Heated seat diagnosis

Discussion in 'Interior' started by WickedGoat, Oct 7, 2018.

  1. WickedGoat

    WickedGoat Member

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    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.
     
  2. SnowDrifter

    SnowDrifter Full Access Member

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    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
     
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  3. WickedGoat

    WickedGoat Member

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    Thank you... will try that this weekend.
     
  4. SnowDrifter

    SnowDrifter Full Access Member

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    Just remembered this one:

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

    WickedGoat Member

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

    SnowDrifter Full Access Member

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    Easy check is unplug the sensor and try the heated seat
     
  7. WickedGoat

    WickedGoat Member

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    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.
     
  8. CountryBoy19

    CountryBoy19 Full Access Member

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    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?
     
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  9. WickedGoat

    WickedGoat Member

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    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.
     
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  10. CountryBoy19

    CountryBoy19 Full Access Member

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    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.
     
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