LS460 heated seats

[GB10]

Hi all,

Both my driver and passenger heated seat have started to misbehave at what appears to be the same time; they will both function correctly for 5-10 minutes after which the fan continues to run but the heater element cuts out.

The green operation LED illuminates as expected on both seats and I can hear the under-seat relay engage in response to the dial.  Whilst I accept the element will probably require replacement, the fact that both seats have failed simultaneously encourages me to remain optimistic and hope there is a failed over-temperature thermocouple or equivalent in the circuit before the heater element, but cannot find any schematics that detail the circuit to confirm or deny this theory.

Does anyone have any experience with the heated seat operation in the LS460?  I would be extremely grateful of any schematics or photographs of the underside of the seat and the related components before I commence disassembly on the weekend.

If the element does indeed require replacement, has anyone successfully completed a DIY swap?  I have found numerous posts relating to other models with similar problems, but very little specific to the 460.

Any help much appreciated.

[SH20]

Be aware Simon, the  seats require the negative terminal of the Battery to be disconnected if your remove either front seat.  You must wait at least ten minutes before disconnecting the yellow block terminal after you disconnect the negative terminal to allow the circuit to discharge.  This precaution will stop the possibility of the seat air bag  going off as you undo the yellow air bag block connector under the seat.  Four floor bolts and two other block connectors plus the seat belt anchor bolt in the side cushion will allow your to remove the seats but watch out they are very heavy.  Sorry can't help with your main issue.  I do know the leather seat cushion is a time consuming job to remove if you have to replace the heating element.

Steve

 

 

[GB10]

SH20,

Thanks for your response and the photographs; it looks like there is a great deal of kit crammed into very little space!  I didn’t even consider the airbags, that could have been a costly and painful mistake.  I will observe the 10 minute wait as suggested.

Further research suggests that each seat is also fitted with an air filter, so it’s feasible that this has not been changed since new and is now blocked, reducing airflow and the heater is cutting out due to an over temperature condition.

I will not have an opportunity to dismantle the seat until the weekend, but will update this thread with my findings once done.

 

Thanks again.

 

[mr2lad]

What ever your doing STOP.... These symptoms are the same I had on my LS600 heated seats... Warmed up for 5-10 mins then just blew cool air....

as car was still under warranty I put it into Lexus they diagnosed a knackered heat element and replaced at a ......... Go sit down first before I tell ya.. COST of £1350 plus VAT ps the  element is not a separate piece you have to change leather as its intrigated with element and no way to change seperatly

big write up I did on this last year on the forum

now that I've got you suitably shocked here comes the sweetener and light at the end of the tunnel,

after changing my seat leather/element I got LS back and tested seat and it still didn't work so did a bit of research and contacted Lexus and asked if they had checked the relay for heated seat.... Guess what they hadn't and it only cost £20 ..so at end of day I received a brand new leather drivers seat at a cost of £1350+vat because they failed to diagnose problem properly

- ps it was only my drivers seat that had the problem, each seat has its own relay for heated seat ... So check this out first

 

 

[GB10]

Just found and read through your thread on this, (thanks for bump.)  As you say, the symptoms match perfectly.  Poor show indeed from the dealer, but this sort of approach seems to be commonplace – what can we swap that will take the minimum time and effort on our part that will probably fix the issue presented?

Not having the luxury of a warranty or a spare £1350 per seat the official Lexus route is not a realistic option for me; I enjoy tinkering and can’t stand things not being right so am quite prepared to have a go at this sort of thing myself.  I assumed that there would have to be some form of thermostat to regulate the element and either a secondary over temperature cut-out device or the functionality would be built into the control device.  As the relay is engaging in response to the control on the centre console I had dismissed it as the probable cause and focussed on the element itself.

Do you happen to know the part number of the relay unit?  The entire seat looks like it needs to be removed to gain access and I do not really want to have to remove the seat twice.

I have a Toyota dealer less than 10 minutes from my house but the nearest Lexus dealership is a good 45 minutes away, so I called Toyota naively believing they could assist with obtaining the part (and book a full service at the same time.)  As soon as I mentioned the ‘L’ word, they would not discuss any parts and refused to accept any servicing requests, insisting that it goes to the Lexus dealer…..

I’m thinking the exact same relay is likely to be fitted into a Toyota branded vehicle, so if I had the part number I could call back quoting that and they would be none the wiser, and save two hours of my day.

Should the under seat fan spin up when heat mode is selected?  At the minute the fan only works on ventilation mode, is that the same on your 600?

Thank you for your input – much appreciated.

[mr2lad]

Can't help with part No unfortunately but if I was you I'd speak with your nearest Lexus dealer ... My local dealer is 4hrs away and my Toyota dealer is always happy to help when I've put any of my Lexus thru to them 3x now once with my LS400 next my GS450h and even my LS600 has been into them to get a brand new key reprogrammed and no hassles at all

[steve2006]

Having looked at the exploded diagram parts list although the element is shown as a separate part it is not available as such but comes complete with a new seat base priced around 2 grand !!!

Can't find a relay on the diagrams but if you can locate it in the car by listening for the click and let me know the location I'll look it up for you.

I can't believe 20 years on from the series III LS400 that there are still problems with heated seats, maybe an option to find a scrapper and buy the seat, strip it down and use the parts to repair yours unless you get a matched one in the same condition.

 

 

[GB10]

Time wasn’t on my side over the weekend, so annoyingly very little progress was made.

I planned to order a couple of these heater control relays at the same time as booking a service.  (I had to call three Toyota dealers before I was finally offered routine servicing, it was well worth persevering through as the price I was quoted was half that of Lexus.)

Discussion of the relay somewhat flummoxed the girl on the service desk, and whilst they promised to look into the part in question and call back with part number and cost I struggle to remain optimistic – I think they will need to be quoted a specific part number, or I need to contact the Lexus dealer.

 

Steve2006,

The driver and passenger seat each have their own relay, located directly under each seat.  I can hear the contacts make and break on each seat when operating the control on the centre console.  It sounds as if the relay may be located towards the front of the seat rather than the back but I may be wrong.  Even with the seat raised to its uppermost position there is still very little room to identify anything.

Parts for these cars seem quite scarce when moving away from the main Lexus parts desks, even eBay has little to offer outside the USA – does another resource exist that I am unaware of?

For the approximate cost of £20 per side, I think it’s worth buying a couple of these to swap over and if that then still does not work, I’ll look into obtaining complete seat assemblies to dismantle.

 

Thanks to everyone for their help so far!

[cruisermark]

a note on toyota servicing lexus - our local dealer (steven Eagell) will happily do it and charge toyota landcruiser V8 pricing which starts at £259 for a service

[GB10]

Exactly the price I was quoted!

No call back regarding the relay, but I can't say I'm surprised.  I'll try my luck with the Lexus dealer.

[GB10]

I thought I might be getting somewhere with this...I was wrong.

Whilst searching for another unrelated issue, I came across this website, and eventually found this TSB.

Confident I was armed with the right part number I contacted Lexus requesting cost and availability, thinking that if the part in question only cost mr2lad £20 last year I might expect to pay closer to £30 now.

£332.00 each - two required per seat.

I really hope this is an entirely different item and the relay still exists but under an unknown part number.  The parts assistant, whilst very helpful, was unable to find any other components in the seat heating system, and the TSB does imply this part is the cause of my problems.

Is there an alternative way to approach this?  Tearing apart old seats from donor vehicles is looking increasingly likely....