Front Seats - System Operation and Component Description

The SCME monitors seat cushion temperature while it supplies voltage and ground to both blower motors. The SCME also supplies a variable voltage signal to control the blower speed. Cabin air enters the blower through a filter attached to the blower motor housing. Heated or cooled air exits the blower motor and flows through the foam pad.

Climate Controlled Seat Heating Characteristics

In heat mode, the blower motor can add up to 40–60° C (72–108° F) to the ambient inlet air temperature.

The system control settings are indicated next to each climate controlled seat heat button on the touchscreen. The first setting is HIGH (3 indicators), the second setting is MED (2 indicators) and the third is LOW (1 indicator), then OFF (no indicators).

When heating, the SCME varies the speed of the blower motors and the duty cycle of the integral Thermo- Electric Device (TED) in order to reach and maintain the desired temperature determined by the system control settings.

Climate Controlled Seat Cooling Characteristics

In cool mode, the blower motors can remove up to 8° C (14° F) from the ambient air temperature entering the system.

The system control settings are based on the 3 indicators next to each climate controlled seat cool button on the touchscreen. The first setting is HIGH (3 indicators), the second setting is MED (2 indicators) and the third is LOW (1 indicator), then OFF (no indicators).

The SCME maintains a constant blower motor speed and a constant Thermo-Electric Device (TED) supply voltage (duty cycle is determined by the switch setting) in COOL mode.

Climate Controlled Seat Recovery Mode

If the temperature of one of the blower motors rises above 110° C (229.8° F) in the heat mode or 65° C (148.9° F) in the cool mode for more than 4 seconds, the SCME records an overtemperature DTC, removes voltage from the Thermo-Electric Devices (TEDs) (part of the blower motor assembly) and goes into recovery mode (blower only) for 30 seconds to cool down the blower motor. The same occurs if a temperature difference of 60° C (108° F) or greater is detected between the backrest and cushion blower motors on either front seat. The SCME continues to monitor the blower motors while in recovery mode. If the temperature of the Thermo-Electric Devices (TEDs) do not drop to 105° C (220.8° F) in the heat mode or 60° C (139.9° F) in the cool mode after 30 seconds, the system continues to cool the blower motors in recovery mode for up to 5 minutes. If the Thermo-Electric Devices (TEDs) cool down after 30 seconds, but before 5 minutes (checked at 4 second intervals), the system is operating normally. An overtemperature DTC is still recorded even if the system recovers and is operating normally. This is more likely to occur during extreme cabin temperatures with significant seat back sun load. If the system does not recover within 30 seconds in heat mode or within 5 minutes in cool mode, the SCME disables that seat (fault mode) and remains off until the ignition is cycled. Also, if the SCME detects a temperature differential fault twice during the same ignition cycle, the SCME disables the seat. When a fault causes a shutdown, the climate controlled seat indicators turn off and that seat is not operational until the next ignition cycle.

Component Description

Driver Seat Control Switch - With Memory

The seat control switch is hard-wired to the DSM, which controls seat operation. When a specific seat adjustment position is selected, an individual circuit is switched to voltage.

Seat Control Switch - Without Memory

The seat control switch contains normally closed contacts (which are grounded). When a specific adjustment position is selected, an individual circuit is switched to voltage.