Heated Seats Description and Operation KA1

The driver and passenger heated seats have 2 heat zone operating modes with 3 heat level modes and will operate only while the engine is running. The heat zones are determined by which of the 2 heated seat buttons are pressed, while the heat level is determined by the number of times they are pressed. Pressing the seat cushion button 1 time will activate the seat back and cushion heater elements in the high mode. Each time the seat cushion button is pressed the seat back and cushion heat level is reduced from high to medium, low, and off. Pressing the heated seat back button 1 time will activate only the seat back heater element in the high mode. Each time the seat back button is pressed the seat back heat level is reduced from high to medium, low, and off. During heated seat operation the heat zone operating mode may be changed without affecting the current heat level mode. During a cold ambient remote start activation the heated seats will turn on.

The heated seat switches are an integrated to the HVAC control head and when a heated seat switch is pressed the active switch signal is sent to the memory seat module as a GMLAN message. The memory seat module determines the heated seat mode based on the switch messages and sends a message to the HVAC control head to display the heated seat indicators as necessary.

The heated seat switches are momentary contact switches and are inputs to the driver and passenger door switches. A ground circuit is connected to the switch assembly through the door switch, and when a heated seat switch is pressed and released a brief switch signal is supplied to the door switch. Whenever the door module receives an active heated seat switch input, the active switch signal is sent to the memory seat module as a GMLAN message. The memory seat module determines the heated seat mode based on the switch messages and sends a message to the door switch to display the heated seat indicators as necessary.

The memory 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 pulse width modulation (PWM) low side drive control circuits. During heated seat operation both the seat back and cushion heater elements are supplied battery voltage. The seat module grounds the appropriate control circuits for back only or back and 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 4 independent inputs from thermistors located in the seat back and seat cushion of the driver and passenger 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 modules allow heated seat operation only while the engine is running which is determined by a GMLAN serial data circuit message.

Heated Seats Description and Operation KA6

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.