cachaciero

The theory is fine however try to apply it consistently on the M25 / M4 🙂

Bit late to this topic and what I will have to say is based upon my experience with an RX400H. IMHO the bit that needs re-mapping is the gearbox / electric motor controller. The 450 motor is unlike the 400 already tuned for economy, now given that on a reasonably cross country run mixed motorway / A roads I can see 32- 34 I would have thought that the 450 would be able to get 35-38 on the same journey and maybe better driven to the cars strengths. However the bit that will kill the mpg figures on the 400 is Mway driving, the fuel consumption drops of a cliff at about 65 and driven hard will soon dip to sub 30mpg, I don't understand why the cut off point is as marked as it is, drag force will increase in proportion to the square of the speed so I have to assume that being a draggy square box the extra 5mph between 65 and 70mph is enough to significantly increase the aerodynamic load at that point. However there is one other issue that takes its toll on motorway driving. Imagine driving in a file of cars all doing nominally 70 but slowing up to say 60 and then accelerating back to 70 and then decelerating again (M25 scenario )- Now my 400 decelerating from 70 will often require a touch of brake to get the speed down to an acceptable level in the distance available under these circumstances I will often put it into B mode thus increasing the deceleration and getting a little extra into the battery, as the stream speeds up back into D and touch the throttle, now I don't require much energy to get back to 70, the battery is well up and there is more than adequate electrical energy available to restore speed but the moment you touch the pedal the IC engine springs into life, burning petrol which does not need to be burnt, because a minute or two later you are having to slow again and this really pi???? me off. That is the one area where my gut feel is that the software really needs a bit of re-working. There appears to be little sensible relation between speed, torque demand (pedal position) and battery power' Unfortunately with no access to logic flow diagrams let alone source code it is near impossible to do anything. Someone with the requisite tools and knowledge could probably re-constitute the code but that would require a lot of enthusiasm or money and as we are not talking about races to win on a low volume production vehicle there is little chance of either happening as far as I can see.

As far as I can see the GS450H is in terms of drive train / HV battery is little different to any other Toyota / Lexus Hybrid and overall HV battery failure is very low so what is different about the GS450H? what is "a high number of people with battery issues" ?. I suspect that at a battery module level the modules are identical over the whole Hybrid spectrum, the only thing that appears to change is the number of modules in a battery pack and hence the final voltage. When I purchased my first Hybrid a Prius 2 battery and ability to repair / replace was a concern and I did a fair amount of research on this and came to the conclusion that it was no big deal to repair a HV battery pack, I believe pretty well any second hand HV battery should be a source of usable individual modules, Toyota seems to like to keep things standard across models and generations as far as possible and I believe that this will apply to batteries as anything else, however this is unproven and I would be interested if anybody knows for fact that this is not so. The only problem I can see with building / refurbing an HV battery pack is charging it on the bench and ensuring that all the modules are at a similar charge state before use this is improtant. In the event until now I have had no reason to explore this scenario further both the Prius and Lexus just work and the occasional check with an analyser would indicate that there is little deterioration from new in the individual battery modules on either car. NiCad batteries providing that the charge / discharge regime is controlled within limits are virtually indestructible, in this respect the Toyota setup does control the battery charge / discharge regime very conservatively, actually too conservatively IMHO. 12 V battery is another story :-) Friday at 09:44 AM 19 replies

Have a trawl through e-bay though knowing what the OEM part number was would help.

Thanks for that and the reference to Toyodiy some interesting reading there. Rgds Tony

Does no one know the answer... ?

O.K it doesn't work the way I believed it did, have to say I am a little surprised, it aint logical :-). The next question is what are the o/p volts 12V....5v or something else and what is the switch? straight forward electrical contacts which may handle enough current to drive a relay or an optical or other semiconductor O/P which may have very limited current drive capacity, hooking a relay coil straight onto such an output could have disastrous consequences. Bit more info required :-) Regards Tony.

Please! Please! don't ever think I have superior knowledge on anything and least of all the Lexus which I have only had for six months :-) I don't even have a complete set of schematics and none of the Training Material which I am sure is available to their Techs. Currently for areas of interest I have to go onto the Lexus Support site and wade through bits of that trying to find info on the things which are of interest. So far I have not had a need to look in detail at the gear selection side so I don't have all the info on this area of the car. As regards the gear selector something I saw / read somewhere makes me believe that it works the way I said it does BUT I could be wrong. The gear positions are displayed on the instrument panel and for sure that data comes from the network, doesn't mean to say though that there isn't a discrete wire for each position directly from the gear switch though I can't see why they would need to do that. If you like send me a copy of the schematics you have (saves me time and money!) and I will have a look and tell you what I think. However my gut feel is that is that it will be easier to purchase one of the available decoder boxes that hook onto the can bus and give the discreet outputs you require, prices seem to range from about 50 to 150.00 depending on the number of outputs. Out of curiosity why don't you just use the switch to disable the front sensors? regards Tony

A relay connected to D ...(rive?) you might have a problem doing that I would have to go back and delve into ,the wiring but pretty sure that the Gear Selector is it's own ECU connected to the CAN bus so there will not be anything to connect to :-). Tonyd

Indeed :-) Unfortunately this site does not appear to e-mail me reliably with updates

Could not agree more, the only car black is good for is a Hearse the occupant being long past caring about being kept in an oven. Tonyd

My personal view about Hammerite is not very positive, never had much luck with it, yes you can paint it over rust but then you can paint lots of things over rust, the biq question is how well does it contain it? in my experience not very well. There are better and more long lasting solutions to rust. My preferred technique is to mechanically remove as much rust as possible then wash with water containing a salt neutraliser. Then paint / spray a conversion coat, the kind that goes blue/black when it's dried, finish with a coat of epoxy primer they are not so difficult to work with as you might think, it sticks like the proverbial even to poorly prepared areas and once cured is hard and totally air and water proof. More complicated than going down to Halfrauds and buying Hammerite of the shelf but a much better job and you won't have to do it again in a year or so. Your initial outlay in material will be more expensive but the materials do not markedly deteriorate with time and the next time you find a bit of rust you will have everything to hand.:-) For anybody working on cars dealing with rust cure / protection I would strongly suggest a visit to www.rust.co.uk their online site and printed catalogue is informative and they can supply all the products I have referenced. I have no connection with them other than as a satisfied customer. Fe-123 from the same company may also be worth considering if mechanical cleaning is difficult due to access. Tonyd

That is exactly what I meant, find it very annoying to find a thread that touches on a problem I have and then it just ends with no conclusion, was the problem fixed? what fixed it? or did it just disappear as sometimes happens. Tonyd

Ah! This was a "research" exercise when looking into fitting after market sensors. The vast majority of cheap and cheerful after market sensors just look at the reverse light line, and have a manual switch to control the front sensors. Now for me that really was a cowboy approach (but cheap :-) I knew that all the data one could possibly need would be available on the CAN system if one could access it. Further investigation revealed that there are available decoder boxes which connect onto the CAN bus and process the data giving discreet output lines for Reverse, Parking Brakes set and a <5mph Flag. With such a box one could choose whatever combination of conditions to activate the sensors, my choice would be all sensors on below 5mph and OFF when Handbrake set and forget about the reverse condition. However the cost of such a box was in the order of a 120 quid which I decided was a bit much for a 10 yr old car so when I found a set of sensors that activate the rear and two front corners in reverse and the fronts for 30 seconds after coming out of reverse I decided that that was a reasonable compromise, so in answer to your question I do not have any schematics :-( The Lexia TPA800 does not connect to the CAN bus so does not have access to the data which is available on it. The TPA800 connects to a speed signal which is a pulse signal proportional to speed used by the GPS amongst other things, and the reverse light switch. (At the time of my previous comment I had not looked in detail at how the TPA800 connects I assumed that given the price Lexus would have done the job properly...silly me.) Now I deduce from that, that within the TPA800 there is some computation of the speed signal and I would expect this to be able to work on the basis of activating the sensors when the speed is below a certain threshold and deactivating them at zero, however that is a guess on my part. The speed pulse signal is I believe derived from the wheel speed sensors on the AntiSkid system so if my guess on how the TPA800 works is true then maybe if there was a noisy sensor such that at zero wheel rotation it was generating enough noise to correspond to say 1mph then the parking sensors may not turn off, just a theory. tonyd

Simple question are there any problems fitting a set of RX300 wheels on a RX400h, both sets of wheels look near identical but just because they look the same doesn't mean that they are :-(.

A valiant defence but... lets see 2001 Citroen C5 Exclusive which means that it's design date would be circa 1998-2000. Basic Spec as follows as I recall. Automatically heated and folding mirrors. Automatic wipers integrated with window / roof control Automatic Climate control, Automatic Headlights One switch control for roof open /tilt Xenon lights. Self levelling suspension that dynamically changed the car attitude to maximise stability / economy at speed. Selectable Sport mode. Noise reducing glass. Auto box with manual tiptronic type option. Body shell galvanised prior to paint. (Not sure if Lexus did that but my feeling is not don't want to scratch the paint to find out :-) Leather Heated Seats were an option. Oh! and the alloy wheels never ever flaked paint :-) Now PSA were not worried about Japanese competition but German Competition so I assume that the likes of BMW Merceds Audi etc. were in the late ninties of similar specs which means that by 2005 Lexus / Toyota should have been much further advanced than they were.

Once bitten twice shy :-) Your experience is sad to say not uncommon :-( IMO the biggest reason for unreliability in PSA products is the repair network often staffed by people that really don't know how their cars work and often it seems don't care. PSA and particularly Citroen have always been technically very advanced but that brings a requirement for a knowledgeable support base which in turn brings extra cost in terms both of personnel quality and training costs objectives which most repairers are unprepared to meet. It does seem to me that these days most cars out of the factory are pretty good and reliable, the problems start when a small problem is given to a repairer who then turns what is a little problem into a big one simply because in many cases he doesn't know WTF he's doing, doesn't have the appropriate diagnostic kit (Essential these days) or anybody who knows how to drive it and interpret the results correctly. The saving grace for me in owning an early C5 in Exclusive trim was that by training I am a systems engineer and I acquired a load of Citroen Training manuals which really explained how the car worked (warts 'n all) with that and a Lexia I could diagnose a problem go to a garage if i did not want to do the work myself and say "change that bit" and that bit only. I don't have that type of info for the Lexus and it makes me feel a little "naked".

Big problem with autogearbox in many cases are the magic words "sealed for life" oil changes not required. Life in this sense does not mean human life it means the designed life which would appear based upon much anecdotal evidence to be about 100K. What ever they say the oil does deteriorate and does need changing and in some cases with the exact same oil recommended by the box manufacturer. With that done on a regular basis and the box not abused by driving style then I don't see why 220K would not be achievable. Put that into context in terms of cost on a normal manual diesel by 220K you would probably be looking at having replaced the flywheel and clutch once and be well on the way to number two. Can't really comment on the BMW not having one or ever looked at how they work but most modern auto gearboxes have replaced much of the clever mechanical governers and control devices with electronic computation and electro valves which are often replaceable in situ with a minimum of dismantling required. Your description of the BMW makes me think electronics and I can quite imagine that BMW's price for supply and fit a new ECU could be in that kind of area, which means that with DIY or shopping around it may have been possible to fix considerably cheaper. I too was concerned about the hybrid battery before I purchased my first hybrid a Prius and did a lot of research in what DIY options were available to fix a broken battery should it happen. I discovered that infact it is not so difficult or expensive to replace individual cells. However battery failure appears to be very rare Toyota / Lexus guarantee the battery for a 100K and the way the charge state of the battery is managed is very conservative with respect to maximising life so of all possible problems I think that Hybrid battery failure is one of the last things to worry about. 12Volt system battery is however a different animal an area where the quality of design and charge managment leaves much to be desired, however it is a cheap and easy fix.

The drive train is the strong point of the RX without doubt and the reason I purchased mine, however even here I don't feel that it is anywhere as well sorted as the same system on the Prius in my opinion there are changes that could be made to the software in the area of ICE management that could improve the fuel consumption. Previous to this I had an automatic diesel Citroen C5 and I was seriously considering another, mechanically PSA cars are in my experience pretty good and system integration and suspension is considerably better than anything from Toyota / Lexus. However the amount of anti-pollution stuff built around the average diesel and the problems and cost it can bring are a serious consideration. The Aisin gearbox auto is pretty reliable however like all hydro mechanical boxes it sucks fuel. If going manual the Dual Mass flywheels are problematic. Petrol Hybrid does eliminate a lot of these concerns, hence my choice, however the jury is still out as to whether I stick with that decision :-)

I would generally endorse these comments with the added comment that the seats and headrests are actually quite poor when considering the target market. No auto folding Mirrors, and heat is slow to clear them by comparison with most European cars I have owned. Auto wipe again present, the wipers automatically wipe however the system is not integrated with roof / windows automatically closing them when the rain starts as it is on many European cars. Parking sensors, rear view camera is fine by day useless at night and doesn't really cover the corners. Front parking sensors I have come to the conclusion are if not essential damn useful, the front fender has more overhang than one might think and because the car is big and there is a lot of "give" in the plastic it is easy to touch something and not know it until it is too late :-( I have come to the conclusion that there has been a lot of cost cutting in corrosion prevention / paint finishes. I have never had or seen any European car that looses paint on alloy components like Toyota / Lexus :-( Suspension there are IMHO some serious design flaws here and tyre wear patterns should be checked carefully particularly for inside edge wear. IMHO you will not see much if any in fuel saving over the Volvo so my advice would be to stick with the Volvo as it is probably the better car, I say probably as I have never owned a Volvo so cannot say for sure. Anyway hang on for a few months and the govemint may be prepared to pay you scrappage on the Volvo :-)

Just a thought, I have been looking at fitting third party after market sensors to my RX400H, this in turn has led me to research CAN bus add ons which will enable the sensors below 5 mph AND disable them if the Parking Brake is set so do the genuine Lexus ones work the same way? do you need the parking brake set to kill the front sensors?

I have owned a 2007 RX 400H for about three months now as regards fuel consumption it is a bit of a mixed bag. On a 300+ round trip from Sussex to Bristol I can get 36/37 consistently driving on or slightly in excess of the limits, locally around town short journeys 20-25. When I first had the car I noticed that even stopped in park the ICE appeared to run quite a lot, much more than the Prius. Cutting a long story short I replaced the 12v Battery after which the ICE ran a lot less when stationary. The 12V battery is charged from the inverter so if there is a constant drain on the 12V side the Main Batteries will also be discharging resulting in the ICE cutting in much more frequently. My impression is that the 12V management software in the inverter side is not as clever as I would expect it to be. (And the battery is not the right kind of battery or in the right place for the job it has to do which is in part the reason it seems to give many people problems) The ICE gobbles fuel when cold and I have noticed that starting and running the engine from cold seems to have a disproportionate effect on fuel consumption. Basically if a lot of your miles are going to be start from cold drive two miles to Supermarket / School /Station whatever, let it get cold prior to doing the return trip fuel consumption will not be good!!. My feeling is that the Hybrid Transmission Software is not particularly well optimised for this car and that the ICE kicks in far to early in many circumstances i.e the battery side is not being used anywhere near as much as it could be. (The Prius seems far better in this respect) My techniques for maximising fuel consumption. 1 Set cabin temp to low at engine start (to minimise ICE running just to provide heat) 2 Set the Aircon compressor off unless you really need it. (Not sure just how well this is managed but it has the potential to consume a fair amount of power unnecessarily) 3. Remember gentle braking equates to energy recovered back into the battery heavy braking equates to well polished disks and energy wasted in heat. 4 Try and keep the traction battery as fully charged as possible by using the B position when appropriate. (3 and 4 should be thought of together :-) 5 Keep the power meter as close to 0 as you can or even better deep into the blue sector :-) Having said all that taking into account it's running on cheaper fuel it's no worse that the 2.2 auto diesel estate it replaced and there isn't all the exhaust filter additive stuff to worry about :-) Oh! almost forgot the Prius fuel consumption is reckoned by many to be sensitive to both tyre and tyre /tread design and tyre pressure, certainly when I first owned it with summer tyres a few PSI over normal to improved the fuel consumption, after fitting all weather tyres the fuel consumption dropped a little and variations in pressure seemed to make less difference (but still positive). I have taken the same logic to the RX and run with 5 psi more in each tyre than recommended I mention that because all my mileage figures quoted would have been achieved with these tyre pressures.

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