johnatg

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.

Just one correction there - it was a couple of days before the second Junction Box burned out, but I hadn't gone anywhere - just drove home from Lexus - about 10 miles, and parked up. Next time I opened the car, after a couple of minutes idling whilst I cleared ice from the windows, the 'RH Door' sign was on all the time again - it had gone again.

I just hope I can love the car again!

Well, they've fitted a new door loom and a new junction box and they claim that everything works OK. But they haven't found anything else. They are keeping the car at least until tomorrow (Friday 30th) to do some more tests. I'm nervous about taking it away - it's going to get a good dose of door locking, window winding and miror folding before I do take it.

I'll let you know how that all goes!

Have you got LED bulbs? The two outer bulbs are brightened gradually, I think by feeding them with a gradually increasing voltage. This seems to cause LED bulbs to flicker.

But if they flicker continually it might be because the bulb contacts are a bit weak and need tightening up, or the contacts are dirty.

Look for a guide here or elsewhere on line to check how to access them - and use plastic trim removal levers if you don't want to mark the housings.

My theory, anyway!

In the first instance, check the Battery terminals - loose ones can give this sort of thing.

But the problem might be deeper than that!

OK - diesels have bigger batteries - not sure of the code for the size. But for a IS250 you're looking at the top one and it's wrong - if you put it with the terminals to the bulkhead side it will be reversed. And if you put it as per the schematic, the terminals will be on the 'front' side rather than the 'back' - bulkhead - side.

The sketch is a 069 yes? A 068 will show the terminals like the bottom schematic but same dimensions as the top one.

Actually, you probably don't need a Battery - that's pretty horrible corrosion on the earth terminal and could well be the source of your problems! Clean it up and put some protection on the post and terminal - Holts 'No-Crode' if you can still get it, or Vaseline. And check where that earth cable attaches to the body - could well be as bad.

Second that - Mark is absolutely correct - you need a 068.

Note that these are fairly rare - not all Battery manufacturers make them and they will not often be in stock at your typical Battery supplier. You'll be fobbed off with something which will 'do'. You can get a 069 in (much more common), but it won't fit properly and will put the terminals in the wrong position. Or you'll get one with the terminals in the correct position but it will be smaller than the proper Battery.

EuroCarParts/Carparts4Less (and others) stock the 068 (usually) - eg Bosch S4026 (my favourite), etc.

Thanks for the inputs, guys.

Just to establish my own credentials, in the past 45 years I have only twice taken my own car to a garage etc - that was for a couple of clutches when I didn't have the time. So I have a lot of experience of fixing stuff - I once succesfully repaired the wiring in the dashboard of a Mazda 626 after an electrical fire (caused by some previous owner mumpty having bypassed the fuse protecting the rear fog light - I traced that problem to chafed wiring in the boot). And I can tell you - I can well understand why wiring fires can write a car off - it took me ages to replace every wire. But that was extremely simples compared with the Lexus.

I spent quite a lot of time trying to find what is wrong with the Lexus - it was a hard decision to seek help. I have no experience at all of finding a good auto electrician and anyway there's actually not much they can do that I can't. The Lexus wiring is extraordinarily complicated and I figured (maybe naiively) that a dealer was the best place to turn to. We shall see - eventually.

Meanwhile the PO-40 will shortly be on its way back to Michael - he's going to get it checked by his techs. But it's been working fine for months (and was working again after the first junction box replacement) and I have no reason to suspect it or its connections.

Watch this space!

Another update - getting a bit p***d off now - door loom is on back order and should be delivered on the 29th. Meanwhile - nothing happening and they still haven't got a clue as to what is actually wrong (they don't really suspect the loom - it's just that Lexus tech won't help until the car is back to standard). I can see this ending up costing more than the car is worth.

I haven't been supplied with a replacement car but I don't really need one.

Well, sometimes warranty work is to fix manufacturing faults but it's also done to fix faults which arise in service during the warranty period, formal or otherwise sometimes. If the head gasket hasn't been replaced it probably hasn't got a manufacturing fault in the head gasket area and the problem hasn't arisen.

I'm afraid it's wishful thinking that if it's been done it for sure won't go again. Or even if it hasn't. IS220Ds seem to have an Achille's heel in that the head gasket blows. Probably not due to a manufacturing problem but more due to some inherent design problem. Lexus have, after all, given up on diesel engines!

But they don't all go at stupidly low mileages. Yours could last until you want to sell the car anyway. Roll the dice!

Re the warrranty - as long as it's been serviced properly the warranty should still apply. The problem is - proving it's been done properly. Just one minor thing (even if apparently unrelated) can blow the whole thing.

I'm not sure why you would be so keen that the head gasket has been replaced. That's not a good thing. It is generally done because the car has overheated, or the blowing itself causes the car to overheat and that tends to warp the head (in any car, but the IS220D seems prone to major damage). And in that case the head needs to be replaced, if not the whole engine. All that sort of thing is very unlikely at 25000 miles.

But it seems to be common (but not inevitable) before 100K miles!

There's certainly no head gasket work there. The exhaust gasket replaced does fit to the cylinder head, but it is not the gasket which fits between the cylinder head and the block, which is the major expense one if it blows. The EGR gasket is between the exhaust manifold and the valve.

EGR work is common on diesels (they get blocked, expecially if the car is used for short journeys).

To repeat a theme often seen on here - modern diesels (ie ones with EGRs and DPFs etc) are only suitable if you do big mileages on motorways. Otherwise they are nothing but trouble.

Quick update: The Junction Box fitted last week was burned in much the same way as the original (but I haven't seen it). Basically now they haven't got a clue. They've consulted Lexus tech - the first thing that they want is the door wiring loom replacing so that it is 'as new'. That's gonna be about £250 for the parts (+ labour).

Watch this space......... :(

Is this the 'floor mat-interfering-with-the-accelerator pedal issue'?

But the accelerator is fly-by-wire so there's the possibility of an electrical/electronic fault?

It looks modern and nice! And it's fashionable! And it does make the car marginally quieter. But really the centre cover is dead easy - just pull. I agree that the others are a bit of a pain. The front one is possibly important for aerodynamics (of engine intake and cooling air)

In cold countries like Norway they fold the wiper arms up off the screen when they park at night. Probably a good idea, but I can never remember to do it!

I did once totally destroy the wiper mechanism (on a Vauxhall Cavalier, I think) because they'd been left switched on and were frozen to the screen. Very inconvenient start to the day - no way you're going to be able to drive anywhere on a cold frosty morning with salted roads with no wipers!