Electric and heated seats

Jayw13702 · April 24, 2021

My 2014 IS300h is SE spec, as a result I have half leather, manual, non heating seats.

I have located a complete interior that would be a nice upgrade, however its electric, cooled and heated seats.

Sometime ago I asked the question about cars being prewired for things that the car may not have been fitted with, the general consensus was that Lexus didn't do this as it wasn't cost effective.

Today I was doing some work on the centre console and I noticed there was a 6 pin multi-plug that was taped up and is not being used, so I got the multimeter out, there was power to one of the terminals.

Looking at Lexus-tech this appears to be connector K99, the multi-plug connector for the heated seat switches.

Looking at the connector blocks that are listed K99 is the 6 pin connector listed here

There are 30A fuses in the power seat fuse locations and 15a fuse in the heated seat locations.

Next job will be to take out the seats, lift the carpet and see if there are any multi-plugs attached to the wiring loom in the area of the seats

my current seats have 3 multi-plugs on them, does anyone know how many connectors an electric operated and heated seat will have?

200h · April 25, 2021

the ventillated seat fans are controlled by the fan speed sliders

the faster the cabin fan the faster the seat fan.

here is a video of the removal of the centre console

fast forward to 4.35 and you will see the back of the heated & ventillated

switch panel showing the plug and wiring colours.

( the guy forgot to remove the cross head screw by the gear selector)

Jayw13702 · April 27, 2021

Thanks for that, the plug looks similar but most importantly the number that’s stamped on the plug is the same number listed in the wiring diagram.

the seats are coming out this weekend so we can get the carpet up and look for the looms for the heaters and electrical motors

Jayw13702 · June 5, 2021

it took me a little longer that planned but at last I have found out the answer........

My car is prewired for heated seats. I took the seats out this weekend to clean the interior and looked at the multiplugs.

the seat, a bare multiplug

the loom that's on the car, with all the correct wiring in place

so now the hunt is on for a switch, seats and centre console trim

200h · June 5, 2021

here is a link for a black seat , when i've gone through the images

i have seen the heated seat switch

there are 2 seats available

https://www.synetiq.co.uk/parts-breaking/details/front-seat-lexus-is-mk3--ave30--2013-to-2018-300h-saloon-passenger-side-warranty/-/387845/

Jayw13702 · July 7, 2021

Well we bit the bullet and bought an interior.

thats 8 foot tall by the way and about 95% of an entire F-sport interior.

it was filthy, but having cleaned up the front seats they literally were plug and play.

So I’ve gone from manual half leather to electric operation and heated half leather sport seats, I so with I had done it earlier

this was the seats when I took them out of the container.

there’s quite a lot of things in the crate I’m not going to transfer over to my SE though

MartinH · July 7, 2021

That's a pretty radical modification. Well done!

Jayw13702 · August 8, 2021

The front seats were plug and play, the rears were a little different................

The standard seats in a SE are solid one piece back, the F-sport seats are split rear seat.

because the stitch pattern is different between the SE seats and F-sport I had to put the rear seats in if I were to keep everything looking uniform.

In order to change the rear seat from a solid to a split rear seat you need the following:

Both parts of the split rear seats
Rear seat edges
Seat base
LHS seat buckle
Both seat back catches
All the plastic trim that sits behind the split seat backs.
Rear parcel shelf (even this is different)
As many bolts as you can remove from the donor car

The easiest way of doing this is to clear out the interior of the old parts. When I first looked to see if this was possible I couldn't see any bolt holes for the spilt seat brackets. Lexus cover any unused boltholes with black sticky tables that are about the size of a £2 coin. Having figured out where the brackets should sit it was easy to find the threaded holes.

The rear parcel shelf needs changing as the SE spec cars have the rear seat belt mounted on the rear parcel shelf, the cars with split seats have the belt in the seat itself. Also the LHS seat buckle needs to be changed as the SE one is part of the central seat belt assembly where the other one is a solo part. Getting the rear parcel shelf requires both of the C pillar trims removing as they lock the parcel shelf into place, also the high level brake light needs separating from the parcel shelf and disconnecting

Removing the SE rear seat back reveals a metal X bracket that's bolted to the body and acts as brace to stop anything moving from the boot to the passenger compartment. the split rear seats are metal backed and so do this automatically. The bracket needs to be removed.

Still working inside the car all the plastic trim that sits around the back seat aperture needs to be fitted, the split rear seats can now be fitted, once they are in then the seat edges can be fitted as well and the seat bas can go in as well.

Moving into the boot, the SE boot carpet covers the seat back and this needs to be trimmed down so that it sits within the split seat trim panel, a good craft knife will cut the carpet down to size.

It took me a few hours to do, with the exception of some trim removal tools there was nothing else out of the ordinary needed.

its one of those jobs that only easy if you have all the parts, it anything is missing it just won't work

Mincey · August 9, 2021

You are a legend @Jayw13702 - is there anything you cannot do? 🙂

route66 · August 10, 2021

On 8/8/2021 at 10:13 PM, Jayw13702 said:

Removing the SE rear seat back reveals a metal X bracket that's bolted to the body and acts as brace to stop anything moving from the boot to the passenger compartment. the split rear seats are metal backed and so do this automatically. The bracket needs to be removed.

Is this structural rather than just something to prevent things moving in to the passenger compartment? I ask because a "X" has gaps ...

Having said that, with standardised production being the norm, I guess it would make no sense to have this any different.

Jayw13702 · August 12, 2021

On 8/10/2021 at 4:46 PM, route66 said:

Is this structural rather than just something to prevent things moving in to the passenger compartment? I ask because a "X" has gaps ...

Having said that, with standardised production being the norm, I guess it would make no sense to have this any different.

I believe it’s to stop things from entering into the passenger compartment, whilst it’s an X shape it covers a good 80% of the aperture.

you can’t see the brace as it’s covered by carpet in the boot

Jayw13702 · August 12, 2021

On 8/9/2021 at 8:33 AM, Mincey said:

You are a legend @Jayw13702 - is there anything you cannot do? 🙂

Thank you, it’s all about taking the time to figure out if things will work.

On and off I’ve been looking at this upgrade for about 12 months now, it all fell lucky when I discovered the wiring looms and then the complete interior.

paulrnx · August 13, 2021

12 hours ago, Jayw13702 said:

Thank you, it’s all about taking the time to figure out if things will work.

On and off I’ve been looking at this upgrade for about 12 months now, it all fell lucky when I discovered the wiring looms and then the complete interior.

Great result and well done 👏