Heated seats not working

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Dec 11, 2009 | 07:13 AM

#16

mkaye

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Joined: Aug 2007

Posts: 83

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From: ON

OK, the aftermarket heater wasn't a good choice...
i replaced the back with the aftermarket, it is only 2 wires, while the existing heater had 2 elements, so 3 wires
i tried connecting the 2 wires from the seat heater together (connected them in parallel) and then thru the new back heater (series) to 12V
the back got nice & toasty, but the seat never seemed to heat up
i tired the back in series with 1 element of the seat heater and it dropped 10V, while the seat only got 4V, so not a good match
i decided to repair the original back heater & now i just have to get the seat out again & replace the back heater.....

mark

Dec 11, 2009 | 08:33 PM

#17

eles400

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Joined: Nov 2009

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From: bc

my 92 ls400 the drivers seat heater works only a little bit, the passenger seat works perfect, what can be done?

Dec 11, 2009 | 08:49 PM

#18

solok25

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From: colorado

if relay or fuse was blown would the heat buttons green light still come on mine does but driver seat cushion dont wk and pass back dont wk

Dec 12, 2009 | 06:34 AM

#19

mkaye

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Joined: Aug 2007

Posts: 83

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From: ON

Quote:

Originally Posted by eles400

my 92 ls400 the drivers seat heater works only a little bit, the passenger seat works perfect, what can be done?

there are 2 elements in each heater wired in series with the other heater
so basically 2 heaters in parallel
if 1 breaks, then you get 1/2 heat in that seat
it's not rocket science, but time consuming to pull the seat and peel the leather back enough to remove & fix the heater
my mechanic gave me a tool & hog ties (the clips that hold the leather), but i found i could open the existing ones & reuse, but tie-raps would have worked too

there are 2 3-pin connectors in the back of the seat, with an ohm meter you can determine which heater element is open

mark

Dec 13, 2009 | 01:10 AM

#20

Rollaboy

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From: Copenhagen

Both driver and passenger seat is out on my 90' LS. It sucks now when its getting winter.

Is it possible to take out the seats and take the leather off, find the problem and solder it? Or is it not possible to fix by yourself?

Its not fun to take out the seats when its so cold now, so it would be nice to do all the work and make it work the first time instead of taking the seats out and install again several times.

Dec 13, 2009 | 05:53 AM

#21

Kansas

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Joined: Jan 2004

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From: Kansas

Quote:

Originally Posted by Rollaboy

Is it possible to take out the seats and take the leather off, find the problem and solder it? Or is it not possible to fix by yourself?

It is not necessary to remove the leather to identify the problem. There is a detailed diagnosis procedure for the seat heaters in your car. The procedure for my 00 LS is a little lengthy but it is easy to follow and involves testing the pins on connectors and relays for continuity and resistance, testing the seat heater thermostat with some sort of heating device, etc.

You could replace the heating elements and still not solve the problem. Obtain the diagnosis instructions for your car and follow them!

Jan 20, 2011 | 11:13 AM

#22

gm991

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Joined: May 2010

Posts: 33

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From: MA

Quote:

Originally Posted by solok25

if relay or fuse was blown would the heat buttons green light still come on mine does but driver seat cushion dont wk and pass back dont wk

anyone know the answer to this???
My drivers side heater doesn't get hot when I push the button.

thanks

Jan 20, 2011 | 12:18 PM

#23

SRV1

Driver

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From: NY

My 96 has the same problem, the drivers seat does not heat up at all not the butt or the back. I never tried the passenger seat. The buttons both light up though. So if they are wired in parallel, then if one is bad then other one should work, correct?

James

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Jan 20, 2011 | 01:05 PM

#24

SRV1

Driver

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From: NY

Wiring diagrams and TSB

Here is the wiring diagram (1996) and the TSB for the 95-2000.

James

Attached Thumbnails

Heated seats not working-heated-seats-diagram-1.jpg

Heated seats not working-heated-seats-diagram-2.gif

Attached Files

heated seats TSB.pdf (446.1 KB, 983 views)

Jan 20, 2011 | 03:51 PM

#25

randal

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Joined: Nov 2009

Posts: 486

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From: IN

Quote:

Originally Posted by SRV1

According to the schematic, you are correct, SRV1. It does appear as though each heater switch directly controls the current through the respective seat. So, if you see the heater switch light on, you do not have a fuse or relay issue. Just a broken seat element or possibly a connector gone bad between switch and seat. Possibly a bad ground on the seat element.

Last edited by randal; Jan 20, 2011 at 03:53 PM. Reason: clarification

Jan 22, 2011 | 12:37 PM

#26

gm991

Driver School Candidate

Joined: May 2010

Posts: 33

Likes: 1

From: MA

thanks SRV!
looks like I have a bad heater in the seat, switch light turns on when I press the button.
just sux its the drivers side and not the passenger side thats broken.....LOL
Guess I will have to deal....

Jan 22, 2011 | 05:27 PM

#27

deanshark

Pole Position

Joined: Dec 2009

Posts: 3,278

Likes: 317

From: ct

Quote:

Originally Posted by gm991

I think there is also a relay under the seats that could have gone bad.
I was gonna look into fixing mine one day, I unbolted the seat, tilted it back, saw ALL the wires,

bolted it back down. lol

Jan 22, 2011 | 07:12 PM

#28

randal

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Joined: Nov 2009

Posts: 486

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From: IN

Quote:

Originally Posted by gm991

Depending upon how the switch light is wired, I suppose the switch contacts could be shot. Next step would be to pull the switch and check directly there.

Jan 23, 2011 | 05:19 AM

#29

Kansas

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Joined: Jan 2004

Posts: 3,595

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From: Kansas

Quote:

Originally Posted by deanshark

I think there is also a relay under the seats that could have gone bad.
I was gonna look into fixing mine one day, I unbolted the seat, tilted it back, saw ALL the wires,

bolted it back down. lol

As I mentioned earlier in this thread, there is a diagnostic procedure for the seat heater system for each model and year. The diagnostic procedure for my 2000 LS400 is four pages long and mainly involves testing pins on connectors for continuity or resistance.

Follow the seat heater diagnostic procedure for your car and there will be NO GUESSING as to what the problem is.

Dec 2, 2012 | 06:37 PM

#30

Shmee

Lexus Test Driver

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Joined: Dec 2007

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From: Victoria, BC. Canada

Kicking this back up as i'm about to order the service manual(s) but do i need the service/repair manual, the Wiring diagram manual or both?
Also, does it matter if it's year specific or will a different year from te same chassis work?
eg: i have a 96, will a 97 work or will there be enough differences that i'll be chasing my tail?

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