about the diff'l mount failure symptom is that there was no CEL at all.

Check the operation of the radiator cooling fan(s) FIRST. Not just for flat out failure, may be intermittent due to wear of the commutator brushes. Oops, almost forgot to mention. The engine block cooling fluid temperature sensor seems to be highly prone to failure.

With the advent of full adoption of OBDII jumpering the 2 pins in the OBDII connector does not "flash" the CEL to determine the fault, you need a reader for that. At least that seems to be the way in both my '95 LS and '01 RX. Jumpering will still "flash" the non-EPA mandated emissions functions, ABS, VSC, etc.

Your hwy cruising FE will not be much different than the standard RX. The BEST FE, in comparison, will always be in city stop and go circumstance. During the winter the RXh FE advantage declines substandually. Need to heat YOU and the catalyst, lower regen capability pre-emptively when the traction is marginal or if the OAT is near freezing or sub-freezing.

Other considerations... Wintertime FE gains of the RXh vs RX450 can be pretty poor in comparison to summertime use. The need for ICE running for heating YOU and the catalyst, regen system compromised by slippery conditions and in sub-freezing temperatures all add up. If left to it's own the RXh will probably run the A/C 24/7 making matters even worse. Luckily both the RX and RXh have the ability to over-ride the A/C use. Also, the FE advantage of the RXh virtually disappears for hwy cruising, real RXh FE gains are only for city stop and go driving wherein regen energy recovery yields a significant return.

One would think that since the RXh has no mechanical F/R connection, thereby no driveline windup issue, the RXh firmware rear drive coupling implementation would be a lot more "robust", higher and more consistent rear drive coupling. But with the RXh that's strictly a firmware implemetation issue, so who knows. I do know/think that if you could find a way to "simulate" front wheelspin/slip the rear drive would get coupled in pretty instantly. Where I in control of writing/composing the firmware specifications for the RXh's "F/awd" functionality the torque distribution would would be 50/50 F/R during straight ahead acceleration, linearly, incrementally, reduced to 0/100 as lateral, directional control, forces increase. 0/100 F/R for simply cruising along. So much for dreaming... On the other hand with the RX's F/awd system what you get in the latter instance is simultaneous INSTANT DBW engine dethrottling. Luckily you will have a Trac...VSC disable capability to use when the F/awd system fails your need. Personally I would go with the non-hybrid F/awd for my wife's wintertime driving safety. You could/can add a dual function switch to enable or disable the rear drive clutch "at will". There is absolutely no reason for continually stressing (over stressing??) the driveline on perfectly tractive surfaces as the system will do if left to itsself. So I would open the rear drive clutch circuit unless operating on a suspected or KNOWN low traction surface. Conversely when operating on a KNOWN low traction, slippery, surface, no issue of driveline windup, I would want the rear drive clutch continuously, FULLY, engaged. If I could find a rear diff'l ring and pinion that would fit and that had a slightlly different,"overdrive", ratio so much the better. In that case torque level distribution could be as high as 30/70 with the rear clutch fully engaged.

As a general rule rain, wet, does not result in "shorts" for 12 volt sources. Salt-water SOAKING, maybe. Thank you for the reminder. Yes, at that voltage, there is probably not enough electrolyte in rainwater to cause anything to short. Especially if the circuit is fuse protected. So yes, as a general rule, cars don't catch on fire for reasons like this. I would like to thank everyone for their input so far. Now, has anyone worked on the undercarriage of an early 2000s RX300? Yes, 2000 and 2001, 2001 still sitting outside in the driveway, but I don't remember seeing anything like your pictures. I'm going with some sort towing module.

As a general rule rain, wet, does not result in "shorts" for 12 volt sources. Salt-water SOAKING, maybe.

MN........ Have you considered the base model, V6, Porsche Cayenne...? The newer RXes, 2010 and beyond, have a muchly improved, BLACK vs WHITE, F/awd system as opposed to the totally non-functional system, Trac braking ONLY, in the RX330-350 through '09 MY. That being said the last I knew the ML had a definite rear biased AWD system which would be a significant improvement over the new RX system first used in the Ford Escape/Mariner series over 10 years ago now. The early RXes, '99-00, mostly functional F/awd system was discontinued by the '01 MY due to the persistency of premature transaxle failures arising from the overstressed, lack of robust design, driveline components.

Brake lights, brake light switch...always on...?

Absent a CEL I would suspect a failure of the catalytic converter's internal honeycomb structure. Falls apart, often, and intermittently, blocking exhaust flow. Idles okay, but any power level requiring high exhaust flow.... You get an intermittent CEL since the secondary, catalyst efficiency, O2 sensor goes out of range but only with a serious level of exhaust flow blockage. Glowing exhaust pipe/converter is sometimes a clue.

The metal to metal "clunk" you hear from the front going over a bump, speed bump, results from the coil spring having worn down, pushed through, the upper rubber mount. I used rubber hose pushed over the top coil of the coil spring rather than pay Lexus price for new mounts.

Since about 2000 the engine control ECU has had the ability to adjust the fuel mixture via EFI dutycycle to combat/alleviate problems resulting from low octane fuel in a high compression engine.

"...They're hidden behind...." But not hidden from MY mind's eye... The Relentless Pursuit of PERFECTION.