RAM 1500 Truck 4WD V8-5.7L VIN D (2005)
Seat Heater Switch: Description and Operation
The momentary, bidirectional rocker-type heated seat switch (1) provides a resistor-multiplexed signal to the heated seat module via a mux circuit. Each
switch has a center neutral position and momentary Low and High positions so that both the driver and the front seat passenger can select a preferred
level of seat heating. Each heated seat switch has two Light-Emitting Diode (LED) indicator lamps (2), which indicate the selected mode (Low or High)
of the seat heater. These indicator lamps also provide diagnostic feedback for the heated seat system. Each switch also has an incandescent bulb, which
provides dimmer controlled back lighting of the switch when the headlamps or park lamps are on.
The heated seat switches are both mounted in the instrument panel center bezel, located in the lower center of the instrument panel. The two switches are
snapped into the mounting holes of the heated seat switch bezel, and the heated seat switch bezel is secured with screws to the instrument panel center
bezel. The heated seat switches are differentiated by the keyway in the connector receptacle on the backs of the switches and keyway on the switch
housing. The instrument panel wire harness connectors for the heated seat switches are keyed to match the connector receptacles on the switches so that
the two heated seat switches can only be connected to the proper heated seat electrical.
The two LED indicator lamps and the incandescent bulb in each heated seat switch cannot be repaired. If the indicator lamps or back lighting bulb are
faulty or damaged, the individual heated seat switch must be replaced.
The heated seat switches receive battery current through a fused ignition switch output (run) circuit when the ignition switch is in the On position.
Depressing the heated seat switch rocker to its momentary High or Low position provides a hard-wired resistance signal to the heated seat module. This
signal tells the module to energize the heated seat element of the selected seat and maintain the requested temperature setting. If the heated seat switch is
depressed to a different position (Low or High) than the currently selected state, the heated seat module will change states to support the new selection. If
a heated seat switch is depressed a second time, the heated seat module interprets the second input as a request to turn the seat heater OFF.
The High and Low LED indicator lamps in the heated seat switches receive battery current through a fused ignition switch output (run) circuit when the
ignition switch is in the On position. The ground side of each indicator lamp is controlled by the heated seat module. This control of the switch indicator
lamps also allows the module to provide diagnostic feedback to the vehicle operator or technician to indicate heated seat system faults by flashing the
indicator lamps on and off. One side of the incandescent back lighting bulb in each heated seat switch is connected to ground at all times. The other side
of the incandescent bulb is connected to the fused panel lamps dimmer switch signal circuit. These bulbs are energized when the park lamps or
headlamps are turned on, and their illumination intensity is controlled by the panel lamps dimmer switch.
