Circuit/System Description
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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.