DshngDaryl

Hey Jonnycake,

I read a post of yours about how you and Habious tried to fix your seat heater.

The lesson I walked away with was to put a meter on the two ends and see if there was continuity. If there is then the grid system is in tact and if there is not, then you need a new heater grid.

Looking under my seat I see two connectors. Is there a third one I don't see. Off the top of your head, can you tell me which one is the seat heater? The one closer to the center of the seat, or the one at the back of the seat?

It has been awhile since I read the post and probably even longer since you wrote it, but any tips you can throw my way would be appreciated.

JohnnyCake

Wow, I've never been in the title to a thread before -- I'm famous! LOL

We never did that as I recall. We did a lot to the rotary switch by the gear shift to make sure that wasn't the problem (i.e. easy fix). People have replaced the actual grid, but it is hugely difficult. People have replaced the entire seat itself, but then it doesn't match the rest of the car and it is also very expensive.

Is your failure intermittent or always? Mine is intermittent, although seemingly always when I really want it to work.

If you find a solution, please circle back and post here. Especially since I like to drive until it is ABSOLUTELY too cold out, I really miss the seat heater.

DshngDaryl

That's a bummer, but thanks for replying anyways.

When I turn on the rotary switch, the light goes on which leads me to believe all the fuses are working.

However there is no heat in the seat, which makes me think the grid is bad. The questionable thing is there is no heat in the backrest either. I think it is odd that both would be out, so I wanted to get some advise from you.

mrblister

I have a 2004 gx470, This may help. My drivers side seat heater bottom was warm not real hot. My drivers seat back was cold no matter what
It was repaired under warranty and they replaced the seat grid for the seat back not the bottom. It seems on my gx470 the grids worked independently of each other . Truck was under extended warranty and was repaired cost was approx. $ 675.00. That's what the parts and labor were that they billed lexus plat warranty.

Harold57

A wiring diagram ought to show how the heaters are hooked up if someone has a copy of that.

Harold57

Well, here is one but I can't decipher the symbols.

DshngDaryl

Thanks Harold, that is very helpful.

So can I send a thought your way? if I read the diagram correctly, I should see a harness under the drivers seat with a black and yellow wire, a black wire and a red & blue wire. All should have power on them with the ignition on. There is a white & black ground wire. Most likely the black goes to the back and the black and yellow goes to the seat (or vice Versa)

Does that sound right to you? (or anyone else)

JohnnyCake

Does anyone know if our seat heaters are a single grid system? FWIW, I have the same symptoms as DashingDar -- switch good, no heat back or bottom.

P.S. Habeous, who is about the smartest person I know, says this is almost certainly a break in the heating element wire.

DshngDaryl

Does anyone know if Techstream can check the seat heater system?

Bgw70

i don't think it can. Using the wiring diagram you should be able to check voltage and since a heater is an inductor, you should be able to ohm out the heating element.

does either seat produce heat?
Standby for the service manual checkout.

Bgw70

Use the wiring diagram Harold posted in conjunction with the following check out instructions.

Harold57

Close. I suspect that only one of them will have power until the control turns it on. I think that S24 & S25 are the controllers between the seats. I suspect that the BLK & BL/YEL wires are the returns for the heaters and the RED/BLU wire is the power source for them. It appears as if the seat and seat back heaters are separate, but I'm not sure. I do seem to remember some in the forum in the past mentioning that their seat back didn't work but the seat did (or visa versa) but am not sure about that since I've slept a few times since then.

The best way to confirm any of this will be to take a meter to the connectors and measure them. Bgw's instructions will help there the most. Good luck and let us know what you find out.

DshngDaryl

Thanks BGW.

I haven't done anything yet because I have to unbolt the seats to get to the boxes and wires underneath them.

After reading the diag procedure, I see I can test the grid system by taking off the back of the seat. That seems like an easier way to do some tests.

Of course Occams Razor says I should test the connections first, so I will PROBABLY do that.

Harold57

It would be nice if it is only a connector that has come loose.

JohnnyCake

I was interested in the skematic that BGW posted and the sub-assembly mentioned in there. I previously had the opportunity to "borrow" a switch temporarily and swapped (thanks Habious) so determined that that was a known good. I suspected a break in the cushion wiring like everyone has, but the opportunity presented itself to temporarily swap in a known good seat assembly. Unfortunately, that did not help so now I think I have conclusively tested everything it could be and, like everyone else, have the dreaded seat cushion wiring break.

Very sad. It's way too expensive and too difficult to replace so its another winter with a cold a**.