johnatg

ACEA C3 is very similar to C2 (it's also suitable for diesels with DPFs) but without the fuel economy requirements. Now - does the formulation of the oil (as opposed to viscosity etc) make any noticeable difference to real world fuel economy? Debate......

Yep - I swear by GM Dexos 2 - use it in all my cars and a couple of family ones I look after. Fully synthetic 5W-30 and meets specs of most manufacturers. Here's a typical source: http://www.ebay.co.uk/itm/2-x-5w-30-GENUINE-GM-VAUXHALL-BMW-FULLY-SYN-ENGINE-MOTOR-OIL-5Ltr-DEXOS-2-/281201430441?pt=LH_DefaultDomain_3&hash=item4178e94fa9 But lots more on Ebay. Note that Dexos 2 is a spec as well as a specific product from GM. Be careful to get packs that show the hologram on the top right of the label - and there should be a multi-language leaflet on the back. It is alleged that there is a lot of fake stuff about. Vauxhall dealers sell it but the price from them is apparently about £40 for 5 litres unless you have a trade deal.

I've had these advisories about the covers - said various things were not inspected due to covers fitted in engine bay and underbody. MoT testers are not allowed to dismantle anything. So they can't see the bodywork around the tops of the shock absorber towers for example. But my usual tester doesn't mention them. (On one occasion I had to take it to a local Ford dealer as my usual tester was shut down for the vital month for 'retraining' - ie they'd been caught out by VOSA!)

If you've got the original hybrid blades the cheapest thing to do is get replacement rubbers from a Lexus dealer - about £12. If not, these are said to be identical to OEM blades: http://www.ebay.co.uk/itm/290690410797?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

"Dealers are meant to stand loyal to warranties even if taken to a non main dealers and serviced with reputable parts." Well yes. But warranties whether original or extended, always specify that the car had to have been serviced in accordance with the manufacturer's schedules. The slightest deviation from that is often used as an excuse to refuse warranty claims, even where the claim is for something not related to the deviation. Car related 'agony aunt' columns in newspapers often feature such tales. eg a fuel injection problem where the deviation is a failure to change brake fluid at a specific point.

Quite right. There's nothing complicated about servicing an IS (the spark plug change is a bit of a fiddle as it involves removing the inlet manifold and a load of stuff to enable you to do that). But workshop manuals, workshop data and parts are all readily available and a competent indie should have no problems. Most of the regular services are just inspections anyway - and most of them are done at MoT time. There's not actually much that needs doing apart from oil changes (including diff) apart from MoT inspections. Not sure what extra needs doing on diesels - fuel filter changes I guess - but at least you don't need the spark plug thing! Just save up for the head gasket........ But watch out if you have a Lexus warranty - if you were to claim on that, indie servicing would be a problem. Lexus dealers have you by the short and curlies.....

Or are you flogging round at 120mph + ??

The most expensive tax group prior to March 23rd 2006 was band K - currently £285 per annum, so if a manual 250 was registered before that date it is still now subject to paying £285. On that date (budget day) bands L and M were introduced - L is currently £485 and M - £500. Manual 250s first registered after 23 March 2006 are band L - but autos are band K. Note that there's a budget coming up next week - that's when tax rates might change!

It's due to compromises in the steering geometry. Do a google search on things like Ackerman steering geometry - eg see this: http://www.motor.org.uk/documentlibrary/Sep%2009/TT%20_%20Sept%2009.pdf Lexus pushes the limits of what is achievable with the geometry - they have to build in things like steering feel, weight, tyre wear etc. as well as getting the car round the corner. It's nothing to worry about, unless you want to drive round very tight circles at speed! Just take it easy on full lock.

I'm sure it's not switch bounce - it happens over too long a period. Gradual fade of interior lights is a common feature, especially of 'upmarket' cars. I would guess the fade is done by voltage stepping and cutting internally in the body control ecu and may be one reason why led interior lights are not fitted as standard. It's a curious clash with the map lights and the gear change illumination. Have they worked out how to do fade of leds with more recent cars or do they still use incandescent bulbs?

They are called 'micro-blade' fuses - they are smaller than mini blade fuses. Available very cheaply on Ebay. eg these are micro fuses http://www.ebay.co.uk/itm/MICRO-BLADE-FUSE-SELECTION-TOOL-3-5-7-5-10-15-20-25-30Amp-x120-RR24-Bike-/271741977183?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item3f4515825f and these are mini fuses - longer 'prongs' than micro: http://www.ebay.co.uk/itm/35-Piece-MIXED-Mini-Blade-Fuse-AUTO-Car-Motorbike-5-7-5-10-15-20-25-30-AMP-CA-/221633752746?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item339a66aeaa But I think you will find it very difficult to wire into the fuse box under the dash. The fuse box is actually part of the ecu/junction box and you absolutely cannot get into the back of it to put wires in (And I have one broken into - largely in small pieces and not re-assembleable). I suppose that theoretically you could stick a wire into the front of it if you could identify a suitable power source in an unused fuse position, but having just had to pay for two of these ecu/junction boxes at £600 a piece - I wouldn't recommend it. Your best bet might be to identify a wire that carries sufficient power to feed the camera as well as whatever it is meant to feed and tap into it - but if anything goes wrong Lexus will show no mercy if you have non-standard wiring. It has just cost me over £2000......

Doh! No wonder the fuse didn't blow! Wrong one - I replaced the power window/mirror fold fuse. But I've just tested those - even running both window and mirrors together - no problem. The door locks are protected by a 15a fuse - I'll change that for a lower value tomorrow. Michael - points taken. And no - I can't find the fuse extractor, though I know there's supposed to be one. Been using pliers - actually those fuses need a hell of a pull to get out!

The standard fuse for the door locks is 20a. Can't do any harm fitting lower values - a lower value one may blow prematurely, but that's all. I'd never fit a higher value. The wiring in this car can certainly not sustain big currents. Most of it is very thin/lightweight indeed. But electric motors do cause a big momentary surge/spike on start up - that might be why they fit fuses way bigger than obviously needed. Re PO-40 - no. My original one is on it's way to Michael and his techs, and he's sending me a replacement which hasn't arrived yet. I must say he has been most helpful - several private emails apart from public corespondence here.

I suspect that they dumped the parts last Thursday when they fitted the new ones. I collected the car on Friday 'cos they said they wanted to test it some more. Hmmm.... I intend to write to the dealer principal about the 'warranty' on the part fitted the first time. It really isn't good enough, is it? I fitted a 10a fuse in place of the 20a one protecting the door lock (in the fuse box under the dash driver's side - actually part of the junction box/ecu). Ran it through quite a few lock/unlock cycles - it didn't blow - no problems so far! I just knew that fuse was too damn big. Maybe I should try 7.5a! I'll give it a little while though. I'd be interested to know if there are any Tech Service Bulletins about this, but I doubt it - Lexus Stockport claimed they had been on the dealer forums (where they no doubt complain about irritating customers just like we complain about them ! ) and they said no-one had come up with anything. And the guy who did the work said he had never replaced on of these JB/ecu units before.

I think they're the same - need to check the part numbers. Does someone here have a parts list? The 'engine bay' ones are the main sensors, used to adjust fuel/air ratios. The ones further down the exhaust are post-cat - they are used to check that the cat is doing its job by comparing O2 exhaust content with the pre-cat readings (some predictable amount of O2 is used in the cat process) Correction 7/2/15 - they are NOT the same. The upstream ones are heated, the downstream ones are not. The connection plugs are different.

No - I wasn't offered the old parts this time and I forget to ask in my shock at the new bill! Does make me wonder a bit though - it had occurred to me since - did they realise themselves that sort of thing might have been the problem all along and they didn't want me to know that's what they'd found?

That's listed as fitting extensively across Toyota vehicles and including IS200 and IS250. So it will most likely fit and work OK. One caveat - the guy who does electronic advice in 'Car Mechanics' mag always says to fit a genuine oem oxygen sensor - maintains they give better results than generic ones. But this one could well be oem anyway - after all, Denso supply IS250 spark plugs, so why not oxygen sensors? And this looks like a good saving.

At the moment I have no problems. I'm just trying to establish what might have caused the problem before to try and forestall it happening again. Maybe there was in fact a problem with the loom. I feel as if I'm in a bit of a race to identify the basic cause versus running the car as it is - is it now A-OK or not?!

Mark's post has prompted me to do some more dismantling of the original Junction box/ecu (!) and indeed under the circuit board I showed originally there are some bigger components, including two ics with approx 130 pins each along with some big capacitors. There isn't really any damage evident on that side of the board except to the connection links to plug P1 (see page 14 of the Door Lock control circuit pdf which Michael provided on page 3 of this topic). The wire links are badly burned, especially pin 1 but also pins 5 -10 and 12 and maybe one or two more on the bottom row - does that provide any clues? I thought the door lock was mainly controlled from pins 1-4. I've also realised that the fuse box under the dash, driver's side is actually part of this Junction Box/ecu - at least that's a handy source of some more fuses! The rh door lock fuse is 20a - does it really need to be that big? Even at 5v that means it can pump in 100W. Any idea how much peak power the door lock really needs? Thanks!

Diesels aren't good for short journeys. But if you can give it a good thrash at least once a week you should be OK..Change to a 250 whenever you can afford! The £285/£485 tax thing is due to auto vs manual. Manuals are £485 per annum, autos £285. You might find that surprising and it is - it's because the auto emissions are 214 g/km and the manual 231 g/km. Dunno why manuals should have so much higher emissions than autos - usually it's the other way round. If you were to get a manual (don't!) registered before 23rd March 2006 it would have £285 tax - that's when the higher rates were brought in.

It's not the body control ecu, which is located on the nearside (left) of the dash. It's the junction box, which is located on the right hand side just behind the dash panel. It's certainly the most complex junction box I've ever seen, but it's circuit board consists almost entirely of resistors and capacitors with a few diodes etc - there are (apparently) no logic elements there. See a photo, links to which were posted back in this topic somewhere. I haven't got (or seen) the second one, but am told it (the burn) was very similar. I agree entirely with Mark's diagnosis, had reached exactly the same conclusions and tried to emphasise the things he said there when I took the car in to Lexus last week. As I said, I don't think they were too impressed - garages never are when you try and tell them what's wrong! I guess Lexus tech also came to that conclusion, which is why they told L Stockport to change the loom. But I'm not at all convinced that they checked the lock properly, except in so far as to say 'well, it works now'. Which it does....

Thing is, apart from this one electrical problem, which hopefully is now cured, it's perfect - and only done 46K miles. Absolutely no reason it shouldn't be good for another 100K! And it's had no problems otherwise since I bought it 3 years ago. Not me to give up on a car! But I must admit - IS250 electrical systems are more than I can cope with - but also more than Lexus dealers can cope with too, I suspect! I usually keep my cars for a long time and a lot of miles - my records are 17 years with a Pug 205 (that was my wife's, but I kept it going), 15 years with a Fiat 128 (originally mine, but passed on to my wife), 115K miles with a 1960 Sunbeam Rapier, 90K miles with a '88 Mazda 626, 90K miles with a MX-5 (not my present one - that's 23 years old but I've had it for 9 years) - those are in my ownership, not totals - and several others for a long time and lots of distance! You get the picture!

The mirrors fold/unfold smoothly, quietly and at normal speed with the internal button. And with the PO-40 for the brief period between burn-outs of the junction box. I am considering replacing the fuses protecting the door locking, window winding and mirror folding with smaller value ones - all are at present 10 or 20 amps. I have a good supply of 5, 10, 15 amp fuses.and could easily get more. What do you think, and which ones would be useful to replace? Even if they blow, at least we might find the minimums which will work in service and provide some protection?

Well, I've got it back - so far so good........ Another gut-wrenching £1138 though... :(

Yes it was. And I checked that the lock/unlock and mirror fold worked before I drove the car away. Whilst it was parked up I did unlock it once and then single locked it, and it was the next time I unlocked it that it failed after a few seconds.