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New "How to fix the seat heater" thread.

109K views 74 replies 50 participants last post by  ChevyGal2005 
#1 ·
Hey everyone....I needed to re-do this thread because my picture host went belly-up. Anyway, here goes:

Hey everyone! I had seen multiple posts about this problem while I was searching for a "How to" on changing out the p.o.s. seat heater coil that GM graced us with. Well it seems that nobody had replaced one themselves, or at least nobody was giving any hints on how to do it, so I decided to try my hand at writing my very first "How to" thread. So....here goes:

I ordered the Dorman replacement unit from RockAuto.com (Part number 641107). The unit was $67.00 + delivery charges. It took about 4 days to get it. (You can also order the OEM unit from GMPartsDirect.com, part # 88949407, for about $80.) Here is what comes in the Dorman package:


It also includes this pair of pliers and a bunch of clips:


Now to get to it:

1st adjust the seat so that it centers the bottom cushion over the seat rails. Lean the back of the seat slightly backwards for easier removal of the bottom cushion.

Next you need to unplug your battery so you don't fry anything important. You will need an 8mm wrench or socket to pull the negative battery cable off.

Now it's time to remove the whole seat. Start by removing these caps:


2 of mine had broken clips that hold them on. (We bought this TB used. It was 2 years old.) The unbroken one required a small screwdriver to pry the clip open so the cap could be removed. Be careful not to break the clips. There are 3 caps in total.

Under each cap there is a nut:


Remove these 3 nuts with an 18mm socket. They do require a decent tug to get them broke loose. The fourth "corner" of the seat is held down with a bolt, not a nut. It is the same size as the 3 nuts.

After removal of the nuts and bolt you will need to lift the seat off of the studs the nuts were on. I lifted and slid the seat rearward about 3 inches. Then I tilted the whole seat backwards so I could disconnect the wires underneath. There was only one connection. It is purple and black and it
looks like this:


To disconnect this plug you need to squeeze the black tabs together at the bottom and pull on the purple lever. Once this is done the plug easily comes apart. (There is a diagram on the back of the plug showing how to do it if you need help.) Mine also has a little yellow plug, as seen in the picture, that has a jumper in it. I don't know what it is for, but it was never plugged into anything.

Now, you will need to lift the whole seat out of the vehicle. (I would say the seat assembly weighs about 80 lbs. Get help to lift it out if needed. Don't hurt your back.) I placed an old, clean bed sheet on the floor in the garage next to the TB and placed the seat on that to keep it clean. Set it down so that you have access to the underneath side of the seat.


With the seat out of the TB I decided to remove the bottom cushion from the rest of the seat. To do this you will need a 13mm deep socket or 13mm wrench to remove 4 nuts, 1 from each corner. They look like this:


Once all 4 of these nuts are removed, you can lift the bottom cushion off of the seat frame. There are a couple of plugs that need to come apart to remove the bottom cushion. The hardest one is plugged into the black box under the seat cushion. I had to stick a small screwdriver down the hole and pry on the locking mechanism to pull it out. Other than that it was a piece of cake.

Now, a word of caution: There are some sharp parts on the seat frame that can cut you open pretty good if you are not careful. I was not careful.


After a little bit of TLC from my wife, and a band-aid, I was ready to get back to work.


This picture is of the connector that goes to the heating element. Disconnect it.



Now we need to remove the leather cover and foam pad from the springs/frame. Start by removing these two clips. (I used a small screwdriver to stick inside the clip and pry it off of the metal frame.)




Now go to the back of the seat cushion and remove the clip that holds the leather to the frame. It looks like this:



Here is a picture of it un-clipped:



This picture shows the velcro that holds the heating element cord out of the way. Pull it open and pull the cord out of the flap.



Next, you need to remove the panel that holds the seat controls. It requires a long phillips screwdriver to get to the 3 screws.



With the controls removed it is time to pull off the clip that is holding the front of the leather to the seat frame. It is very similar to the back clip and it comes off pretty easily. With all of the clips removed the foam cushion and the leather cover will come off of the steel frame. I took the cushion into the house to remove and replace the heating element. When I started to pull the leather off of the foam I found out why my heating element quit working. It had burned one of the wires completely in half, and burned the foam cushion and the underside of the leather seat cover. Check out the picture:



Now comes the hardest part of this whole deal. There are a bunch of steel clips that hold the leather to the foam cushion. There are three at the seam toward the front of the seat that goes from left to right that must be cut and removed in order to swap the heating element. They look like this:



The 3 clips need to be cut with ***** and completely removed from the cushion and the leather tab. I used needle nose pliers to fish the clip out after I cut it. Tip: Don't just yank the clip out of the foam. It goes around a wooden dowel that is embedded in the foam. Do not break the dowel or pull it out of the foam. You will need to replace these clips with the ones that came with the heating element. Leave the other clips in the seat. You do not need to remove them, unless you want to. They are a huge pain to replace, at least they were for me.

The next step is to remove the heating element. It is stuck to the foam cushion with double sided tape on the sides and across the front. You need to pull up on the corner of the heating element and carefully remove the element from the foam. Be careful not to pull big chunks of foam off. Shimmy your hands down under the sides until it is completely un-stuck from the foam, then simply pull the element out. Mine looked like this when I got it out:



And this is what the inside of the leather cover looked like:



Now compare the original heating element to the new one. In this case they look exactly the same.


To install the heating element I slid it underneath the leather cover and matched up the edges with where the original one was. (You will be able to see where the old tape was stuck.) I started with the front edge and peeled the backing paper off of the tape and stuck it down. (Make sure the cord is coming out of the same side of the seat as the original one was!!) After sticking the front down you need to replace the metal clips that were cut. This was the hardest part for me. I stuck the clip into the foam and around the wooden dowel. Then I stuck one side through the leather tab and then I tried to squeeze the ends together with the pliers they supplied. Apparently I am not an upholstery genius because I couldn't get the pliers to crimp the clips at all. I resorted to using the needle nose pliers for this, too. It didn't turn out as nice as the stock clips, but it worked. Try to point the ends of the clips downwards so you don't get poked when you sit on the seat.

After the clips were replaced I stuck my hand under the element and peeled the backing paper off of the tape that runs down both sides of the heating element. (One side at a time.) Stick them down and then pull the leather over the foam cushion so it looks like this:
 
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#2 ·
Now you should be ready for re-assembly of the bottom seat cushion to the steel frame. Start by turning the cushion upside down and placing the steel frame on it. I matched up the springs to the depressions they left in the foam
to line everything up right. Then I started with the front clip and attached the leather cover to the steel frame. Then I did the side clips, then the back clip. When you are finished it should look like this:



Next, make sure you route the cord from the heating element through the same flap that is held shut with the velcro. Remember to plug the heating element cord into the connector, too!! Put the three screws back into the control panel and attach it to the side of the seat.

Now you are ready to re-assemble the bottom seat to the rest of the frame. Place the bottom assembly close to the seat frame and plug in all of the connectors that you disconnected before. Make sure you get them all--I almost forgot the seatbelt connector. After all the connectors are in place slide the four studs on the bottom of the seat cushion assembly through the four holes in the seat frame and tighten the nuts that you removed previously with the 13mm socket. (I don't know the torque #'s. I just made them tight.)

Now all that's left to do is to pick the seat up and place it in the vehicle. Remember, it is kind of heavy and you may need some help. I placed it 3 inches behind the studs, leaned it back and plugged the connector in. (Remember to lock it into place with the purple lever.) Now, lift the seat over the studs and replace the 3 nuts and the one bolt with the 18mm socket. (Again, I do not know the torque #'s for these fasteners. I just tightened them up pretty good.) Don't forget to put the caps back over the nuts. Hook the battery up with the 8mm wrench and go for a test drive. Now you have a seat heater that works!!:woot:

This whole process took about 4 hours, including first-aid and lunch. (I believe that this write up took longer than the swap.:bonk:) I'll try to answer any questions that you might have........
 
#3 ·
Great writeup. This is what I've been looking for.:thumbsup:One question. How did you determine that it was actually the heating element? I have the same problem where only the bottom heater does not work. The "back only" button does not light up, regardless if pressed not. Is this the same case as yours? :confused:
 
#4 ·
I am not sure if the "Back Only" light would come on or not? This is my wife's vehicle and I only drive it occasionally. One time when I did drive it my leg was burning in one spot then shortly thereafter she told me the lower part of the seat heater was not working. I looked on this forum and found that several others had the same experience, a really hot spot on their leg. One of those people said that they had taken theirs in to get replaced twice, but nobody else had fixed theirs. So, I decided to try it out and this thread is the result of my attempt. Good luck! (If you want to tear your seat apart before ordering the replacement element "just in case", it only takes a couple of hours to do so. Then you can just pull back the leather seat cover and check to see if it's burned. Heck...You could probably check it by just pulling the seat out and prying the clips off that hold the leather seat cover on. Less than an hour to do that.)
 
#5 ·
Thanks for the tip. That's what I might end up doing before buying a brand new heating element. You don't happen to know what caused the burned out wire do you? Is the new heating element superior in design to the old one in any way? I know you mentioned some folks having to have it replaced several times. It would be a bummer to go through all that and have it fail next winter.:hissy:
 
#6 ·
Actually, the new element looks almost exactly like the original. As for the cause, the unit dips down to go through a little valley where those steel clips attach the leather cover to the foam and I think the resulting "u" shape gets hot and burns through. I told my wife to run it on the middle heat setting to see if we can make it last longer.
 
#7 ·
Thanks for this write up.. just what I was looking for.. Glad (maybe not glad, but at least less upset) to see that I'm not the only one experiencing this exact issue.

That said, I'm concerned about that failure.. I mean what kept if from just lighting the whole car on fire? I guess it's not such a big deal because it won't run unless you're in the car. With my remote start, if the on/off state were to be kept between starts I'd be more concerned (i.e if it was on when I turned off the car and remained on when I remote start it).. but thankfully it doesn't do that.

Oh, and those clips I believe are what they call "Hog Rings" and they are the toughest part of upholstery. Thanks again. I think I'll be doing this in the next month or so, as soon as we get a nice weekend.
 
#9 ·
Wow..thanks for the incredible post. Got mine done in about an hour, and that included talking to the paperboy.

Couple of things I should mention:

o I found to help diagnose the problem, you can unhook the wire to the seat heater and test it with a voltmeter. If you get voltage out, you know it's probably the heater pad. I went to the trouble of removing the seat and getting an ohmmeter on the heater pad. It was open, so I knew that's what the trouble was.

o I couldn't get the connector off of the control module on the bottom of the seat. Ended up pulling the other connectors off, unscrewing the module and "leaving it behind"

o When I removed the seat cushion, It spun around and snapped off the wire for the seat belt sensor. No biggy really..I didn't bother to hook it back up and with the wires severed, it just thinks the seat belt is always plugged in.

o I found I only had to remove 2 of the hog rings...was able to slip the heater in without taking the third one out. I reused the same hog rings.
 
#10 ·
Failure mode

Oh..as for the failure of the seat heater. In my opinion what happens is the wire makes a bend when it goes through the "hog ring" section. The constant getting in/getting out of the seat flexes that wire. Over time, strands of copper break, and at some point, too much current is going through too few wires and they burn out.

I don't think it has anything to do with what heat level you run it on..but more, how much flexing the seat takes.
 
#14 ·
Super Write up

I had the same problem, no seat heater but back heater was working. After reading this thread I ordered a new seat heater, now cost about $80.00 from RockAuto.com. Your directions were perfect. I had my set out repaired and reinstalled in less than 2 hours. The failure again was in the same spot. My guess is that the heater wire doubles up at that location and causes it to overheat and burn up. Kind of scary when you think about it. The seat had caught fire in a very small, tight place and didn't ignite the entire seat and then the whole car. I cut away some of the plastic rod so the wire has less pressure on it. Works great and was very easy to replace. Thanks again for the great writeup.
 
#15 ·
I had the same problem, no seat heater but back heater was working. After reading this thread I ordered a new seat heater, now cost about $80.00 from RockAuto.com. Your directions were perfect. I had my set out repaired and reinstalled in less than 2 hours. The failure again was in the same spot. My guess is that the heater wire doubles up at that location and causes it to overheat and burn up. Kind of scary when you think about it. The seat had caught fire in a very small, tight place and didn't ignite the entire seat and then the whole car. I cut away some of the plastic rod so the wire has less pressure on it. Works great and was very easy to replace. Thanks again for the great writeup.
You are welcome! I am glad this "How To" thread has been of use to so many people! (I just hope nobody else cut their finger like I did....):thumbsup:
 
#16 ·
How to Fix the Seat Heater

GOFASTER, GOBLUE and everyone else - this is the best (and about the only) thread on this topic I've seen.

I am 99.9% certain that this is my problem except ......

My symptoms aren't quite the same as what you guys describe. None of my seat heaters work (seat or back, driver or passenger). I can't believe that all four elements would have fried at exactly the same time.

When one of the elements burn out do all of them stop working? When we try to turn on any of the heaters, the light on the door switch / button turns on while we're pressing on the button, but turns off as soon as we let go. That seems to tell me that the door switches, fuses, etc. are all working but that there is some common point in the system that is broken that prevents all of the elements from working - which might mean that none of my elements are burned out?

Is it possible that if the "first" element in the system is burned out that the system works as a series and therefore none of the elements work or is it more likely that I've got a different problem?

I've tested fuses CB#8 and fuse#19 and both of them are fine.
 
#19 ·
Sounds like my issue

Couple days ago i noticed the seat part wasnt getting warm, just the back. i am also glad i am not the only one with this problem. Glad i found this write up looks like i'll be looking into this soon. Just joined this forum couple weeks ago and glad i did!
 
#21 ·
GOFASTER .. awesome thread man. My girlfriends heated seat just stopped working (she constantly uses it on high). I'm going to try and test the voltage this weekend first but just knowing that this thread is here has kept me from shying away from it and putting it off. This is definately sticky worthy.

Thanks!:thumbsup: :thx
 
#22 ·
thanks for the awesome writeup. it helped me out huge today. I did notice a few differences b/w my 05 envoy slt and your model, but all in all pretty much the same.

the hog rings are actually not difficult to remove (just cut with a wire cutter and pull it out) and even easier to install once you understand how the tool is supposed to work. I had my blackberry in one hand and the hog ring and the installer tool in the other, so the video isnt the best...but you should get a good idea of how it's supposed to work by clicking this link:
http://www.youtube.com/watch?v=AAiE2b-RVRU

hopefully this isnt against board rules to post youtube vids here...
 
#24 · (Edited)
Great writeup and excellent pictures.

I did this 2 weekends ago and it went just like the instructions....
Until I got in, turned on the heat and it didn't seem to work at all (buttons seemed to be sluggish at operating the lights) It finally started heating, but only the bottom at full blast no matter what the control showed, previously only the backrest was working.

I figured I pinched a wire or something. So I got the tools back out to remove the seat.

I remembered that the base of the seat was held on with (4) nuts on studs to the seat frame so I raised the seat up with the controls and was able to remove the nuts without removing the whole seat :woot:!! I did remove the side controls trim. At this point if I was replacing the element I could have disconnected the wiring and worked on it.

With the seat base in a partially lifted position, I was looking for the cause of my issue and noticed that the connector (8 pin??) on the console side of the seat that connected the base to the backrest was not plugged in, I had forgot this connector when assembling. So I fiddled with it (lifting the seat cushion with the rest of the wires connected is tricky) and finally got it plugged back in.

Set the seat base back on the frame and put the nuts back on and Done.

Now I'm thinking..:duh: why didn't I do this at first and not have to take the whole seat out !!

This method (or shortcut) may save a lot of you a bunch of time and make the job manageable for the ones who are shying away.

Also, I was able to "open" the hogrings (clips) with 2 sets of needle nose pliers and just reuse them putting it back together using the two needle nose again. I made sure where the two ends were was facing down so no pokes through the leather could occur.

Hope this works for everyone.
 
#25 · (Edited)
Yellow plug in seat

Go Faster mentioned a yellow plug that had only a jumper in it.
Yellow plugs mean airbag system. It seems to be an option on some models, as Roadie said on another thread.
http://forums.trailvoy.com/showthread.php?t=83680

My 07 envoy is a base model but it has that yellow plug connected and the cable runs up to the back, so I assume I have an airbag in the seat back edge.
Funny thing is the vin description does not mention this and neither does the handbook; it only mentions optional roof mounted curtain airbags.
 
#26 ·
A bit :eek:fftopic:

All yellow plugs mean Airbag components. On my 04 there is an airbag in the side of each front seat back, with impact sensors in each front door. In 05 and later years a Side Curtain airbag that came down from the headliner was used.

A jumper is built into the airbag side of every Airbag connector to help prevent static electricity from setting off an airbag. The "shorting bar" is disconnected when the connector is properly mated to a matching connector.

On both systems there are seat position sensors built into the front seats to report the seat position (to indicate if Low or Normal deployment speed is needed) and the passenger seat has a sensor to report if the seat is occupied. This means front seats for all years should have some sort of airbag system connector either for just the sensor(s) or sensor(s) and airbag.
 
#27 ·
THANK YOU for posting the photos and information.

I spent something like an hour and a half replacing the driver's seat heater in my '03 Trailblazer LTZ. Hog rings are definitely the worst part for me, the included tool could go right into the scrapmetal bin. I used needle-nose pliers and lots of harsh language. 7 hog rings removed to access the heater; 7 original hog rings re-installed. Everything else was EASY. I never pulled the seat out of the vehicle--just unbolted it from the floor, tipped it back and unbolted the cushion from underneath.

The Dorman replacement unit is unfortunately made in Communist China; but even so it went in and fit reasonably well. Summit sells it for $66 + shipping as of 4 March 2011; I paid $92 at NAPA (BK 7454003) with sales tax because I needed it "overnight".

http://www.summitracing.com/parts/RNB-641-107/

http://www.napaonline.com/Search/Detail.aspx?R=BK_7454003_0258224887
 
#72 · (Edited)
The Dorman replacement unit is unfortunately made in Communist China
The original passenger seat cushion heater failed last summer, (It still "works", but produces a hateful hot-spot mid-thigh) The driver's side--replaced in March 2011 with the Dorman heater--also failed completely again.

I get to do the passenger side in the next week or so. I did the driver's seat this afternoon. The original photos in this thread from post #1 have expired due to Damned Photobucket, so here's my photos. Vehicle is a 2003 Trailblazer LTZ, 4.2L, not an extended version.

Best price I found for a Dorman 641-107 is Amazon. NAPA wants $188 for the thing, which is insane--although the "Limited Lifetime" warranty helps. https://www.napaonline.com/en/p/NDP7454003
Summit wants $119, which is bad enough. https://www.summitracing.com/parts/RNB-641-107/
Amazon is asking $75. https://www.amazon.com/gp/product/B001KQA9ZE/ref=ox_sc_act_title_1?smid=ATVPDKIKX0DER&psc=1

First off, I disconnected the battery to prevent any possible air-bag explosions, and then I tested the new seat heater with an ohmmeter. It reads 3.5--3.6 ohms at the green connector. The broken seat heater will read "Open" or "OL", Out-of-Limit (depending on your meter) for that range on the ohmmeter because the internal heating element will be burnt-through at the "pleat" where the upholstery is secured by the hog-rings. There were some times I could get an ohmmeter reading of the old, burnt heater, but they were in the 10-ohm range, not three-and-a-half ohms like the new one.


The side-panel that holds the seat adjustment switches is also broken on my Trailblazer, and will be replaced as part of this operation. That's why my seat-adjustment switches are just dangling from the wiring in some of my photos.

The seat cushion can be EASILY unbolted from the rest of the seat assembly. Two 13mm nuts near the front edge of the seat, two 13mm nuts accessed from the rear, near the rear edge of the seat. Disconnect FOUR electrical connectors, pull the seat out (with the seat-panel assembly that includes the seat adjustment switches.) Other model years may have additional wiring connectors--I don't know.

The rest of the seat assembly stays in the vehicle. DON'T unbolt it from the floor. Raise the seat using the adjustment switches, for access to the four nuts, and the electrical connectors. I put it in the middle of the fore-aft travel, but I don't think that's critical. This is a really good time to vacuum under and around the seat. I blew fuzz and crap out of there using compressed air. Found one dime and one nickel. Believe me, this job is worth more than fifteen cents.


I lifted the rear of the seat bottom from the seat assembly, and started to disconnect the electrical connectors. First electrical connector is a thin two-wire deal attached to the seat belt


Right next to it is a bigger multi-wire connector.


Those two connectors plug to the mating connectors near each other. These are the matching connectors on the seat cushion.


Only one plug is disconnected from the electronics "box" under the seat cushion. Easy to get at either from underneath, or with the seat cushion lifted up for access.


And the wire/connector that stays with the seat assembly


The final connector on the seat cushion, easy to get at from underneath.


...And it's mate that stays with the seat assembly, at the front edge of the seat assembly.


With the electrical connectors undone, the cushion can be fully removed. Somewhere in here you'll need to remove the three screws that hold the seat-adjustment switch panel--but mine's already broken off. Flip the cushion over, there are 6 upholstery clips and a bit of Velcro to undo. First two clips on the cushion sides:


Third clip, along the outer side by the seat adjuster switches:


Fourth, along the inner side:


Fifth, at the cushion front (or rear, I forget.)


And a spot of Velcro


Sixth, and last because the others need to be released and the foam flipped-up to get at this one. Seat cushion rear (or front, I forget.)


This gets us to those hateful hog-rings, and where the harsh language commences. Remove the upholstery from the hog-rings in six places (circled in red). Work from left to right as pictured, lower edge, then undo the two higher up. The seat heater is visible. Note the burned section. The seat heater is held to the foam with sticky-tape, and it'll peel some foam up as it's pulled loose. At this point, you'll disconnect the green connector to get the old heater separated from the rest of the seat-cushion wiring. Note how the seat-heater wire and connector is secured to the seat cushion frame. (not pictured)


The old seat heater removed. Obvious scorched area--common as dirt. They all seem to fail in the same place.


At this point, shove the new heater in place where the old one was, re-connect the hog rings in reverse order (replace if needed--I re-used all but one.) Stretch the upholstery back over the foam, tucking the foam nicely and neatly to remove wrinkles from the upholstery. Replace all the plastic upholstery clips onto the cushion frame, starting with the last one and going "backwards". Push the green connector together and secure it to the cushion frame.

Drop the seat cushion back onto the seat assembly, leaving space to re-connect all the wiring. With the wiring handled, the studs on the cushion frame drop through the holes in the seat assembly. You tighten four nuts...and test the seat heater.

Mine is nice 'n' toasty, with no hateful "hot-spot" mid-thigh. Success. Drink much beer in celebration.
 
#29 · (Edited)
The picture only shows the heater for the bottom of the seat, scale may be a little hard to see. The separation of the small and large heating area is where there is a seam in the seat and the heater has to go under it. The smaller part of heater is near the front of the seat near your knees.

The weakness in the heater element (why we all need to replace it) is where this seam is and I have not heard of a seat back heater going out. The replacement Dorman element supposedly has a larger loop area to go deeper into the foam where the seam is and prevent a re-occurrence of the failure.
 
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