Heated seat diagnosis

[WickedGoat]

Ok, I finally got around to trying to figure out the heated seat issue on my Yukon. My wife was complaining that the driver side bottom was not working and that recently it began to shut off within 5 mins of turning them on. So I do some homework and come up with the following...

The passenger side works fine, both back and bottom, independent of the driver seat. The driver side bottom did not heat up but the back does. The system either shut down after a couple of minutes or immediately after turning it on. Since I found 3 of the 4 warmers to be working, I took a leap of faith and ordered the driver side bottom warmer.

I got the thing and went out to the truck and unplugged the green connector for the bottom and plugged in the new warmer. The new warmer works but the system still shut down. Needless to say, I am stumped. I know the power door lock switch needs to be replaced because the lock switch itself on that side does not work. I haven't replaced it because it is expensive. I have read that this could contribute to the heated seats not working but I am not sure how that is possible.

Anyone have any ideas or suggestions on what to do? I replaced the leather on the driver seat and didn't notice anything with seat warmer. Wife said the seat warmer didn't work prior to me replacing the leather.

 

[SnowDrifter]

If memory serves, these trucks have some oddities where the bottom and back warmers are codependent.

Disconnect both and check the resistance with a multi meter

 

[WickedGoat]

Thank you... will try that this weekend.

 

[SnowDrifter]

Just remembered this one:

Do you have adjustable pedals? IIRC there's a dependency on those too

 

[WickedGoat]

Just remembered this one:

Do you have adjustable pedals? IIRC there's a dependency on those too

Yes it does have adj. pedals. They do work though.

 

[SnowDrifter]

Easy check is unplug the sensor and try the heated seat

 

[WickedGoat]

Easy check is unplug the sensor and try the heated seat

Ok, I will give that a shot. I haven't had a chance to mess with it yet other than just unplugging the factory warmer and plugging the replacement one in. It will probably be 2 weeks before I get to it but I will update this thread when I figure it out. Thank you for the ideas thus far.

 

[CountryBoy19]

The heated seats are all controlled by the driver's seat module. The module is "smart" in that in order to prevent fires/burns from shorted heaters it has temperature sensors and it measures the power input to each heater. If it senses something wrong, it shuts down. Power is fed to the bottom through the back. Therefore a faulty back (even if the back heater is working) can causing problems with the bottom. I found a helpful website that sells replacement seat heaters that said it's nearly impossible to diagnose which heater is the actual faulty one so they always sell/ship both and you plug 1 in at a time to see which one fixes the problem, then send the other back for a full refund. My passenger bottom wasn't working. I was trying to diagnose it; I turned the system on without the bottom connected and it immediately shut back down. The good thing is that because the module is "smart" it sets codes for the faults. The code it set when I turned it on without the passenger bottom connected was specific; "passenger heated seat circuit failure, bottom" or something like that.

I've also seen reference to the wiring for the bottom being vulnerable to chaffing so it's possible yours is chaffed and grounding/shorting out.

Do you have or know anybody that has a Tech2 that can check the codes stored in the driver seat module?

 

[WickedGoat]

I don't know anyone with a Tech 2... it would have been my first step in diagnosis if I did. Interesting info on the driver seat module. I believe our module is faulty or needs to be reprogrammed because the power seat slides forward when you push the switch for backwards and vice versa. The memory seat functions work when they want to. I read about the module reprogram by the dealer but that is hit or miss for the fix. I wonder if the heated seat issue is related to that?

The theory of the back controlling the bottom kinda makes sense. I plugged in the replacement warmer and it worked but the system still shut down. I looked at the website you are referring to and his deal sounds great but he wants over $15 to ship and then I guess you have to pay return shipping on the one you don't use.

I guess at this point I can do some testing with all of the suggestions posted here and make a decision. If I have to buy a back warmer then so be it. I can easily check the wiring since I will have the seat apart anyway.

 

[CountryBoy19]

I don't know anyone with a Tech 2... it would have been my first step in diagnosis if I did. Interesting info on the driver seat module. I believe our module is faulty or needs to be reprogrammed because the power seat slides forward when you push the switch for backwards and vice versa. The memory seat functions work when they want to. I read about the module reprogram by the dealer but that is hit or miss for the fix. I wonder if the heated seat issue is related to that?

FWIW, you can buy a Tech2 for less than the dealer will charge you to reprogram a module; I got mine with Candi module and TIS2000 (module programming software) for $300. You'll have to have an older laptop (Window XP I believe) to pull up the software to program modules.

As far as the seat sliding the wrong way, have you checked to see if that switch flips around? I wonder if maybe somebody didn't replace a switch at one point and get it in backwards and say "Screw it, I'm not tearing it all apart again".

If I have to buy a back warmer then so be it. I can easily check the wiring since I will have the seat apart anyway.

I would check the wiring out first... I would hate to invest in new warmers to find out it was a chaffed wiring harness.

 

[WickedGoat]

FWIW, you can buy a Tech2 for less than the dealer will charge you to reprogram a module; I got mine with Candi module and TIS2000 (module programming software) for $300. You'll have to have an older laptop (Window XP I believe) to pull up the software to program modules.

As far as the seat sliding the wrong way, have you checked to see if that switch flips around? I wonder if maybe somebody didn't replace a switch at one point and get it in backwards and say "Screw it, I'm not tearing it all apart again".



I would check the wiring out first... I would hate to invest in new warmers to find out it was a chaffed wiring harness.

I just trashed our XP laptop a month ago...

We have owned the truck since 2008. We bought it during the economic meltdown since the GMC dealer was practically giving trucks away. The seat switch and memory functions all worked as they should. It just started malfunctioning one day and we just lived with it. So none of those switches or any electronics have been replaced unless I did it. The truck has only seen a repair shop for the instrument cluster replacement (dealer extended warranty), vehicle inspections (I don't have an inspection license) and once for a dealer oil change (I wasn't available to do it and told my wife to go to the dealer). Oh, and tire replacement a year ago. Otherwise, all maintenance and repairs within my scope of knowledge have been done by me.

I have seen the cheap Tech 2 setups and have been tempted to buy since I am primarily a GM guy. I will get this figured out eventually, just don't have time right now... Chiefs game this weekend and my daughter has a swim meet all next weekend. My wife will just have to wait... she knows the alternative... spending unnecessary money at a shop... money that could be put towards something else, like beer and BBQ at the Chiefs game at Arrowhead!

 

[mountie]

I want to delete the heated seat switches.... My fingers touch the heated seat switch while adjusting windows. ( stupid location so near window switch)..... I wonder if I can remove a fuse for the heat switch??

 

[cmc76]

The heated seat element going out is pretty common. Drivers because it's uaed the most .Bottom, well because it gets the most compression.
Mine was doing the same .Swapped out the foam. Element and seat cover. No issues since.
I used the seat shop. But I know there are alternatives available

 

[M1Gunner]

My heated seats used to randomly come on and off on their one. Sometimes they would do this repeatedly and very rapidly. The indicator on the door would light up from 1-2-3 then off super fast with specific rhythm/pattern which obviously meant the relay would click along with it too sporadically.
Then one day my seat cuahion spring broke and I pulled one from a junkyard and then seat cushion was also still in really good cushion so I grabbed that too which included a heater.

When I fixed the springs I replaced the cushion and heater. Problem never happened again after that.

 

[CountryBoy19]

I just trashed our XP laptop a month ago...

We have owned the truck since 2008. We bought it during the economic meltdown since the GMC dealer was practically giving trucks away. The seat switch and memory functions all worked as they should. It just started malfunctioning one day and we just lived with it. So none of those switches or any electronics have been replaced unless I did it. The truck has only seen a repair shop for the instrument cluster replacement (dealer extended warranty), vehicle inspections (I don't have an inspection license) and once for a dealer oil change (I wasn't available to do it and told my wife to go to the dealer). Oh, and tire replacement a year ago. Otherwise, all maintenance and repairs within my scope of knowledge have been done by me.

I have seen the cheap Tech 2 setups and have been tempted to buy since I am primarily a GM guy. I will get this figured out eventually, just don't have time right now... Chiefs game this weekend and my daughter has a swim meet all next weekend. My wife will just have to wait... she knows the alternative... spending unnecessary money at a shop... money that could be put towards something else, like beer and BBQ at the Chiefs game at Arrowhead!

Sounds like a Tech 2 is in your future!!!! I haven't regretted it one bit...

 

[corvette744]

Im willing to bet its just one of the heating elements,you need to check the ohms on the wires.So raise your seat as hi as it will go,get an ohm meter and probe the connector- for the lower and upper at the connector.I would have someone sitting in the seat moving around-i had to do that when i found mine.Anything over 5 or 5.5 ohms its junk and needs replacing.Replacing the bottoms is easy the tops a little harder-and tops are more money.I cant stress the importance of pushing the seat or when someone is sitting in it to move around when testing-sometimes it wont show bad unless the burnt wires are touching.Thats how i fixed mine.

 

[TJ Baker]

I'll be looking forward to the OPs solution as mine is similar, including the reversed power seat control (press forward and it moves backward and vice versa).

 

[sumo]

This tool makes diag on heated seat easy to tell if it’s working or not. You can pick up a Milwaukee version from home depo. A lot of the times a section of the heating element shorts out rips or breaks. Once that happens current can’t flow and it won’t get warm.

 

[WickedGoat]

Ok, so I finally got around to playing with this today. I replaced the lower element on the drivers side... no dice. System still shuts down. I disconnected the power adj brake pedal and no change. Tomorrow I will test the wire and connector with the meter, with someone in the seat moving back and forth and see what the Ohms reading is. All of the wiring I could see was fine... no chafing or burning anywhere. I will keep at this and hopefully figure this out.

 

[corvette744]

Test all elements before replacing anything.Should be very obvious on the meter which one is bad.Mine was the upper drivers seat.