L322 Range Rover System Description and Operation
SEATS
DESCRIPTION AND OPERATION
76-5-9
Seat Heater Elements
The seat heater elements are located in the seat cushion and squab. The cushion and squab heater elements are
wired in parallel. Total power consumption at 13.5 volts is approximately 115 Watts. The cushion heater element has
an input feed from the temperature control unit or heater switch and an output to the squab heater element, which
outputs to earth.
Operation
When the seat heater switch is initially pressed High level heating is selected, pressing the switch a second time
selects Low level heating and pressing the switch a third time switches the heating off.
The seat heaters are thermostatically controlled and will operate intermittently to maintain a predetermined
temperature. The indicator lights in the switches will remain illuminated until either the heaters are manually turned
off, or the starter switch is turned off.
CAUTION: The seat heaters consume considerable power from the battery. For this reason, they should
ONLY be operated while the engine is running.
When the seat heater switch is operated, power is supplied to the heater elements in the seat, causing the seat to
heat up. The temperature control unit senses seat temperature via the sensor in the cushion and regulates voltage to
the seat heater elements to maintain a constant temperature.
The heater elements increase and then maintain the seat at a temperature of between 37 and 44
°
C.
Fault Finding
In the self-test mode the switch indicates faults by displaying a flashing code.
The sequence to select test mode is :
1 Press the heating switch with the ignition off
2 With the switch depressed turn on the ignition switch to Position II
3 Release the switch, this activates the self-test mode
4 After 10 seconds the flashing code is displayed.
The flashing code indicates the following faults
l
1 Flash — Switch overtemperature (T > 95
°
C)
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2 Flashes — Short circuit and/or interruption in the sensor
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3 Flashes — Short circuit and/or interruption in the heating elements.
With the switch set to test mode, maximum heating is selected and both lamps are lit. If a fault is identified the heating
is switched off and, after 10 seconds, the left LED switches off , this LED generates the flashing code. If no fault is
detected the LED remains unlit.
To return to the test mode the switch is pressed twice and the sequence starts again. To cancel the test mode the
ignition switch is turned off.
