Alex Lorman had two things: a 2006 4Runner and a desire for year-round posterior comfort. So he picked up some OEM switches. And some commodity seat heaters. And a whole bunch of knowledge along the way!

The project culminated in a custom PCB, primarily as a home for the MOSFETs required to drive 10A per channel to the heaters. And to manage state and the MOSFETs, a Teensy 3.2 was employed.

One interesting aspect of the project was the employment of low-rate PWM to allow the MOSFETs to avalanche while capitalizing on the high resistance of the heated heaters to enable self-regulation. A GitHub repository serves as a clearing house for information and resources related to the product, with two further repos for the PCB and code.