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Discussion Starter #1 (Edited)
NOTE: Always disconnect the 12V battery for awhile before messing with seat connectors due to airbags in the seats...

One of my grips with the Bolt used to be due to the pathetic amount of "heat" the "heated seats" would create. The heated steering wheel is great and will get up to ~120F, which will add heat into the body. The OEM Bolt seats would not even get above body temp, so they don't really "add" warmth to the occupants. And the amount of heat was far less than any of my other vehicles with heated seats.

I gripped about it and posted infrared measurements in this old thread where the temp gun was showing a max of 95/96 F on the "high" setting: https://www.chevybolt.org/forum/226-interior/30687-heated-seats-seat-covers.html

The reason GM and others are going to lower temp heat levels has to do with lawsuits against auto makers where people have sued, and won, for damaging their skin from heated seats getting "too hot" and occupants not taking precautions to make sure they don't hurt themselves. The Nanny State wins again and we have to dumb things down for everyone else...

There are lots of online rants about GM's newer models having pathetic heat output from their "heated seats". This was confirmed by multiple calls to local chevy dealers who confirmed the lack of significant heat output on newer models, and I was told there was no way to calibrate the heat level with software intervention.

So, this weekend I did some Redneck Engineering and hacked/modified the seat heater control module to do my own calibration of the driver seat heat level. I am happy to report that this relatively simple modification (if you can cut and solder) will raise the seat heating output above body temp and actually warm the occupant in winter cold conditions. In fact on "High", it gets a little uncomfortably hot... you might not want to go with quite as large of a series resistor that I used, which was 2.2 kOhm.

The general theory of operation is there are thermistors with negative temperature coefficiets in the seat back and bottom that relay changing temp information to the seat heater control module. As the seat warms up, the thermistor value decreases and the sensing current increases. To make the seat get hotter, I cut into the circuit and added a fixed, non changing resistor inline with the thermistor. This shifts the entire temperature control behavior "up". The amount of the shift will depend on the resistor used.

I updated the photo link with some pics of the seat heater control module (its under the passenger seat), how I used an electrical heater blowing on the driver seat to isolate that seats thermistors (as the seat warmed up I can measure which resistance values were getting smaller), which leeds in the heater control module I cut, the 2.2k ohm resistors soldered in series across the cuts, and then pics of the new seat temps after returning from home this afternoon (the bottom cushion is a little hotter than shown when sitting on it, but the seat surface cools off rapidly with the door open and 20F outside temps and by the time I aimed the gun there it had decreased to that level).

Link to pics: https://photos.app.goo.gl/hPzrLsKoy9SG4Vom7

Immediate temp measurements show around 118-120F on the seat back on high, 104-106F on low, and similar on the seat bottom. You could decrease this by going to a lower value series resistor.
 

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Discussion Starter #4
Is this a thing for more recent models? My 2017 model seems to get nicely cosy.

Take an infrared heat gun to the seat to get a dispassionate measurement of how hot its actually getting. You may be surprised on how "hot" the seat isn't.



I freely admit that I have only done direct temperature measurements on my Bolt (although on 4 seats in the one Bolt), so yours might vary. And I "might" have a 6 sigma extreme on all 4 seats with abnormally low heated seat output... but based based on the local dealerships responses and online searches ... I know I'm not alone in this complaint.



However, if you do direct dispassionate measurements and find your seat is lacking heat output, this is still a way to optimize things for your personal liking.



If you are in a temperate climate, the OEM nominal body temp seat temps may seem "hot", because your body is trying to shed heat to maintain core body temps, and thus appear "hot". But in seriously cold climates like where I live, having seats that actually get above body temp are a great way to stay warm without using a lot of HVAC energy. And every single one of my heated seats in my 2018 Bolt failed to get above body temp when using direct dispassionate measurements. Yes, they were "heated" and do get "warm", but not enough to add heat to the body.


Compared to my BMW and Honda and the Bolt's heated steering wheel, all of which approach 120F, the OEM Bolt seats getting to low/mid 90's on "high" was a huge disappointment.
 

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Discussion Starter #5
Don't think so as my 19 is the same as yours.

How do you know its the same? "nicely cozy" isn't a quantifiable measurement... Have you directly measured the surface temperature of your seats? I'd love to see some measurements from other Bolt owners to compare to my measurements, and those from other late model GM vehicles, that show pathetic heat output.
 

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An asside on the term Nanny State

Sorry to be way off topic, but I'm curious why you used the term "Nanny State" in the original post when in fact it was private individuals suing a private company that caused the situation you are complaining about. And the damage payments were awarded by 12 person juries of non-governmental employees. I've lived in other countries where government magistrates have a lot more power to dismiss cases. In my experience there are many fewer damage awards made to stupid people when the "state" is more involved.

So ... looks to me like the blame lies with the people, rather than the state.
 

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Sorry to be way off topic, but I'm curious why you used the term "Nanny State" in the original post when in fact it was private individuals suing a private company that caused the situation you are complaining about. And the damage payments were awarded by 12 person juries of non-governmental employees. I've lived in other countries where government magistrates have a lot more power to dismiss cases. In my experience there are many fewer damage awards made to stupid people when the "state" is more involved.

So ... looks to me like the blame lies with the people, rather than the state.
Fair comment. Perhaps the term “state” is being used in the context of “culture” or “society” rather than “government”.
 

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How do you know its the same? "nicely cozy" isn't a quantifiable measurement...
I can't speak for Cataract2, but I can't leave the heated seats on "high" for more than about 5 or 10 minutes because they become uncomfortably hot - so once they've warmed up I turn them from "three dot" (high) down to "two dot" (medium) strength. That's wearing denim jeans. If you're wearing really warm clothing it might be harder for the heat to penetrate.

And just a quick sanity check - do you have the seats on "manual" mode? I found that "automatic" mode didn't provide enough heat for me, so I disabled it.
 

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I've never had an issue with my '17 Bolt's heated seats. Whenever I do turn on the seat heaters manually, I never set them higher than 1.
From the "seat of the pants" feel, my '12 Volt's heated seats do seem a bit stronger than my Bolt's, but the Bolt's seats still supply plenty of heat for me.
 

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Discussion Starter #11
Any chance of getting a higher resolution photo of the controller with the resistors added? Nice mod and explanation!
Thanks.

You should be able to zoom in on the fairly high resolution pics int he google link. Hopefully that's enough. A quick verbal description is the thermistor leads for the driver seat are on the outside row, 3rd ones in from each side. I placed black marker "dots" on the driver thermistor leads in one of the pics that's easy to see when you zoom in. The zoom in should also show you the leads being cut and separated. The resistors just bridge across the cut leads (one terminal on each side of the cut lead).

The larger connector has fatter leeds and carry the switching FETs current that goes to the actual heating elements.

It was -10F this morning on the drive to work. I had to turn down the seat heat setting to 2 instead of 3 as my back side was getting too hot. And this is with a heavy winter parka. Before this mod I couldn't tell if the seat was even on when wearing winter clothing due to the pathetic heat output.
 

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Discussion Starter #12
Sorry to be way off topic, but I'm curious why you used the term "Nanny State" in the original post when in fact it was private individuals suing a private company that caused the situation you are complaining about. And the damage payments were awarded by 12 person juries of non-governmental employees. I've lived in other countries where government magistrates have a lot more power to dismiss cases. In my experience there are many fewer damage awards made to stupid people when the "state" is more involved.

So ... looks to me like the blame lies with the people, rather than the state.
Good points. I do agree a lot of the blame lies with the people, and their lack of ability to take responsibility for their own choices, and desire to take money/resources from others out of greed/desperation. And the lawyers. And the legal system in general where the government allows for ridiculous lawsuits to take place at all.

I used the term Nanny State in reference to the fact that the "state", or government in general, would allow such a lawsuit to take place. A heated seat is supposed to get hot. Much like the famous McDonalds hot coffee lawsuit ... coffee is supposed to be hot. People who use hot things that don't take precautions with those things should have to deal with the outcome of their own choices.

The fact that there were enough mouthbreathers to fill a jury and award the plantiff someone elses money for not taking normal precautions with "hot" things is ridiculous. And one of the outcomes of that ridiculousness is automakers are making their heated seats less hot. Which sucks for those of us in extremely cold climates where HOT heated seats are a wonderful thing.
 

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Discussion Starter #13
I can't speak for Cataract2, but I can't leave the heated seats on "high" for more than about 5 or 10 minutes because they become uncomfortably hot - so once they've warmed up I turn them from "three dot" (high) down to "two dot" (medium) strength. That's wearing denim jeans. If you're wearing really warm clothing it might be harder for the heat to penetrate.

And just a quick sanity check - do you have the seats on "manual" mode? I found that "automatic" mode didn't provide enough heat for me, so I disabled it.
They will come on "automatically" depending on temp, and vary on the setting depending on vehicle temp (sometimes they are on 0,1, 2 or 3, depending on how cold the car is). But I override the settings by hitting the button, which takes it out of automatic mode and puts it into manual mode. I had read a post on here months ago that suggested manual mode as a way to improve heat output. It didn't do anything on my car to increase heat out, as measured with a temp gun to find the actual surface temp.

Would you be able to take some measurements of your seat surface temps to compare? I hear a lot of people talking in subjective terms about their seat heat output, but no direct measurements are being given except for what I posted. It would be interesting to see what kind of spread in temps exist from vehicle to vehicle, or if there's a difference in peoples perceptions of what "feels" hot.

NOTE: I should put this in the first post... but always disconnect the 12V battery for awhile before messing with seat connectors due to airbags in the seats...
 

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Take an infrared heat gun to the seat to get a dispassionate measurement of how hot its actually getting. You may be surprised on how "hot" the seat isn't.
I will try that this week, just to see what measurements I get.
However, I agree with Sean Nelson, 3 dots is to hot for comfort.
It takes longer, but I can feel definite heat, even through a 1/2” sheared sheepskin cover. I too turned off the AUTO HEAT selection, anyone in passenger seat turns it on manually, & so far everyone thinks 3 dots is too warm. The Bolt seems to be at the same level as my Benz, which is also to hot if turned fully up.
I’m not sure the infrared measurements are valid. The heating grid is below the top surface of the seat. When you sit on it, the top fabric & foam compresses, essentially making the substrate more dense, which transfers the heat better, & creates a better “heat sink”.
As soon as you get out of the seat, the material expands, & fabric, having little density or thermal mass, cannot retain much heat. Within seconds,(especially on a cold day with a large temperature delta), the seat cover will cool considerably.
Have you tried placing a thermometer on the seat, with a weighted blanket on top, (simulating your azz), to see what the temp reads?
Also remember that you don’t need 98.6F to feel warm, or to “add heat”. That value is basal temp, your core temp. Skin temp, especially top of arms & legs can be considerably lower.
I don’t think the Canadian models use a different controller or heat element, but the few times I’ve tried it on my 2018 LT, 3 dots is too much.
 

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Discussion Starter #16
I will try that this week, just to see what measurements I get.
However, I agree with Sean Nelson, 3 dots is to hot for comfort.
It takes longer, but I can feel definite heat, even through a 1/2” sheared sheepskin cover. I too turned off the AUTO HEAT selection, anyone in passenger seat turns it on manually, & so far everyone thinks 3 dots is too warm. The Bolt seems to be at the same level as my Benz, which is also to hot if turned fully up.
I’m not sure the infrared measurements are valid. The heating grid is below the top surface of the seat. When you sit on it, the top fabric & foam compresses, essentially making the substrate more dense, which transfers the heat better, & creates a better “heat sink”.
As soon as you get out of the seat, the material expands, & fabric, having little density or thermal mass, cannot retain much heat. Within seconds,(especially on a cold day with a large temperature delta), the seat cover will cool considerably.
Have you tried placing a thermometer on the seat, with a weighted blanket on top, (simulating your azz), to see what the temp reads?
Also remember that you don’t need 98.6F to feel warm, or to “add heat”. That value is basal temp, your core temp. Skin temp, especially top of arms & legs can be considerably lower.
I don’t think the Canadian models use a different controller or heat element, but the few times I’ve tried it on my 2018 LT, 3 dots is too much.

Thanks. I look forward to your measurements.


I wonder if some of the variability is between the leather seats in a Premiere and the cloth seats in the LT? Although we'd need some actual measurements from more owners to know this... Are those of you who have "hot" heated seats in an LT or Premiere?



Agree on the rapid cooling when getting out of the seat. I mentioned the initial seat surface temps being hotter than what the pics show from the infrared heat gun. And the temps do drop rapidly. The hottest measurements of ~120F came from doing a quick lean forward and shooting at the seat back within 1 second. But with the OEM seat heater control module setup the seats would only get to ~95F with this quick measurement, which is roughly what skin temp is for a normal ambient situation for most humans, so my seats weren't "adding" much of any heat: http://www.healthyheating.com/Definitions/facts_about_skin.htm


The emissivity of leather is basically the same as human skin, so the temps from the infrared heat gun should be accurate.

https://www.optotherm.com/emiss-table.htm


I'm not sure of the material in the LT seats and what is its emissivity, so a heat gun could give false readings on that fabric.
 

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I used the term Nanny State in reference to the fact that the "state", or government in general, would allow such a lawsuit to take place. A heated seat is supposed to get hot. Much like the famous McDonalds hot coffee lawsuit ... coffee is supposed to be hot. People who use hot things that don't take precautions with those things should have to deal with the outcome of their own choices.

The fact that there were enough mouthbreathers to fill a jury and award the plantiff someone elses money for not taking normal precautions with "hot" things is ridiculous. And one of the outcomes of that ridiculousness is automakers are making their heated seats less hot. Which sucks for those of us in extremely cold climates where HOT heated seats are a wonderful thing.
It's my experience that people generally have this opinion when they are unfamiliar with the actual details of the case.

The woman suffered third-degree burns all over her pelvis from the coffee. She was in the hospital for days receiving skin grafts. At the temperature at which the coffee was served (190), it only takes a few seconds to get 3rd degree burns. She was permanently disfigured. Coffee is supposed to be hot, yes, but not so hot that it will change your life forever if you spill it.

I don't think one needed to be a "mouthbreather" to find that justice in this case involved finding that McDonalds was partially responsible (which is what the jury found).
 

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Discussion Starter #18
It's my experience that people generally have this opinion when they are unfamiliar with the actual details of the case.

The woman suffered third-degree burns all over her pelvis from the coffee. She was in the hospital for days receiving skin grafts. At the temperature at which the coffee was served (190), it only takes a few seconds to get 3rd degree burns. She was permanently disfigured. Coffee is supposed to be hot, yes, but not so hot that it will change your life forever if you spill it.

I don't think one needed to be a "mouthbreather" to find that justice in this case involved finding that McDonalds was partially responsible (which is what the jury found).

Since you seem to want to steer the thread way off topic yet again ... The woman spilled the coffee on herself while attempting to balance the cup between her knees and trying to remove the lid. McDonalds didn't dump the coffee in her lap. She dumped the coffee in her lap. The cup had warnings about the contents being hot. It wasn't her first cup of coffee from McDonalds that she had consumed.



For those unfamiliar with the details, this is a quick synopsis: https://en.wikipedia.org/wiki/Liebeck_v._McDonald's_Restaurants


It at least gives me hope for humanity that some non mouthbreathers exist who know enough to dismiss such a ridiculous lawsuit.
Similar lawsuits

In McMahon v. Bunn Matic Corporation (1998), Seventh Circuit Court of Appeals Judge Frank Easterbrook wrote a unanimous opinion affirming dismissal of a similar lawsuit against coffeemaker manufacturer Bunn-O-Matic, finding that 179 °F (82 °C) hot coffee was not "unreasonably dangerous".[26]
In Bogle v. McDonald's Restaurants Ltd. (2002), a similar lawsuit in England failed when the court rejected the claim that McDonald's could have avoided injury by serving coffee at a lower temperature.[27]
Since Liebeck, major vendors of coffee, including Chick-Fil-A,[28] Starbucks, Dunkin' Donuts, Wendy's, Burger King,[29] hospitals,[30] and McDonald's[31] have been defendants in similar lawsuits over coffee-related burns.
 

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NOTE: Always disconnect the 12V battery for awhile before messing with seat connectors due to airbags in the seats...

One of my grips with the Bolt used to be due to the pathetic amount of "heat" the "heated seats" would create. The heated steering wheel is great and will get up to ~120F, which will add heat into the body. The OEM Bolt seats would not even get above body temp, so they don't really "add" warmth to the occupants. And the amount of heat was far less than any of my other vehicles with heated seats.
Sorry if this is a bit off topic, but since you have been working with the seat heaters you might be able to give me some advice.

The heated rear seat on the driver's side stopped working. If you push the button to activate nothing happens. The indicator light doesn't even come on.

My 2017 Bolt has 46,000 miles and is out of warranty for this. Could it be something as simple as a fuse? If so, do you know which one to check?
 

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Discussion Starter #20
Sorry if this is a bit off topic, but since you have been working with the seat heaters you might be able to give me some advice.

The heated rear seat on the driver's side stopped working. If you push the button to activate nothing happens. The indicator light doesn't even come on.

My 2017 Bolt has 46,000 miles and is out of warranty for this. Could it be something as simple as a fuse? If so, do you know which one to check?
I haven't messed with the rear seats, so I have no specific info to share. Sorry. But based on your description, checking the fuse sounds like a good place to start.

There are good youtube videos that show and describe the diagnosing and fixing of heated seat issues. That should be helpful if something simple like the fuse doesn't fix things. There's several things that can go wrong, but if you're somewhat mechanically inclined, have the time and some simple tools it's generally a DIY to find and fix the problem.
 
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