Circuit/System Description
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2011 GMC Yukon XL, 2011 GMC Yukon, 2011 Chevrolet Tahoe, 2011 Chevrolet Suburban, and 2011 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.
The front seat heating elements are controlled by a common high current relay internal to the rear heated seat control module (RHSM) and on the low side by individual element control circuits. The RHSM connects the seat heater element supply voltage circuits to a common reference point. This reference point is biased to approximately 2.5 V. Before the RHSM will allow heated seat operation, it checks to see if the heating element supply voltage circuits and control circuits are shorted to ground or battery voltage. Once the RHSM 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 circuit.