DESCRIPTION AND OPERATION
4.28 RANGE ROVER
FRONT HEATED SEATS
DESCRIPTION
General
Operation of the front electric seats is controlled by the Automatic Temperature Control
(ATC) ECU via the two centre console mounted switches. Pressing the relevant seat heat
switch once will heat the seat to a temperature of 44 °C (111 °F) and illuminate two LED's
on the switch face. Pressing the seat heat switch a second time will lower the temperature
to 39 °C (102 °F) and illuminate one LED on the switch face. Pressing the switch a third time
switches off the seat heat function and extinguishes the remaining LED.
OPERATION
Power Distribution
Feed from the positive battery terminal (C0192) is supplied to fuse 12 and fuse 52 of the
passenger compartment fuse box (C0632) on an N wire. Fuse 12 (C0586) provides a
constant battery feed to the ATC ECU (C1629) on an RP wire. Fuse 52 (C0582) provides a
constant battery feed to the ATC ECU (C0249) on a PU wire. The ATC ECU (C1630) is
earthed on an N wire.
RH Seat
When the non-latching RH seat heat switch is pressed, the ATC ECU (C0249) provides a
feed to the cushion heater matrix (C0969) and the backrest heater matrix (C0971) on GY
wires. Both matrices are earthed on N wires.
The ATC ECU (C1629) monitors the temperature of the cushion heater matrix (C0969) by
providing a feed to a Negative Temperature Coefficient (NTC) sensor on a WU wire. The
sensor is earthed on an N wire. By calculating the resistance of the NTC sensor, the ATC
ECU can determine the temperature of the seat and regulate the supply voltage to the heater
matrices accordingly.
LH Seat
When the non-latching LH seat heat switch is pressed, the ATC ECU (C0249) provides a
feed to the cushion heater matrix (C2090) and the backrest heater matrix (C2091) on GP
wires. Both matrices are earthed on N wires.
The ATC ECU (C1629) monitors the temperature of the cushion heater matrix (C2090) by
providing a feed to a Negative Temperature Coefficient (NTC) sensor on a WG wire. The
sensor is earthed on an N wire. By calculating the resistance of the NTC sensor, the ATC
ECU can determine the temperature of the seat and regulate the supply voltage to the heater
matrices accordingly.
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