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 ******* 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.
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 ******* 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.