The driver and front passenger heated seat systems each consists of
the following components:
• | Seat Cushion Heater Element |
• | Seat Back Heater Element |
The rear integration module (RIM) is also involved in the operation
of the heated seats.
Power and Grounds
Battery positive voltage is supplied at all times to the driver and
passenger heated seat modules from the rear fuse block; HTDST LF Fuse
for the driver heated seat module, or, HTDST RF Fuse for the passenger
heated seat module. This battery voltage is used by the module to apply voltage
to the seat heating elements. Battery positive voltage is also
supplied to both heated seat modules from the rear fuse block IGN 3
Fuse with the ignition in the ON position. This voltage is used to power up
the module. Both modules are grounded through the ground circuit to G301.
The heated seat switches are grounded through the switch ground circuit and
G201.
Temperature Regulation
The heated seat system is designed in order to warm the seat cushion
and seat back to approximately 107.6°F (42°C) when in the high position,
and 98.6°F (37°C) when in the low position. The heated seat module
monitors the seat temperature through the temperature sensor signal circuit
and the temperature sensor (thermistor) that is located in the seat cushion.
The temperature sensor is a variable resistor, it's resistance changes 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 element control circuit open and closed in order to maintain the desired
temperature.
Heated Seats
The driver and passenger heated seat are controlled by separate heated
seat switches. When the heated seat is off and the heated seat switch is toggled
toward HI/LO, the heated seat high/low signal circuit of the heated seat module
is momentarily grounded through the HI/LO switch contacts. In response to
this signal, the heated seat module applies battery positive voltage to the
seat cushion/back heater elements, setting the temperature level to high
heat. The module also applies battery positive voltage through the heated
seat high temperature indicator control circuit to illuminate the high temperature
indicator of the heated seat switch. When the heated seat switch is toggled
toward HI/LO a second time, the heated seat high/low signal circuit of the
heated seat module is again momentarily grounded through the HI/LO switch
contacts. In response to this second signal, the heated seat module sets the
temperature level to low heat and applies battery positive voltage through
the heated seat low temperature indicator control circuit to illuminate the
low temperature indicator of the heated seat switch. When the heated seat
switch is toggled toward OFF, the heated seat off signal circuit of the heated
seat module is momentarily grounded through the OFF switch contacts. In response
to this signal, the heated seat module removes the battery voltage from the
seat heating elements and the appropriate temperature indicator. The heated
seat module will also turn off the heated seat whenever the ignition switch
is turned to the OFF position.
Load Management
There are 3 levels of load management controlled by the dash
integration module (DIM). The DIM sends the status of load management to
the rear integration module (RIM) via a class 2 message. In response
to this message, the RIM signals the heated seat modules through the heated
seat module inhibit signal circuit indicating the current load management
level. During Load Shed 0, the RIM does not inhibit the operation of
the heated seats. During load shed level 1, the heated seats are cycled
10 seconds on and 10 seconds off, with temperature regulation
still being enforced. During load shed level 2, the RIM will pull the
inhibit signal circuit of the heated seat module to ground. In response to
this signal, the heated seat modules will turn off the heated seats and temperature
indicators that are illuminated. The instrument cluster will display a BATTERY
SAVER ACTIVE message. The ON/OFF status of the heated seats is reported to
the RIM through the heated seat control module status signal circuit by both
heated seat modules.