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Interesting, thanks. What I have noticed is that if I do get the clunk as I set off, I'll probably get it at some point while driving, too. Whereas, if I don't hear it at first, the journey will probably be trouble-free.

Thanks. I usually notice it when setting off forward due to parking position at home, I'll have to pay attention when it's parked elsewhere.

Could it be related to the mechanism that locks the wheels in 'P' mode? It didn't do it at all this morning, so it's definitely intermittent.

Hi, Our RX400h has started making a horrible clunk from the rear when first setting off, regardless of whether it had been sat with the parking brake engaged or not. Often, we'll hear a squealing sound too for the first few seconds of driving. Sometimes we'll hear that clunk or almost a pop a few times on the trip too, but other times we won't get it at all. A year or so ago we were told we might need to replace a hub a some point - apparently it's near impossible to replace just the bush. I wonder if it's that, but hope it isn't as apparently it's a really expensive part. Any ideas? Thanks

I had forgotten about this thread, sorry guys! But here's the conclusion for anyone reading with a similar problem: The drain was caused by an iPod connector in the glove compartment! Apparently it's not a factory fit, but an accessory that gets installed at the dealership when the car is first purchased. I didn't even know it was there. As soon as it was removed, the drain dropped down to normal levels 🤦🏻‍♂️

Oh, that looks interesting - I'll have a good read through. Thanks!

Update: The gear selector issue is fixed - it was a seized ball joint on the selector unit. Once freed, it slots into position smoothly and every time. The drain issue hasn't been so simple unfortunately. It was traced back to an ECU fuse that when pulled drops the drain down to a more acceptable 0.04 amps. That fuse has 30+ modules associated with it apparently! I could take it to an auto electrician but the problem is that there's water getting in somehow and so even if the bad module were located and cleaned up/replaced, this could easily happen again. This problem started after about three days of heavy rain. The passenger side footwell is damp under the carpet, and there aren't the usual signs of water running down pillars etc.

Thank you. Yes, I see your point and that will be the next step if the garage can't sort it. By the way, this is an independent specialist and not Lexus, but your point certainly still stands. I still get PTSD from the last car, so I hope it goes differently this time. That said, perhaps I'm being a little unfair comparing a Peugeot to a Lexus of the same era 😁

I ended up taking it to a Lexus specialist! However, they've yet to find the cause of the drain which is apparently around 1 amp, so I'm starting to get a little worried. Especially after scrapping our last car due to electrical issues that couldn't be diagnosed... Yeah, that was it exactly! It seems that I need to calibrate the sunroof and passenger window every time it goes flat. I had no problems with the gear selector after a one hour drive last week, so could be voltage related. However, I have noticed on occasion that the selector is like stirring porridge, so there could be a mechanical element to the issue too.

I couldn't get the lid off at first, but there's a catch around the back to release it

The battery finally charged and its voltage is 13.20, so something must be draining it heavily...

That's a great video, by the way!

Oh, something else I noticed was that the sunroof wouldn't operate automatically - I had to hold the switch down and release at just the right time to get it to seal (overshooting starts to open it via the tilt mechanism). Before all this started, I could press and let go and it would automatically stop at the perfect position.

Thanks for the table. I think it must be draining I just checked it again 15 hours later and it was down to 11.35V - a brand new AGM battery. According to the table - and if the multimeter is to be trusted - it's almost drained the battery completely in this time. The locks, motorised accessories and gear selector worked perfectly, however. I started the car again and the voltage across the terminals was well over 14V while the hybrid system charged the battery, then once I turned it off I measured it dropping from 12.26 to 12.13 over the course of a few minutes - I could see it dropping. I think I'll pull and charge the battery to 100% to get a baseline on this meter.

I went out to check the car again and measured the voltage at the 12V battery terminals as 11.82V. It's a rubbish B&Q multimeter so not sure how accurate that was, but I figured it may come in handy for relative measurements to see if the new battery is being drained like the old one. To answer your question, after that I was able to start the car by holding the selector all the way forward while I turned the gear, and was then able to shift into drive and reverse and move the car. I got a new error on the nav screen and I wish I had recorded it - I think it was something about about the P position and it also warned of how the battery wouldn't charge in neutral. After moving through the gears a few times, I turned the car off and back on again and this time it would go into 'P' every time without me having to hold it?! I still don't trust it, but I wonder if something has somehow reset/recalibrated. Putting it in park engaged the parking brake as expected. Finally, I turned off the car and measured the voltage at the battery again - this time it had jumped up to 12.5V. I don't know if that is significant, but I wasn't expecting such a big jump considering the battery is brand new and had even been topped to 100% before installation. I wish I had measured the voltage when it was installed this morning, but I'd borrowed the multimeter this evening. I'll be checking the voltage every day without using the car to see how it's holding up and welcome any other checks I can do.

Good question. I'll see if it wants to roll when physically in the park position, although it still refuses to go into 'Ready' mode unless 'P' is lit when I turn the key.

Hi, As the title says, I can only get 'P' to light on the dash if I hold the selector as far forward as it will go - the moment I let go of it, 'P' disappears and the car is in some sort of limbo mode where nothing is selected. This means I can't leave it in park, and I have to hold it foward to be able to start it; not sure how long that will last before I'm unable to select it at all. Backstory: I just replaced the 12V battery after it went flat three times in a row to the point of being unable to unlock remotely. A couple of days before I replaced it, it took 10 mins to get it into 'P' to start the car, nearly stranding me. I didn't seem like even holding the selector forward would get 'P' to light up, so after replacing the battery it seems like the behaviour has changed slightly, but who knows. I also had a few moments where 'D' and 'R' were problematic before the battery replacement, but that seems to be gone now too. Can't say for certain though.

Further update: I got the new battery fitted this morning - the Exide was again completely flat after just a few days, but inconclusive as to whether this is due to it being ruined, or something draining it. I hope it's the former, as I don't want to kill this new battery - especially at the price! However, I still have the gear selector problem I can only get it into 'P' to start the car if I hold the selector as far forward as possible - then the light appears on the dash. If I let go of the selector, the 'P' disappears and it's sat in some sort of limbo between modes, with no letters lit. This behaviour seems different to when I had the dying battery - it didn't seem to matter if I held the stick forwards at all then. Anyway, I'll make a new thread on this issue as it's probably unrelated to the heated seats!

I do have an update! The short story is I found the fuse on Sunday - it was the only yellow 20A one in the smaller of two fuseboxes in the engine bay (the one at the rear right when stood looking at the front of the car). This disables the heater in both seats. The longer story is that my two-year-old 12V battery (Exide Premium EA456) had gone flat twice in a short period of time - flat to the point of not being able to unlock the doors remotely. The first time it happened, the car had been sat for over a week in the freezing cold, and a booster pack got it started easily. I took the pack with me, but after a short trip the battery had enough charge to get me back again. Even so, I put it on my Ctek smart charger and reconditioned it once I got home. When finished, the charger reported that the battery could hold charge, and so I put it back in the car. This time, it went flat just a few days later. I put it on the charger again, but didn't put it back in until I knew I would have time to look at the heated seats, wondering if it was the faulty one draining the battery. Again, the charger 'reconditioned' it and reported it as holding charge. Anyway, after pulling the fuse, I was hoping that the battery would be okay - and it was for a day - but the following day I had issues with the gear selector - there were a couple of times that it wouldn't go into 'D' or 'R' - I thought it did, but then the accelerator did nothing. I managed to get where I was going (short trip, again), but then I couldn't get it into ready mode with the dreaded 'Shift into P to start' message on the dash. I read a lot of forum posts suggesting that the 12V battery is to blame and did manage to get it to register 'P' and start with the booster pack, although that could have been coincidental. I've ordered an Optima Yellow Top now, which I'm hoping will fix things. I'm just concerned that something other than the heated seats may be draining the battery.

Sorry, that bugs me too! I had meant to reply to at least thank you for the information (thanks!), but got distracted. I've not had chance to look at the car yet, but I hope to after Christmas and will update when I do.

Hi, The driver's seat in my 400h heats to backside-burning levels whether I want it to or not. Which fuse or relay should I be looking at? Thanks

I got that from the sticker on the door jamb, which states 2.2 or 2.3 depending on what appears to be the speed rating. I've put 2.3 into these new ones and it rides very nicely. I love putting good quality tyres on a vehicle. It makes such a difference, and the CrossClimates are some of the best I've found.

Thanks, I will. It's got around 160k on it, but hides it very well.

True, the climate was set to 22c and it was cold out. Thanks for the driving tips. I'll try them next time I go out.

I got the tyres fitted this morning. It feels a lot better in ride quality and steering! It stays centred a lot better now, although I'm still going to get a four-wheel alignment done once I've had the suspension checked over. I was a bit disappointed with the fuel economy; I got around 22mpg for the trip to the fitters and back (10 miles roundtrip through a town, mostly 30mph roads with light traffic). The hybrid battery showed that it was nearly full the whole time.