The driver and front passenger heated seats each consist 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.
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 heat position,
and 37°C (98.6°F) when in the low heat 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 heated seat 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.
Power and Grounds
Battery positive voltage is supplied to the driver and passenger heated
seat modules from the rear fuse block IGN 3 RR Fuse when the ignition
is in the ON position. This voltage is used to power up the module. Battery
positive voltage is also supplied at all times to the heated seat modules
from the rear fuse block; HTDST LF Fuse for the left heated seat module
or HTDST RF for the right heated seat module. This battery voltage
is used by the module to apply voltage to the heating elements. Both modules
are grounded through the module ground circuits to G301. The heated seat switches
are grounded through the switch ground circuits and G201.
Heated Seats
The driver and passenger heated seats are controlled by a separate heated
seat switch. When 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 the heated seat switch illuminating the high temperature
indicator. 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 the heated seat switch illuminating the low temperature
indicator. 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 battery positive voltage from the seat heating elements and the appropriate
temperature indicator. The heated seat module will also turn off the heated
seats 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 then signals the heated seat modules through the heated
seat control module inhibit signal circuit indicating the current load management
level. During load shed level 0, the RIM does not inhibit the operation
of the heated seats. During load shed level 1, the heated seats that
are on 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 heated seat control module 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 deactivate temperature indicators. 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.