johnatg

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!

OK - this isn't too bad: Not exactly the same as the Lexus. Blade removal from the arm is pretty much exactly the same as Lexus. Rubber replacement is a bit different - Lexus rubbers involve two little teeth at one end on the metal strips as I recall, but otherwise pretty much the same. Do one blade at a time so you can check assembly on the complete one if you get confused!

Here's how to get the blade off the arm. It's not absolutely exactly the same as the IS but close. It shows replacement before removal, but keep watching! Still looking for a useful vid on the actual rubber replacement!

Theories - theories. What I've come up with is that maybe the door lock motor in the driver's door (incidentally - the Workshop manual describes them as 'motors' rather than 'solenoids', and indeed they run in opposite directions for locking/unlocking and I think motors are usual) has too low a resistance. The WM specifies that the resistance between terminal ACTD (see the first diagram of Michael's a few posts back) is greater than 10 K ohms. If it's less the motor will draw too much current. And the socket known as PL1, which is on the Junction box and is where the door lock circuit plugs in, and where ACTD is terminal 4, is at the epicentre of the burn on the JB circuit board. (BTW - it is where the PO-40 was connected to - Light Green in the car at Connector C to White of the PO-40. The instructions do say that European cars 'may work better with White connected to Thick Red of C'. But mine did work OK - apparently. Did.) Anyway, I discussed all that with the technician who worked on my car this am - I don't think he was too impressed with me advancing my theories, but he is mortified that a job he has worked on has come back so soon. He did say that the JB works on 5v - that may be true, but surely the power provided to the motors will be 12v so there must at least a 12v power bus in there along with the 5v electronics? I've yet to hear any news....

To get the blade off the arm you swing open a sort of clamp which is just beyond where the arm meets the blade. Then you can turn the blade through nearly 90 deg and slide it off the hook at the end of the arm. It's the standard way that flat and hybrid blades fit on to hooked arms.

Good question! Most of the fuses 'protecting' these circuits (in fact protecting most of the Lexus electronics) are pretty high value - eg 10 - 20 amp. You can get a hell of a lot of power (140W +) through that without the fuse blowing - but plenty enough to overwhelm delicate components - I guess - don't you think? I suspect all the power needed to drive eg the door lock motors goes through the junction box.

Thanks for the diagrams Michael. I can't see that they show the switch panel in the drivers door - I would like to know how that connects in to the junction box or whether the switches operate the locks and windows directly. It puzzles me that the locking switch locks and unlocks all the door esxcept that it won't unlock the drivers door. I'm beginning to wonder if the door unlock motor in the drivers door is the problem. I think the 'RH door' indication is a syptom rather than a cause. It now shows 'Trunk open' too. A short in the wire to the sensor would just show 'RH door' all the time (ie just as if the switch was made) - that would prevent the doors locking but not affect the windows and it wouldn't burn out the junction box. PO-40 connections (following instruction 5.2, 9 wire) - Red PO-40 to Blue of connector B (big type) . I connected it about three inches from the connector inside the trunking. White PO-40 to Light Green of connector C - connected just before the plug near the back of the drivers door. Blue PO-40 to thick White of connector C , again just before the plug near the back of the drivers door. All T-connections made by cutting the host wire then inserting two wires in one end and one the other of a crimp connector. As for 'where are all the others' I have been contacted by someone else with exactly the same problem but he doesn't want to say too much about it at present. It's a 2009 pre-facelift, but a different part number for the junction box. Having said that I don't believe frozen mirrors were the problem - everyone (in N Europe at least) would have had the issue by now.