Circuit/System Description
WARNING: This page is about a different car, the 2007 Suzuki XL7. However, it is still accessible from the selected car via links, so may be relevant.
The heated seat heating elements are controlled by a common high current relay internal to the heated seat module and by individual low side element control circuits. The heated seat module connects the heater element supply voltage circuits for both seats to a common reference point. This reference point is biased to approximately 2 volts. Before the heated seat module will allow heated seat operation, it checks to see if the heating element supply voltage circuits and control circuits are shorted to ground or voltage. Once the module verifies that it is not closing into a shorted heating element, it allows heated seat operation. After which it continues to monitor for a shorted a circuit.