Heated Seat Components
The rear heated seat system has one control module that controls heat operation for both the left and right rear seat. The rear heated seat consists of the following components:
| • | Rear auxiliary HVAC control module |
| • | Right heated seat switch |
| • | Left seat cushion heating element |
| • | Left seat back heating element |
| • | Left seat cushion temperature sensor |
| • | Right seat cushion heating element |
| • | Right seat back heating element |
| • | Right seat cushion temperature sensor |
| • | REAR HTD SEATS Fuse 20 A |
Power and Grounds
Battery positive voltage is supplied to the rear heated seat module through the ignition 3 voltage circuit and the REAR HTD SEATS Fuse that is located in the left rear fuse block. This voltage is used to power up the heated seat module and to supply
power to the seat heater elements. This voltage supply allows the heated seat system to operate only with the ignition switch in the ON position. The rear heated seat module is grounded through the module ground circuit and G402.
Modes of Operation
There is 1 mode available for heated seat operation, both the seat cushion and seat back heat turn on and off together. When a heated seat temperature signal request is received, the heated seat module will activate both the seat cushion and seat back
heating elements.
Heated Seat Switch/LED Indicators and Operation
The left and right rear heated seats are controlled by separate heated seat switches both located in the rear climate control panel (RCCP). Battery positive voltage is supplied to the RCCP by the rear heated seat module. The rear heated seat module controls
the heated seat operation for both, the left and right rear heated seats, and the heated seat switch temperature indicators.
The following describes the sequence of operation and how the heated seat module responds to each of the switch inputs.
| • | High Temperature--When the heated seat switch is pressed once, battery positive voltage is applied through the switch contacts and the switch signal circuit to the heated seat module indicating the high heat request. In response to this signal,
the module applies battery positive through the heating element supply voltage circuits to the seat cushion and seat back heating elements. At the same time, it activates the low side drivers that supply a ground through the heating element control circuits
to the seat heating elements. The module then applies a ground through the high temperature indicator control circuit illuminating the high temperature indicator to indicate the high temperature mode. |
| • | Medium Temperature--When the switch is pressed a second time, the heated seat module sets the temperature level to medium heat. Then it removes the ground from the high temperature indicator and applies ground to the medium temperature indicator
to indicate the medium temperature mode. |
| • | Low Temperature--When the switch is pressed a third time, the heated seat module sets the temperature level to low heat. Then it removes the ground from the medium temperature indicator and applies ground to the low temperature indicator to
indicate the low temperature mode. |
| • | System OFF State--When the switch is pressed a fourth time, the heated seat module removes the battery voltage and grounds from the heating elements. Then it removes the ground from the low temperature indicator, indicating the system OFF state. |
Temperature Regulation
The heated seat system is designed to warm the seat cushion and seat back to approximately 42°C (107.6°F) when in the high position, 39.5°C (103°F) when in the MED position, and 37°C (98.6°F) when in the low position. The heated
seat module monitors the seat temperature through the temperature sensor signal circuit and the temperature sensor (thermistor) which is located in the seat cushion. The temperature sensor is a variable resistor, it's resistance varies as the temperature of
the seat changes. When the temperature sensor resistance indicates to the heated seat module that the seat has reached the desired temperature, the module opens the ground path of the seat heating elements through the heated seat element control circuit. The
module will then cycle the low side driver element control circuits open and closed in order to maintain the desired temperature.
