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Seat Heater repair

tnathan

Full Member
Joined
Feb 27, 2005
Messages
11
Hello all,

I have a 2002 chevy avalanche.

The passenger side seat heater has stopped working but the driver side works fine.  The controller for the passenger side works fine.  It comes on and stays on until I turn it off, but no heat.  So unlike others who described a short that causes the controller to switch off, mine stays on. 

I thought that the problem would be the standard broken wire in the pad, so I bought a new one from GM and replaced it.  Unfortunately, the seat heater still doesn't work. 

I then thought I should check the fuses.  However, the only thing I found was a seat heater relay in the block below the steering column.  I think I found it but rather than finding a fuse or a relay that I could replace, I found what looked like an electrical connector.  Am I missing something?  Is there a passenger side relay or fuse that I have missed.  Based on my symptoms any suggestions on anything else I can try?  I took pictures of the relay block but I can't figure out how to upload on here to show you what I was looking at.

I have run out of ideas.  Thanks in advance.

Tim
 
I suspect for some reason that your element has failed "Open Circuit"...  where as for most of us,  it is burned out but still conducts more than it should and shuts down the system... 

The hardest part is getting the covers off... the seat bottom is much easier than the top...    have you tried both buttons?  turning on "Just the heated back" vs "both"...
if neither work, start with the back element...  check the plastic connector before you remove the cover...  this may require removal of the seat (which is not really that hard)    Read up on it first, cause you need to pull the air bag fuse...
 
Thanks that is what I am thinking now too.

On the 2002 you only have h/l you can't pick seat back or bottom.

I guessed it was the bottom seat pad that failed given it gets more weight than the seat back and assuming the pads are wired In series.  But, replacing it didn't do the trick. 

I saw a few threads about fuses hoping that i missed something but none of the threads actually point to a seat heater fuse.  Given that everything else in the car seems to work, I guess that is going to go nowhere.

So, as you suggest it may be the seat back pad, but I hate removing upholstery.  Or, even worse I have an open circuit somewhere between the battery and the resistor pad.  I looked at the wires beneath the seat and didn't see anything frayed,vconnectors secure, etc.

Thanks for the thoughts

Just wanted to,check to see if I am missing something easy.

By the way, I don't know where you all get these pads but I had to get mine shipped from mass.  My dealer told me they have been discontinued and there were only two left in the country.  I couldn't find any after market either for the 2002.
 
Sorry for replying to my own message I searched through previous posts and didn't find much.  I hate removing the upholstery.  Are there any tips or tricks to make this easier.  It always ends up being some experience like trying to fit into my leather jacket from highschool.  I could have swore everything fit in there when I took it off! :laugh:
 
You shouldn't have to remove the upholstery to replace the heat element for the back. You should be able to just release the plastic j-strips at the bottom of the seat trim, then run your hand up inside the front to release the velcro that attaches the trim to the foam. That should give you access to the heater pad, which is adhered to the foam with an adhesive strip. But you already know that since you've replaced the cushion pad already. You may have to play around with the seat recliner to get access to release the two plastic j-strips; it's usually easier said than done.
 
I was able to roll/bunch the back seat cover up just enough to get that element out (the armrest will stop you dead from getting further), and put a new one in... however...  if you suspect "open circuit" then all you need to do is disconnect the green plastic connector to the seat back element and measure resistance...  if it is does not measure/ is infinite, then you KNOW....    I am surprised if someone was able to do this blind without at least rolling/bunching it up 8 inches or so..

I bought one of mine on Ebay... Dorman makes replacements for these elements...  search "dorman seat heat element" on ebay...      i really doubt there will be a shortage for long, this is a common problem...
 
Thanks for the replies. 

I was hoping that there was a magic button for releasing those J hooks.  I will check the resistance in the seat back.  I am not sure if I want that to be the problem or not.  If it is, I have to wait for another part to come in, but I can check this off my list of projects.  On the other hand, if it isn't the rear pad then I have no idea where my open circuit could be.  And franky I suspect that the rear pad is fine.  I can't tell for sure, but I think the rear and bottom pads are run in parallel.  If so and the rear pad failed, I would have thought the bottom pad would have continued to work especially now that I replaced it with a factory new part. 

The connectors look fine.  After that I have no idea how to trace this any further. 

Maybe a connector under the seat?

Could the the switch in the door be bad even though it lights up? ("lights on but not actually sending current to the seat).  Arghh.

The only thing worse that spending $600 at the dealer is spending $200 yourself and then spending $600 at the dealer.
 
Thanks for the idea of checking the resistance.  I got 2.5 ohms so I am pretty sure that I don't have an issue in the seat back, which is great. Otherwise, I would have been torqued if I took it apart and all was well. 

So, right and left controls light up.  Seat pad replaced and seat back shows continuity.  So, anything else worth checking?  I still wonder if ther isn't a relay or fuse somewhere, but I don't see anything labeled other than the heated seat relay by the steering column but when I checked it looks like a wire connector.  Nothing there to replace as far as I can see. 

Thoughts?
 
read thru the other heating element post. Somewhere the is a check list to go thru something about if the pedal adjustment switch and or power seat are working correctly the heated seats don't work. I am in process of finding out why my drivers side heater shuts of in a few seconds and never heats up
2500
 
I'm not sure on the Avalanche, but there is usually a control module somewhere. Most of the time it is located under the seat and the heat elements plug into it. It could certainly have gone bad.
 
2.5 ohms doesn't mean that its good, but it doesn't mean its bad either...  just means its not open circuit...    even when mine were nice and toasty burned out, they ohm'd out the same as a brand new one...  I believe it was close to 2.5...        I did everything i could to check if bad before pulling the seat cover and I don't know if it is possible to tell without looking at the thing...  in 99.9% of cases when the seat heater turns on then immediately off, one of em is bad...    in your case where the light stays on and there is no heat,  I would try at this point try swapping parts...  does the passenger seat and drivers seat both have the problem?  if its only one, you could swap the door controls for a test maybe?

 
Another simple test you can do:  use wire/alligator clips/whatever to allow you to measure thee voltage drop across the element while turned on    it would be interesting to see if you are even getting power to the element
 
Whoever said easier said than done was right.  I've run out of time and daylight today but need some direction.  And I apologize if I don't use the correct technical words.  I have posted before and will say it again, I have little mechanical knowledge but a willingness to take apart and reassemble.  I can't find my original string/posts on this topic so I piggy back here. 

In short I had problems with the driver seat heater going out.    I will spare the cuss words related to getting the seat out, disconnected and de-upholstered enough to make the switch.  I DID find the short was in the back, not in the seat.  OF COURSE, I started my project in the seat.

I used the DORMAN products as recommended in this forum.  The instructions are identical for each pad regardless of specified use and I don't see an answer about my issue. 

I replaced BOTH the driver seat and back heater pads in my 2005 today.  The seat only had one wire harness and one connect.  Green to green.  Due to access, I was able to take the old heat pad out.  It looked like I was going to do a lot of damage to the foam by peeling off the original adhesive so all I cut the pad at the margins of the adhesive and left the remainder.  I used 3M spray adhesive to keep the new pad in place.

The back heater wire harness has the mate to the seat green connect but there is a longer part with a multi connect.  I did not know where this goes and could not seem to find the appropriate connector to replace.  The old seat pad just has the one wire?? WHAT DID I MISS.  There are a bunch of other wires coming from the seat but I presumed those were for the lumbar support and recline motors.

On top of that "dangling wire harness", due to the difficulty of stripping up the seat cover, I left the old pad in place and just worked the new pad onto the old pad.  I disconnected the old and put the new green to green.  Then I  reassembled the whole kit and caboodle. 

I started the engine.  Adjusted my seat.  When I tried the heater it immediately goes out - Driver and passenger sides.  Immediately.  At least before I started the project, my wife could sit in the passenger seat with warmth. 

So, it may be a few days or a week before I can get to this again.  What a pain.  But can someone suggest what to do now, and if possible can I get a reference to a link that shows all this stuff.  I have tried searching the forum, the web and YouTube but just not hitting the right places.

Did I do wrong by leaving the dead and disconnected old back heater in place?  :E: :E:

Thanks and Happy Thanksgiving.
 
I believe that is your problem the side back has a temperature signal in it.
 

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Please forgive my inexperience, it's been years since I had to read a schematic in school.  And unfamiliar with the product, that is way too much for me.  What does it mean and what is your suggestion for trouble shooting?

Thanks and thanks for putting up with a novice!!
 
No problem at all, sometimes it takes a while for me to respond if I'm not at home and posting from a smartphone.
 
The heater pad for the seat back has two connectors.

The smaller connector is where the seat bottom attaches to the circuit.

The larger plug has a matching socket toward the middle of the area under the seat.

Don't sweat adding any adhesive to the pad or even be concerned about using the sticky-backed tape that comes attached to the new pads.

When you get the pads in their location, the Velcro strips that mount the seat skin to the seat foam will keep everything in place.

I just ripped the old pads out and positioned the new pads in the correct place then pressed the Velcro fasteners into their location.

Those pads aren't going anywhere.

And the new ones ARE NOT DIRECTIONAL, so don't get hung up on which side of the pad the tape is on.

Just place the new one in your seat to match the orientation of the old pad.

The placement of the connecting wires is more important than worrying about where the tape is located on the pad.

Get that right and you are good to go.

I have done this a couple of times now and I find it is easier if I just go ahead and take the seat out of the truck to work on it.

Check out this page of videos at The Seat Shop to help troubleshoot the heater problem and how to skin the seats.
 
Thanks so much for the reply.  I guess I need some time to get to things again and it may be next week some time.  I need to find that extra connector.    I'll be back if I continue to blunder!
 
Thanks for all the help everyone.  I had time yesterday and got my seat out.  The multi-pin connector for the seat heater back was right there in plain sight.  I don't know why I didn't see it the first time.  I got the Dorman product connected, seat reinstalled and tried it out.  I got heat in my seat and the light stayed on!

I appreciate all the help, patience and direction. 
 
I had my driver seat cover repaired on my 2002.  I had the upholstery shop replace the burned out seat heater elements with a Gorman after market.  I want to use the GM wiring from my old elements but since they were removed, I can't even find where the old harness plugs in. Will the GM harness and relay work on the Gorman or do I have to use the new gorman harness and switch? Also, where is the old harness 3 wire plug located?
 
The Dorman replacement units have the very same connectors as the OEM units.

Plug and play.
 
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