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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?



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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)


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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

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  • 1 month later...

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


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