Heated Seats Description and Operation (KA6)

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The rear passenger heated seats have cushion heat only with 2 heat level modes and will operate only while the engine is running. The left or right cushion is selected by pressing one of the 2 heated seat buttons, while the heat level is determined by the number of times they are pressed. Pressing the seat heat button 1 time will activate the cushion heater elements in the high mode. Each time the seat cushion button is pressed the seat cushion heat level is reduced from high to low, and off.

The heated seat switches are momentary contact switches and are inputs to the rear seat audio module. A ground circuit is connected to the switch assembly through the rear seat audio module. Whenever the rear seat audio module receives an active heated seat switch input, the next heated seat operating mode is determined by whatever the current mode may be. The seat heater elements are controlled by the rear heated seat module using inputs from the rear seat audio through GMLAN serial data circuit messages. The rear heated seat module controls the voltage supply and the ground circuits to the seat heater elements. When a heated seat function is commanded active, the seat module will switch battery voltage to the heater element supply circuits, and ground is provided through low side drive control circuits. During heated seat operation the seat cushion heater elements are supplied battery voltage. The seat module grounds the appropriate control circuits for left or right cushion heating modes, and opens or closes the active control circuits as necessary in order to maintain the desired seat temperature. The seat module relies on 2 independent inputs from thermistors located in the seat cushion of the left and right seats to control heated seat temperatures. The thermistors are 2-wire sensors supplied with a 5-volt referenced signal circuit and a low reference circuit from the seat module. Resistance through the thermistors varies with temperature causing the heated seat sensor signal circuit voltage levels to decrease as the seat back temperatures rise. The seat module allows heated seat operation only while the engine is running which is determined by a GMLAN serial data circuit message.