DIY heated seats - questions

[wondercow2]

If this pans out, I'll try to take photos and make it more of a "mod." But for now I have a question--

Does anyone know how the high/low settings on Subaru or other heated seats work? Is it some sort of voltage regulation, or something simpler?

 

I bought a well-reviewed and cheap seat heater from Amazon: http://www.amazon.com/Wagan-Tech-9738-Heated-Cushion/dp/B000ANOUHQ/sr=8-2/qid=1165549587/ref=pd_bbs_sr_2/103-6958491-3784669?ie=UTF8&s=automotive

It's here, and it works nicely. It's TONS cheaper than other heating pads, and I am very seriously considering installing it underneath my seat cover. But I don't like the idea of using the stock cigarette power adaptor and want to hardwire it, and also do away with the goofy inline high-low-off controls it comes with.

 

I took apart the switch, and it's just a 3-position switch with no voltage conversion anywhere. My guess is that the low setting only powers 1/2 of the heating circuits, and the high does all of them. This is where the question comes in--is this how Subaru heated seats work (ie, the first button press triggers a high circuit, and the 2nd one electronically switches to a low circuit)? Or is there something fancier at work? It'd be nice to use the stock button if possible.

[subiemech85]

look at a classic saab 900, heated seats STANDARD, both bottom and back

 

the newer saabs use a 3-4 positon switch, pressure switch, and thermostat

 

do some searching and you will see

[ron917]

ipd sells a kit with seat bottom and back heating elements, wires, thermostat and switch. They spec it for Volvo 100 and 200 series, but it should work in any car. It's not cheap ($89.95 per seat), but nothing is cheap at ipd - it's probably available elsewhere for less. They sell stuff mostly for Volvos, and some Subaru stuff as well.

 

http://www.ipdusa.com/ProductsCat.aspx?CategoryID=488&NodeID=993&RootID=629

 

Edit: Heated seats have been standard on Volvos at least back to the mid '80s. The 200 series (I've owned 4 of them) had a single position switch. There's a thermostat in the seat element to keep it from overheating.

[wondercow2]

The seat I have has a thermostat for temp control... could the "high" and "low" settings be sending power through 2 different thermostats then?

[Skip]

Getting back to your question, instead of reviewing all cars in history with heated seats.

 

I have been meaning to address the same issue.

Here is what I found in the FSM on the seat heaters.

 

Shows what you said, two elements (high/low).

 

Hope this helps

[wondercow2]

Oooh, great scan! I should be able to use that pin diagram for the switch to use a factory switch then.

[Skip]

You are welcome, 'ave a gidday.

[Tech1967]

There are two ways to regulate current and thus heat. One is controlling additional loads in the circuit, resistors. Two is a solid state chopper circuit, regulated duty cycle. The Subaru seat heater switch changes the circuits so that low runs current through the seat elements in series (higher resistance to ground) and high runs current through the seat elements in parallel (two circuits with lower resistance to ground for each).

[nipper]

Heated seats are controlled in a very simple manner, everyone is over complicating things.

There are two circuits, series and parallel. When the heaters are in parallel, they are at full heat. When they are in series, they are at the lower setting.

 

Now that being said the heater in my seat back is out. Does anyone have a clue how to fix that?

 

nipper

[ferret]

Subaru sells a 'repair' kit which is a new lower AND back heating element. Then an Upholstery shop to replace the elements, unless you are into 'hog ring' and hog ring pliers as well as sewing the element back into the seat cover. Much cheaper to get a used seat at a junkyard.

 

The back and lower pads each have a thermostat as well. Shuts off at a preset temperature as so not to overheat and catch on fire. You can usually fell the thermostat right thru the cover at the rear of the seat bottom, or bottom of the seat back. Since everyone is shaped differently, some people can feel these all the time and complain about the lumps in the seat.

 

The failures I have seen have not been the thermostat, but opens in the coils themselves from the flexing with the seat cover.

[nipper]

Subaru sells a 'repair' kit which is a new lower AND back heating element. Then an Upholstery shop to replace the elements, unless you are into 'hog ring' and hog ring pliers as well as sewing the element back into the seat cover. Much cheaper to get a used seat at a junkyard.

 

The back and lower pads each have a thermostat as well. Shuts off at a preset temperature as so not to overheat and catch on fire. You can usually fell the thermostat right thru the cover at the rear of the seat bottom, or bottom of the seat back. Since everyone is shaped differently, some people can feel these all the time and complain about the lumps in the seat.

 

The failures I have seen have not been the thermostat, but opens in the coils themselves from the flexing with the seat cover.

 

With my bad back now (cry) i want my seat heater to work. Any idea of the cost of such surgery?

 

nipper

[ferret]

When I last had to purchase one of these, over 2 years ago, it was about $200 for the parts, and about the same from the upholstery shop. So it was about $400 to repair one seat. That was then, now.....and depending on the upholstery shop you choose....I'm certain it hasn't gotten any cheaper.