Sierra 2500 Denali 2WD V8-6.0L (2011)
Seat Heater: Description and Operation
Heated/Cooled Seats
Heated/Cooled Seats Description and Operation
The driver and front passenger heated cooled seat system consist of the following components:
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Seat cushion heat/cool ventilation module
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Seat back heat/cool ventilation module
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Climate control seat module
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Memory seat module
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Heated and cooled seat switch
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Door lock/window switch
Air Circulation
When the heated/cool seat switch is pressed to initiate operation of the climate control seat system, cabin air is drawn through the heated/cool ventilation
module air filter, then directed through passages in the foam of the seat cushion and seat back to the seat's occupant. In order for the climate control seat
system to operate to its optimum performance, it is crucial to have unrestricted air flow through the system. A dirty or restricted air filter, the blockage of
an exhaust air duct, a misaligned heated/cool ventilation module, or incorrect foam installation of the seat cushion or seat back will all have negative
effects on climate control seat system operation.
Seat Heat/Cool Ventilation Module
Each heated/cool seat has 2 ventilation modules, one located under the seat cushion and one located in the seat back. These modules are controlled by
the climate control seat module (CCSM). Each ventilation module contains a thermo-electric device (TED), a temperature sensor, and a blower motor.
The TED and temperature sensor are mounted downstream of the blower motor. Each TED consists of a circuit of positive and negative connections
sandwiched between 2 ceramic plates. Each ceramic plate is equipped with copper fins for heat exchange. The air flowing past these fins is either
directed as conditioned air into the seat cushion and seat back, or directed into the cabin as waste air.
TED is essentially a solid state heat pump that is used to heat or cool the air supply to the seat cushion and seat back. When voltage is applied to a TED,
one side releases energy as heat, while the opposite side absorbs energy and gets cold. When the polarity of the current flow to the TEDs is switched, the
hot and cool sides of the TED reverse.
During the following climate control seat system description and operation, the TEDs, blower motors, and temperature sensors will be referenced
independently even though they are all packaged together as a module.
Climate Control Seat System
The climate control seat system consists of two heated/cool ventilation modules and one CCSM that controls both the driver and passenger heated/cool
seats systems. The CCSM is mounted below the front passenger seat cushion.
Once a climate control seat system is activated, cabin air is drawn through the seat blower motors and directed across the fins of each of the TED located
under the seat cushion and in the seat back. The air is either heated or cooled as it passes over the TEDs. This conditioned air is then directed through
channels in the foam of the seat pad and through small holes in the seat cover to the occupant. Once the system is activated, the CCSM uses a set of
algorithms to control the temperature of the selected heating or cooling modes.
Climate Control Seat Module Power and Ground
Battery positive voltage is supplied at all times to the CCSM through the battery positive voltage circuit and a 30 A fuse that is located in the I/P fuse
block. This voltage is used by the CCSM to supply power to the TEDs and the blower motors. Ignition voltage is also supplied to the CCSM through the
ignition voltage circuit and a 10 A fuse located in the underhood fuse block. The ignition voltage is used to power up the CCSM and allows the climate
control seat system to operate only with the ignition in the ON position. The CCSM is grounded through the module ground circuit and G304.
Climate Control Seat Module
The CCSM is located under the passenger seat and controls 4 individual driver and passenger seat heat/cool ventilation blowers. When the CCSM
receives a heated cooled seat command through the left or right heated/cooled seat mode signal circuit, the appropriate seat heat/cool ventilation blowers
will be operated by the CCSM.
Memory Seat Module
The memory seat module (MSM) monitors the heated cooled seat switches through serial data message inputs and determines the heated cooled seat
operating modes and temperature levels. The MSM controls the operating mode of the CCSM through 2 pulse width modulation (PWM) signal circuits.
The left and right heated/cooled seat mode signal circuits are referenced from battery voltage by the CCSM and pulsed low by the MSM. Each heated
