Heated/Cooled Seat Switch and Door Module

The driver and front passenger seats are controlled by a separate heated/cool seat switch. Ground is supplied to the heated/cool seat switch through the low reference circuit and the respective door module. The door module plays an important part of the climate control seat (CCS) operation, first by relaying the selected switch inputs to the CCSM, and second, by controlling the mode and temperature indicators of the heated/cool seat switch.

The following describes the sequence of operation of the heated/cool seat switch, and how the door module responds to each of the switch inputs.

• High Temperature-When either the heat or cool seat switch is pressed once, ground is applied through the switch contacts and the switch signal circuit to the door module. In response to this signal, the door module then sends a message via GMLAN serial data to the memory seat module (MSM). In response to this message, the MSM then sends a pulse width modulation (PWM) signal through the heated/cool seat mode signal circuit to the CCSM indicating the switch input. The door module then applies a ground through the appropriate heat or cool seat indicator control circuit to the switch, illuminating the selected heat or cool mode indicator. At the same time, the module also applies a ground through the high, medium, and low temperature indicator control circuits of the switch illuminating all 3 temperature indicators, indicating the high temperature mode.
• Medium Temperature-When the switch is pressed a second time, the door module signals the CCSM of the medium temperature request. The door module then removes the ground from the high temperature indicator, leaving the medium and low temperature indicators illuminated, indicating the medium temperature mode.
• Low Temperature-When the switch is pressed a third time, the door module signals the CCSM of the low temperature request. The door module then removes the ground from the medium temperature indicator, leaving the low temperature indicator illuminated, indicating the low temperature mode.
• System Off State-After the switch is pressed a fourth time, the door module signals the CCSM of the system OFF request. The door module then removes the grounds from indicator control circuits turning OFF the appropriate heat or cool mode indicator and the low temperature indicator.
• Seat Back Only Heat Mode-The back only mode will operate only in the heat mode in any one of the above mentioned temperature settings. When the back only switch is pressed once, the door module signals the CCSM of the back only mode request. The door module then supplies a ground through the seat back only mode indicator control circuit to the switch, illuminating the BACK ONLY mode indicator.