Delphius1

Hi, If the spare is a few mm different diameter than the other tyres, then yes, it could confuse the traction control system and cause it to engage. The problem is the system sees a wheel rolling at a different speed and assumes it's slipping, so the traction control reduces power to stop the slip. At higher speeds the difference between rotation speeds is a smaller fraction, so the traction control doesn't get involved. A friend had a BMW with a faulty ABS sensor that caused a similar problem, misfire at slow speeds which went away above 40mph. I stuck an OBD scanner in the port, found the duff ABS sensor and once it was replaced he was good to go. I had a job convincing him the car was working normally, based on the duff information the sensor was giving it. He was convinced the car had a misfire and was going to replace all the plugs and ignition coils. These safety systems are great when the car is perfect, but they can quite easily be thrown out by faulty sensors or even something as simple as a mismatched tyre. You really should replace all 4 tyres on the car at the same time and rotate them around the car at intervals, because uneven tyre wear can cause issues not only with TC ABS and VSC systems, but also the AWD system. Luckily on the 400h there's no direct connection tween the front and the rear axles like the RX300. OBD scanners are essential kit on modern cars. Most garages should have a professional scanner that will give you any fault codes. But they will charge to do it.

Do you have any abs or vsc warning lights on the dash? Loss of power at slow speed especially when cornering tends to suggest a possibly traction control or stability control issue. The safety modules see an issue and cut the ignition, which can feel like a misfire, which to all intents and purposes that's what it is. It's just the modules cutting the spark. Unfortunately on a complex car like the RX, the only real way of knowing what is going on is to hook it up to a diagnostic unit, preferably a PC running Techstream. That way you can see what if any error codes are in the various modules. The tyres may be an issue: what tyres did you fit and did you fit 4 identical tyres?

Hi, The answer is probably not, because the faults will come straight back and illuminate the warning lights again. You'd need to find out what is causing the warning lights to come on and fix the fault before the lights will stay out permanently. I'm pretty sure ABS/VSC errors are one of the type of errors that come back immediately, unlike powerplant errors that take a couple of heat cycles of the engine to come back. So clearing the code is no use because it will come straight back as soon as whatever is causing the issue Is sensed by the ABS system. It may be the suspension that is causing the lights to come on. You'd need to hook the car up to a diagnostic terminal to see what error codes are being flagged so you can see what is causing the error.

Keyless entry is not something I like due to the ease of theft from cloning attacks. Keyless is a step down security-wise. I hope you have the keyless fob for your IS in one of those RFID pouches to prevent cloning. I've never had my Genuine Lexus key break on me, they seem to be pretty robust. My other key is one of the cheap Chinese flip-blade cases and all I do is order a couple at a time for a fiver and swap the blade over when the case breaks! So far they're lasting about 18 months per case.

It doesn't surprise me that there's an increase in noise and vibration after fitting a catloc. Something that is designed to attach a cat as firmly as possible to the car to avoid theft is bound to add some noise and vibration into the cabin. If it wasn't as firmly attached, then it would be easy to steal the cat. Manufacturers go to great lengths to isolate the exhaust from the body using rubber mounts. Of course you can't rubber mount a catloc because thieves will just cut through the rubber mount and still steal the cat. I'm not sure what the solution is unfortunately. Possibly a substantial steel sheet/under tray bolted under the car that covers the cat to deter thieves so they move on to an easier target? Not sure if there are mounting points under the car on the subframe etc. to do that, but at least with security head bolts it would be hard to remove and provide some security. If you design it right you can say it's a bash plate for your hard-core offroader? Although being an RX that might be a hard sell. :-D

The tow package oil cooler in the US is associated with the transmission fluid, not engine oil. The engine oil cooler is associated with the oil filter. I believe it's a liquid-cooled cooler. Oil passes from the oil filter housing to the cooler and back again originally via rubber hoses (that break down due to heat and eventually leak). The final update was to change the assembly for semi flexible metal pipes between the two units. There are a couple of videos on YouTube. This one is about the clearest: As the fault and the fix/update is pretty well known, you'd think a dealer would at the very least advise a customer there is a potential weak spot that should be addressed. Then the customer can decide if they want to take the risk or have the issue fixed. Especially if the car is being dealer serviced, the dealer should be aware and advise the customer accordingly. Unfortunately I don't think it's a recall, so it's not mandatory. But it's just good customer service to make a customer aware of such things and avoid the messiness that ensues when there is a preventable failure. The key word is preventable.

The oddly worn tyres could be a factor. Not having 4 even tyres can have wheels rotating at slightly different speeds and wind up parts of the drivetrain enough to push gears into each other and cause mild vibration or gear noise like a sight whine. Not an easy thing to check though unless you're prepared to go to the expense of fitting 4 identical tyres. .

P0125 code is insufficient engine temperature detected to switch to closed loop mode. The ecu has exceeded the wait period for the engine to get warm enough to go closed loop. So you're effectively running in cold engine mode. Like running with the choke on all the time. Fix that issue first so the engine management goes into closed loop mode and uses the oxygen sensors to check the mixture. You can't look at the lean running issue until the engine management goes into closed loop mode. Insufficient engine temp could be a bad or disconnected coolant temperature sensor. Or there could be no coolant getting to the sensor to warm it up. A simple OBD2 reader will give a live reading of engine temp. A broken sensor may read low, or get to a certain temp and stop increasing. You'd have to check to see which it is.

I deleted the metal pipes bolted under the radiator and just ran hoses between the transmission and the cooler, which is what looks like your previous owner has done. I can say from experience it's not easy to tighten up the hose clamps because there's very limited space to get hands and tools in. It may be just the hose clamp needs tightening and everything should be fine. Personally, I'd try loosening the clamp off, try and get the hose pushed on a bit further and then re-apply the clamp and tighten it up so the leak stops. Fingers crossed that should work, unless there's a pin-hole leak on the metal fitting on the cooler. Edited to add: I used rubber hose made for oil coolers, I didn't use Silicone hose, so can't really comment on the suitability of Silicone hose for oil cooler applications.

I've done the key programming thing from scratch, so I have a bit of experience. ;-) I posted back in 2018 my experience of getting key electronics programmed to my RX300. I'm not sure if the 350 is the same. It's worth a shot anyway. I assume the key starts the car fine, it's just the central locking part of the key that has become unsynchronised with the central locking module? If the key fails to start the car, then something else is wrong. To get the central locking module to re-learn the key's code, here's the procedure I posted back in 2018: The programming goes something like this. (I did it at the speed you can read this text) Sit in car with drivers door closed Open drivers door. Key in ignition, key out of ignition, key in ignition, key out of ignition (Don't turn the key, just insert it into the barrel and remove) Close drivers door, open drivers door, close drivers door, open drivers door, Key in ignition, key out of ignition, (don't turn the key as above) Close drivers door, open drivers door, close drivers door, open drivers door, Key in ignition, close drivers door, turn ignition to on (lights on dash), turn ignition off and remove key Central locking locks doors... wait for doors to unlock, (you have to wait for the doors to unlock before the next step. It may take a couple of seconds) Press lock & unlock buttons on key fob at the same time for a second, release, then press lock button within 3 seconds Central locking should lock/unlock. Key is now programmed: open drivers door to cancel programming mode.

Yes, I'm pretty happy. Some people might think it's overkill to use Techstream and spend a couple of days reading the manuals to find the fault is just a teeny switch, but these cars are so complicated you need it all to see where the fault really lies. Without it, you don't know if it's the dimmer switch, the dimmer resistor, the light sensor, the wiring, or the modules themselves. All the above are involved in the simple decision to dim the instruments and the nav display. Plus those signals go through about three different modules. Without finding the fault first you could be dismantling half the car, swapping modules, sensors and switches out and still not find it. Plus I've learned a fair bit about the car whilst looking through the info.

Herbie, I don't like throwing money at problems, I don't have a lot of it to throw about! But this was a good little exercise. The thing that threw me initially was the fact that you had the dimmer signal and the T/Cancel signal was entirely separate. But then looking on lots of pages of the info you sent me, you could see the t/Cancel signal was promoted to the other units. The eureka moment was then understanding that the t/cancel signal overrode all the other inputs to modules (light sensor, headlights on/off, etc). So the problem did boil down to that pesky little switch in the dimmer/Odo panel. Luckily Techstream can tell you the state of the tail/Cancel switch without pulling the dash apart. That's really handy! I could see the fault before I started pulling things apart. Thanks very much for the info you sent, I couldn't have done this without it. With your info and Techstream, it boiled down to a 15 minute diagnostic check to prove the problem. It just took couple of nights looking through the circuit info and the module signals to pin down what I should be looking for! Shows you how complicated these cars are. And then getting time away from Christmas shopping to hook everything up and fix the problem. :-)

The Dimmer is now Fixed! As I hate it when people post up faults and never post a resolution and how they fixed the fault, here's how I fixed it. Thanks to Herbie's information, I could see that the Tail Cancel signal (the signal that allows or denies the dimmer to work) is set by the dimmer switch (independent of the dimmer resistor value). The dimmer switch connects into the instrument panel, which is a control module all of it's own. The Tail cancel signal is promoted to all other modules from there. I fired up Techstream and went into the instrument module live data. I could see that the variable dimmer resistor changed from 0-255 as before. But, the tail cancel signal didn't change as the dimmer switch clicked. So there was something amiss with the switch in the variable resistor. So, I pulled the dimmer/Odo panel out of the dash for more investigation. Luckily the dimmer unit comes apart easily with two screws at the back. Looking at the front part, you can see the white circular thing that is turned by the dimmer knob. Not the missing quadrant (the chunk out of the side). Ignore the metal strip, that's just the stop so you can't keep turning the knob. Now I looked at the circuit board that screws to the back of the unit. You can see the variable resistor that the shaft of the dimmer knob locates into, but at the side of it is a microswitch (the thing in the middle of the board that sits up from the board). That microswitch runs along the outer edge of the white circular disc. It's switched on and off by the missing quadrant. Looking at my switch, initially it was missing the brown lever on top of the switch. Noticing there were holes for a hinged lever, but no lever, I turned the front part upside down and shook it. Lo and behold, the brown lever dropped out! So I refitted the lever to the microswitch (it's a bit fiddly as it's absolutely tiny!), as you can see in this picture: I plugged the bare circuit board back into the wiring, switched the car's ignition on. Then covered the light sensor on the dash. the lights came on but no dimmer. So I pressed the switch. Success! the dash lights and Nav display dimmed! A cheap fix, with no parts needed! I screwed the dimmer/Odo unit back together, refitted it and turning the dimmer switch clicks the microswitch and dims the dash. Now I can enjoy a less dazzling drive in the dark. No idea why the brown lever had come out of the microswitch. I'll keep an eye on it and if it happens again, I might need a replacement dimmer/Odo unit. But for now, I'm a happy bunny.

In cold weather my dash rattles like a good 'un, right at the front where it meets the windscreen. I assume that the dash shrinks enough in the cold weather to allow some play between the edge of the dash panel and something at the front, either the dash brackets under the panel or the windscreen itself. Being a cantankerous old thing, it winds me up even though it disappears when the cabin warms up. That 20 minutes of rattling is most of my trip between home and work, so it had to go.... Well, I found a solution: spongy foam cord on eBay. I ordered a couple of meters of 8mm cord and stuffed it down between the dah and the windscreen. It's compliant enough to push in and fill that gap and hold the dash down, but not solid enough to push on the windscreen and cause any problems. It's also black foam, so it just disappears once in the gap. Two metres is enough to run the cord along the full width of the windscreen with about half a metre spare. The cord is available in different diameters so if your gap is a different size, you can order the right size for your application based on the size of the gap. Don't go massive and jam a big thick cord down there, or it could put pressure on the windscreen or something in hot weather. You need a diameter just big enough to slide into the gap and stop that annoying rattle when it's cold. If anyone has the same issue, the sponge cord is here: https://www.ebay.co.uk/itm/Sponge-Cord-Black-Foam-Rubber-Gasket-Trim-Seal-2mm-3mm-4mm-5mm-6mm-8mm-10mm-12mm/251724620014?ssPageName=STRK%3AMEBIDX%3AIT&var=553228790467&_trksid=p2060353.m2749.l2649

I agree with the others, the only injury you need to prevent in a direct rear-end collision would be whiplash and the seat back and head restraints are the devices that help prevent that happening. There's nothing else that needs to be done as you are not in danger of hitting anything hard once the collision has happened. You're being forced into the back of the seat and the headrest, so you already have a softened impact. I assume if the impact had occurred from an angle (for instance hitting the rear at 45 degrees or so) and the sensors had detected your head was in danger of hitting the side of the car, the side curtain airbags would have deployed.

If the link has broken, then it's a cheap fix. I think I got a stainless (rust-free) replacement linkage off eBay for less than a tenner. Just as long as it can adjust the linkage to the correct length and has the correct mounting bolt size you should be ok. If it's not the linkage but the sensor just needs to be cleaned and refurbished, that's a chap DIY job as well. It gets expensive if you need a new sensor.

I'm one of those people that think the same when it comes to carburettors. It's all mechanical voodoo. I'm a child of the digital age: sensors and computers I can understand. :-) Engine computers are simple: measure the amount and temperature of air going in to an engine and then squirt the correct amount of fuel in based on a table of values. Then check what comes out the exhaust pipe, tweak as required and repeat. Then manufacturers started thinking about adding lots of computers linked by network to control different body, transmission and engine bits and things went haywire... I mean, is a computer really necessary to work the windows? What's wrong with good old switches? You'll love the DiagnoseDan YouTube channel then. All he ever seems to talk about is CanBus problems..

It's not a case of resetting it, you need to check the height sensor that controls the headlamp level on the offside rear of the car. If you are lucky it's just the linkage between the suspension arm and the sensor that has broken and the sensor has gone outside the values permitted by the headlamp module which puts the warning light on the dash. The linkages have a tendency to seize and break. The good news is that you can get replacement aftermarket linkages pretty cheaply. I got a stainless linkage from eBay to replace mine. Access is good so it can be done while you're under the car without needing to jack it up. If you are unlucky, the sensor itself may be faulty, in which case removal, cleaning and refurbishment might get it back working. Or if you are really unlucky, the sensor is shot and you'll need a replacement sensor.

Well, just a bit of an update. After spending the weekend poring over the info Herbie gave me, I've hopefully come up with a diagnostic plan. The Dimmer rheostat connects to the instrument panel module. The module dims the dash switch lights directly. It also sends signals to the other modules regarding the dimmer setting. The thing that threw me for a while is there is also a dimmer cancel signal alongside the dimmer setting signal. More on that in a second. The Nav Screen takes three signals regarding illumination: The illumination signal to say the lights are on (and I assume makes it switch to night mode and dim the display) That comes from the network gateway module. The dimmer signal to say how much to dim the display and switch illumination from the instrument module. and finally the dimmer cancel signal from the instrument module. I spent ages trawling through the details until I found the cancel signal is set by the switch that clicks on the dimmer rheostat. So turn the switch fully clockwise and the cancel signal is set to on. I do know from my initial look with techstream the other week that the dimmer rheostat is working, because the values change from 0-255 in techstream. I now have to check the illuminate signal and the cancel signal to see if those values change to the appropriate values in techstream and then electrically… now I know what I'm looking for that is. When I get chance to hook up the laptop to that car, I'll post an update.

Herbie, many thanks for the info, that's so generous of you. I may need a day or two to digest it all! The strange thing is the exterior lights turn on and off automatically, so I just need to fathom if there is more than one light sensor. i.e. 1 for a/c another for lights and a third for interior lights. I've a lot of circuitry to pore over this weekend. Lol. Or if it's all controlled by one module, what software setting I need to change. 😁

Brouwers: On a car like the RX I don't think there is a direct connection, it's down to the modules to talk to each other in order to make it work. It looks like the module that takes the input from the pot is working because I can see the values change. The problem is that when the headlamps come on, the instruments don't dim, so I need to know if the headlamps are controlled by a different module that isn't talking to the instrument module. If it isn't then I need to know why. Without knowing if the same module controls everything, which module gets input from the light sensor for the automatic headlamps etc. It's hard to diagnose. On a simpler car everything would be controlled by the body control module, but I suspect there are two different modules at play here. The bad news is there are no communication errors reported by techstream. The strange thing is the owner's manual states at night there's an option on the nav display to go to "Day Mode", but my screen doesn't have that option. Conversly, the nav screen doesn't change when the lights come on. Again leading me to think that the module responsible for monitoring the outside brightness and/or the headlamps isn't passing the info to the module that controls dashboard brightness. Or if the dash brightness module has a daylight sensor connected to it, the sensor isn't working. So I can happily twiddle the knob on the dashboard for the brightness, but that module isn't being told whether it's day or night. I think I need a service and repair manual for the car. That way I can look at which module the dimmer connects to and where it gets it's information regarding day/night from.

Ever since I got my RX300, the dimmer on the dashboard has not worked. You can turn it and the lights don't dim. So last weekend I got round to plugging techstream into the car to see if there was a setting that I could change. No luck, there isn't a setting. However, you can see in the live data that when I turn the knob, the module responsible sees it. You can see the value change as you turn the potentiometer on the dash. So the module appears to be connected to the dimmer switch. But I can't get the dashboard lamps to dim. I got annoyed with it last winter and put up with switching the screen off in the centre of the deash, but it would be good if I could just dim the lamps, especially the instrument binnacle.. The light sensor is working, because the headlamps turn on automatically, so if they are supposed to auto-dim, they should dim. Does anyone have any ideas, or even details of which modules are responsible for getting the lamps to dim so I can have a poke around with techstream?

Bad news I'm afraid. The parts of the suspension that hold air have a habit of rusting. When the rust gets bad, it rusts through to the air chamber and causes a leak. Your compressor runs and runs trying to keep the suspension inflated, but eventually it either burns out or wears out and the suspension eventually deflates and stays deflated. The suspension legs are an eye-watering amount of money to replace and unfortunately you'll have to replace at least one of them, although it's best practice to replace suspension parts in pairs. That'll be a £1000+ bill just for the parts I'm afraid. As Herbie says above, it may be time to consider replacing the air suspension with a conventional spring-based setup, because once one shock absorber has gone, the others won't be far behind and you can get a complete spring-based replacement suspension setup for less than the price of a couple of air shocks. Once you are on springs, you won't have the worry of the air shocks. Of course you could replace the air shocks, but at £600-ish a corner (plus a replacement compressor if that's died in the meantime), it's probably as much as the car is worth just to replace the suspension. It depends on how much you like the RX if you want to spend the money essentially buying the car again, or if you want to move on to something else. One of the reasons I especially sought out the spring suspension version when I bought my 2004 RX was to avoid the big bills of the air suspension.

Under the glovebox on a right hand drive car. There's a panel covering the fusebox that unclips to reveal the fusebox. If you look under there you wouldn't know the fuse box is there because of the cover.

If the rear indicators are not lighting up but the front ones are, as others have said make sure the bulbs have continuity across the filament and make sure they are filament bulbs and not LEDs (which are polarity sensitive so only work in one position and need load resistors to work correctly). If you are sure the bulbs have good filaments and the connectors are making good contact and they are still not working, check for 12v at the indicator socket when you switch the indicators on. Obviously one side at a time and you should see the 12v pulsing on and off in time to the rhythm of the other bulbs. If you don't get 12v at the socket, then trace back the wiring. I'd suspect the bulb failure module that monitors bulb failure of all the rear lights. All the light circuits go through that failure module and it's not unknown for the module to go open circuit and not supply voltage to the bulbs, especially if there has been water ingress and it's got into the module. It's a lottery if it goes open circuit if it illuminates the bulb failure light in the dial cluster. Unfortunately I don't know the location of the bulb failure module, but I'm sure someone will come along with the info. :-) The one on my old Supra went open circuit on the brake lights, so I had no brake lights and no indication on the dash that they had failed. Luckily a friend told me they weren't working when I pulled into a car park in front of him. Luckily he wasn't close enough to rear-end the car! In the end I just linked across the input and output for the brake lights and bypassed the bulb failure module.