ChumpusRex

There is a body control ECU on each side of the dash. The photo you posted is the main (right side) body ECU. Lexus call it variously either "body ECU right side" or "cowl side Junction box Right", mainly because it is basically 2 parts fused together. The ECU needs more connections than it can fit, so it is built into a junction box. The ECU is the white middle layer in the photos. The junction box is the bottom layer, and the gateway ECU is the small one stuck onto the top. The main burn appears to be on the bit of the ECU PCB where the drivers door open switch connects in, which probably explains why this was one of the first symptoms, but there is nothing high power that connects there. I suspect the big diodes (and some big components on the other side of the board) do some heavy duty switching, and that is what overheated.

Would be very interested to see more detail of the failed junction box assemblies. In my experience, most of the modern ECUs like this are heavily protected internally. I've only ever seen two or 3 catastrophic failures like this, and they have always been short circuits in the loom. I can't match the photo of the failed PCB up with the outside of the ECU, so I assume it is some sort of internal intermediate control, though given the fault description, it does sound like the problem was the locking circuit. The switch issue could be a reflection of the fact that the body ECU sends the door switch signal to the dash, and that the ECU was malfunctioning at that time. The locking motors are reversible - the ECU connects them one way round to lock, and the other way to unlock, and disconnects when idle. A short to ground or 12V on one of the lock control wires could certainly cause this type of burn out. Ashpoint has posted an extract of the wiring diagram with these wires highlighted. I'd check these wires very carefully, as they are my prime suspect. Being unable to lock the door, suggests that the lock motor might have been jammed on in unlock mode. The other thing is that the body ECU doesn't do very much high power stuff, except for the door locks and the windscreen wipers. Most of what it does is sensors, controls and interior lighting. I don't know what a P0-40 is, but I guess it is something to do with the mirrors. The mirror retract circuits are nothing to do with the body control ECU. So I doubt it's that.

Mine was broken. I fixed it with some epoxy putty and aluminium repair mesh. This wasn't strong enough. So I had to drill it, and put bolts through the epoxy to hold it on.

Was the car actually misfiring? It would have been shaking and shuddering, if it was - sometimes you might notice this after about 10 seconds from a cold start, there will be a bit of juddering and the revs fluctuate. I've checked this on mine with a diagnostic tool, and it shows that there are a few misfires, but that the ECU is ignoring them due to engine conditions. However, a major misfire strong enough to put the flashing light on will be making the car judder quite obviously. With mine, it wasn't actually misfiring - it just had the light on. I shut the engine off and restarted, and it was fine. When I put a diagnostic tool on, there were no codes. This makes me think it is some kind of software bug in the ECU, which can be triggered when you get a bit of misfiring during warm-up on a cold morning when the ECU is running the normal cold-start program, but where it's not cold enough for the ECU to run the sub-zero cold-start program.

Flashing engine management light means "serious misfire with risk of engine or catalytic converter damage", and to stop the engine as soon as safe. A solid engine light means "engine or transmission malfunction". That said, there does seem to be a problem with the ECU software, because I've had exactly the same flashing light, check VSC with no misfiring and no codes stored. The problem happened after a cold start on a coldish, but not very cold day, when during warm-up the revs had some fluctuations. Normally, the ECU ignores misfires for the first 30 seconds after start-up. But it seems that the fault detection can go a bit haywire, and that a temporary misfire that occurs at the instant when the ECU switches from cold-start mode to warm-up mode, can confuse the ECU and cause it to indicate a critical misfire.

Haha. In all honesty, I hadn't thought of flipping it back to front, and was thinking that you'd have to have the terminals the other way round. The battery bay isn't quite symmetrical, so you might have to cut a notch out of the battery cover.

Those are the wrong batteries and will not fit (the terminals are in the wrong position). The IS250 requires a size 068 battery such as Bosch S4026 or Varta E23

The 0W or 5W refer to viscosity at - 20C. So the 0W is thinner at - 20, but will not thin as much with temperature. At normal UK Winter temperatures, the 5W-30 is probably thinner when cold, or the difference is so tiny it can be neglected. 0W-30 is a more expensive than 5W-30, so I wouldn't specifically advise it.

Ah. I've got the hooks for the mats, but the problem is that they don't stay locked into the holes in the car's carpet- they pop out. In this case, I hadn't noticed because I hadn't cleaned the car recently due to weather. This is basically exactly what happened to me: http://blogs.cars.com/kickingtires/2009/09/explaining-the-toyota-floormat-recall.html Looking on ebay, it appears that there is a new design of hook which actually locks into the carpet - although it doesn't appear to be available in the UK.

Beat me to it. I discovered that it was the mat. It had slipped forwards slightly. So, if you pressed the accelerator hard, the edge of the pedal would slip under the mat, and the mat would stop the pedal from coming up.

I was driving back home today, and took a junction quite quickly to nip in front of some traffic. Once I got round the junction, the car continued to surge forward even after I let go of the accelerator. Revs banging along at about 3500. After slamming on the brakes, and having the engine labour against the stopped car at about 2500, I dropped it into neutral, the revs jumped and then dropped back down to idle. I was able to get the last bit of the way home without incident. Has this happened to anyone else?

Yes. It's high revs to warm up the engine. All modern cars do it, but most Japanese cars tend to rev a bit higher than European ones when cold.

The genuine Toyota pink is expensive. You can get it for around £35 for 5 litres online. There is no generic similar antifreeze on the UK market. However, all the Japanese OEMs have used the same formula from the same OEM since 2007. So any Japanese coolant designed for late model cars is exactly the same. You can sometimes find other makes for less - some people seem to be able to get the mazda FL22 for £13 for 5 litres online. It's the same formula but green.

There is a dedicated DVD digital sound cable from the back of the DVD player to the amplifier in the boot. It connects to the small blue socket next to the fan in eric's photos.

Press the power button once without foot on the brake to turn the radio only on. Press the power button twice without foot on the brake to turn all electrics on and get engine ready, but not start. With engine running: To turn engine off but leave radio on, put gear selector in neutral and press power button once. To turn car off completely, put gear selector in park and press power button once.

Thanks for the correction. My fault for oversimplifying it a bit in order to keep the post short.

The only answer is to ask your insurance companies any if you need to declare a modification. I'm general, anything that is not a standard factory fit feature for that trim level may be regarded as a modification; including factory fit options. Bulbs, brake pads, etc. are not generally regarded as modifications if they are E marked, indicating that they are an exact replacement for the original part with identical performance.

In order to be E marked as Road legal, the bulb must be exactly the same brightness as the original. The osram cool blue bulbs are. I've never seen a 6000K or higher bulb which is as bright of original. I don't think the technology to do this actually exists, but am happy to be proved wrong. Even the Philips aftermarket 6000K are simply too dim to meet the standard and are only available in Japan where the law is different.

Osram night breaker are halogen - much dimmer than HID. Only suitable if your car takes halogen bulbs. If you have HID lights you need a HID bulb. Night breakers are OK, but they are only designed to run for 100 hours or so, so you'll be changing them every 3 - 6months. I have OEM HID on my car, and when the bulbs burned out I changed them for 6000K D4S bulbs - they worked, but when one of those burned out I put Philips D4S in and it was much brighter. Visibility was so much better. I've seen 10000K on display and they are a lot dimmer. Even the eBay sellers advertise them as 30% less bright,which is saying something.

Technically, if the bulb isn't "E" marked, it is illegal. Only 4300K bulbs can be E marked. Cheap HIDs, even of the same colour, often aren't E marked. In reality it makes no real difference, as no one is going to take a bulb out to check it - except in the situation in which some terrible accident happens, and you get prosecuted for CDCD or CDDD, and the cops are looking to nail you to the wall.

My experience is that anything other than a genuine "big brand" HID lamp is a waste of time. I put some 6000K HIDs in mine. Although I kind of suspected they were a lot dimmer, I didn't believe it at the time (as I replaced both bulbs in mid-Summer when I hardly used them, and shortly after I got the car, so I wasn't familiar with what the headlights were meant to look like. The first 6000K burned out after about 10k miles, at which point I changed both bulbs for Philips. When I eventually replaced it, the difference between them and Philips 4300K was night-and-day. The 6000K was so dim, it was barely better than a regular halogen. I've seen some other HIDs on display, and the 10000K are a lot dimmer still - plus the blue light they give causes a lot of glare, especially in fog. Not recommended - the light quality simply isn't good enough. Fair enough if you want to try, but it's a lot of work changing the bulbs because they are very difficult to get to. Just be aware, that the "show" colour HIDs are generally of poor quality, dim and burn out very quickly.

Is it because of the fuel injection setup or for some other reason? It is because of the fuel injection and ECU setup, and the IS being a rare car, that no one has bothered making a kit for it. There are plenty of DI cars out there which have LPG conversion kits available. Direct injected conversions are mechanically easier than normal conversions, because you don't need any mechanical engine mods - like gas injectors, vaporisers, etc. Direct injection systems work at super high pressure normally, and at these pressures, the LPG will be a liquid, so flow, pump and inject just like petrol. You just connect the LPG pipe to the engine's fuel pump via a selector valve (for petrol or LPG) and the LPG goes through the normal pump and injectors. However, like all fuel injected LPG conversions, you need an ECU remap because of differences in combustion between LPG and petrol. The difference with DI, is that the ECU has a lot more control, and therefore you need a much more complicated remap. Designing an ECU map is a ton of skilled work, especially on modern DI ECUs which can have up to 250,000 different individual parameters to tweak. I'm guessing that there has been no demand for the tuning companies to develop an LPG map for the IS250. In fact, I've not seen anyone offer a remap for the IS250 for anything - probably because of the complexity of the system, and the fact that Lexus have strong security systems on their ECUs to prevent unauthorised re-mapping.

Yes

Prestone is an conventional "universal" organic acid formula. It'll work. However, Japanese car manufacturers designed their own specific formula which is a special "hybrid" organic acid formula, which provides better water pump seal protection than a conventional pure organic formula. The prestone is "phosphate free" whereas toyota/Lexus require a "phosphate based" coolant. In most of the UK and Europe, the ONLY "phosphate based coolant" you can buy is the OEM fluid. How much difference this actually makes is anyone's guess. Obviously, prestone seem to think that it doesn't make any difference. I'm sure that if you replace the coolant with prestone you won't run into too much trouble provided that you dilute with distilled water. Once phosphates go into a cooling system, you can never flush them out - they stick to the metal. If you mix hard water and phosphates, then you risk them reacting and forming scale and grit.

Fuel additives for the IS250 aren't that useful. The IS250 uses common rail direct injection. This uses enormous fuel pressure which results in a super fine fuel spray. Because the fuel pressure is so high, it is virtually impossible for an injector to block; even partially. I've used the Archoil 6400, which in all honesty, didn't really do much to the car's performance. It did, however, leave a thick deposit of iron on the spark plugs. My worry with using this type of fuel cleaner, is that it may contain metallic additives that build up on the spark plugs and cause them to fail. As the IS uses very expensive ultra long life spark plugs, regular use of metallic additives could theoretically shorten the life of the plugs. The big problem with the IS250 is carbon build up on the intake valves - this is more to do with the engine oil (which gets sucked in through the crankcase breather system) and inadequate sealing of the piston rings (a design flaw). That said, the problem is MUCH less severe in the UK than in the US, because the valve timings are different due to different emissions standards. The valve timings in the US are much more likely to cause build up on the valves. There really isn't a way to fix the build up, except for using an oil designed to minimize it (A good quality synthetic oil meeting the API SN standard should be reasonably resistant to valve deposit build up). I've used BG MOA to "fix" a rattly cam adjuster (another design flaw). I don't know what else, if anything, the MOA did, and I don't know why it fixed the cam adjuster. It is possible it was because the wrong oil went in at a service (independent Bosch service centre).