Yukon Denali 2WD V8-6.0L Hybrid (2010)
Circuit/System Description
The heat and cool seat functions for the driver and passenger seats are controlled by the climate control seat module (CCSM) that is located under the
passenger seat cushion. When a driver or passenger heat or cool seat switch is pressed, a low reference signal is applied through the switch signal circuit
to the door lock/window switch. In response to the switch input, the door lock/window switch simultaneously illuminates the appropriate heated/cooled
switch indicators and sends a serial data message to the memory seat module (MSM) indicating the heat or cool seat request. The MSM then sends a
pulse width modulation (PWM) signal through the appropriate heated/cooled seat mode signal circuit to the CCSM. The CCSM then applies battery
positive voltage to the seat cushion and seat back thermal electronic devices (TEDs) and a pre-determined voltage to the blower motors. To determine
seat temperature, the CCSM supplies a 5 V signal and a low reference to the temperature sensors that are attached to each TED. The temperature sensors
are variable resistors, their resistance changes as the temperature of the seat changes. Then based on the seat temperature, the CCSM controls the voltage
level that it applies to the TEDs and blower motors.
Diagnostic Aids
The following conditions must be met in order to perform valid tests when diagnosing the climate control seat system:
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The ignition must be cycled OFF then ON between each test in order to reset the CCSM.
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Most circuit faults will set a DTC within 1.5 minutes. However, some circuit faults may cause a performance problem in one mode and be
inoperative and set a DTC in another mode. In some cases it may take 5 minutes or more for a DTC to set. Operate the heated/cooled seat in each
of the three modes for 5 minutes or more then check for DTCs.
