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seat heater troubleshooting

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This past spring I picked up my 1998 Legacy OBW... now that it's gotten cold outside, I was gonna impress a friend with my seat heater. After 10 minutes or so I asked him if it was warm enough. He told me the bottom wasn't warming up at all but the back felt nice and toasty. So today I took my 14mm socket and my multimeter out to the car to see what's wrong with it. First thing I did was verified that it was getting 12V when the switch is turned on. Check, 12V, got it. Now I've got the seat out to make sure the wiring is in good shape. Everything looks good there. (I even recovered 85 cents the previous owner had lost in and around the bolt points :) ) I started checking ohms since there should be some resistance there from the heating stuff, but I'm just confusing myself. Can anyone tell me what I should check and what I should expect to find? I don't think I'm up to taking the seat apart and taking the leather off so if it involves doing that just to troubleshoot, I'll probably just put it all back together and try to forget about it.

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Well, most likely there is break in the heating element. To fix it will require stripping the seat, and soldering the element back together. My cloth seat trim was easy enough to get off and back on. It's stretched tight and held on by re-useable copper clips.

 

 

Oh, I found 100 Danish "Crowns" under my seat runner, that's roughly 12 dollars!

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Just guessing, but one reason you may be confusing yourself is that , if like my '03 OBW, you have a hi-lo position switch, the low position runs the back/seat in series, the high position runs them in parallel. If it is 2 position and neither element heats in 'lo' then most likely an element is open. But if they work in 'lo' and you lose one on 'hi' could be the switch or - I dunno - a fuse somewhere? If yours is single position I dunno, try to compare the working seat to the non-working one.

sounds kinda tricky - good luck

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I definitely didn't think about the parallel/series issue. I'll have to check into that more. We only had it on high and that's when we got the back heat only.

 

100 Danish Crowns huh? That's way cooler than 3 US Quarters and a Dime. :cool:

If I do get brave enough to take the seat apart, it looks like I'll have to separate the bottom from the back. When I take them apart, are there any springs in the recliner mechanism that could go flying? Also, do I need to note the position it's in and make sure I put it back together in the same position? It's stuff like that that scares me.

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i have the same problem. i did some digging, and found that it is a series/parallel arrangement. on low, both elements are in series. on hi, in parallel. i forget what the pinout of the connector under the set is, but if you check one side against the other, it will not match. you can also see which pins you get voltage from as you move the switch.

 

i called one dealer, and they wanted something like $250 for a set of elements. i later found just the seat bottom element on 1stsubaruparts.com for $100. i started taking the seat apart, then decided that it doesn't really matter that much to me. i am planning to swap it with the one from the passenger seat at some point, as i ride alone 99% of the time...

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I've got the same problem. The driver's seat bottom has been broken since I bought my 98 OB Wagon used 3 years ago.

 

Is it simple to swap the driver's side bottom with the passenger side? Also, has anyone had any luck with re-soldering whatever is broken down there?

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Make sure you look carefully at your seats before you start tearing them apart.

 

I was going to swap bottom cushions (due to wear) on a Civic years ago. However, they were mirror imaged. The seat was not symmetrical about its centerline. (Eg, recliner handle on outside, seat belt buckle on inside, different shape outside to inside.) This might apply to attachment points, etc as well.

 

Study it carefully. I'd be surprised if you could just swap them.

 

Commuter

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It does sound like you do have a broken heater in the seat.

 

As far as getting a resistance reading I would guess you should see something less than 1 ohm. You should be able to compare readings from the back and bottom connections, if you can get a reading from the bottom section. You could also use the drivers seat for a reference.

 

It would be nice to know how much power these seats need to work. I would guess about 20 to 30 watts.

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as i recall, for a good seat, the resistance was 8 ohms on low (with them in series), 4 ohms on high.

 

as for switching them, you would have to take the fabric/leather off, then switch the element - the cushions are not the same on both sides. and there is no guarantee that when you open it, they will be the same element, but i would suspect that they are.

 

as for repairing the element, if the problem is somewhere in the middle, i was a little hesitant to make a repair. it is surrounded by semi-flammable materials, and under very important parts (my keister). i think i was going to spring for a new element, but i haven't found it to be that unbearable...

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Your resistance numbers make sense Skip. You must be right. My estimate of less than 1 ohm is too low, now that I do a little mental calculation. If things were like I was thinking, a person may not be able to stay seated very long if you left the heater on. They would really be in the hot seat.

 

Thanks for the info.

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Resistance readings seem off for series-parallel arrangement: If in series you get 8 ohms you can reasonably assume the elements are about 4 ohms each, bottom and back. This would be confirmed by a parallel reading of 2 ohms. This would be the MAXIMUM parallel reading with any ohmic combination of back and seat.

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I can't shed any light on this particular seat heater problem, but one thing to keep in mind is that the elements are delicate and are most often broken by someone kneeling on the seat cushion. I have threatened my children with disinheritance if their knobby knees ever touch the seat cushion.

--K9Leader

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Yeah, I assume "knees in the seat" is what happened to mine... I haven't messed with it any more since my original message. It's been too cold and since I rarely have a passenger and the driver's side works fine, I'm not that motivated. Thanks for all the replies though, whenever I get back to it, I'm gonna compile everything that's been said here and I should be able to figure something out. If nothing else, 1stsubaruparts has the lower element for Legacys for just $75 now. The ones for Foresters are $226. :eek:

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Gentlemen

 

I was looking at a 2001 VDC today and when I checked the seat heaters the performance was either wimpy or nonexistent. As the day was not cold it was difficult to tell if the seats were heating. My question is do the Subie heated seats put out much heat when working? My Chrysler will cook eggs in 5 minutes. If they do not work any better than what I experienced today they are off the list. There is nothing between me and Canada except Lake Erie.

 

Thanks

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