L322 Range Rover System Description and Operation
SEATS
76-5-6
DESCRIPTION AND OPERATION
The mechanical sub-system comprises the following components:
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Gear wheels
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Rack and pinion assemblies.
Seat Power Relay
Located in the passenger compartment fusebox, the seat power relay supplies battery voltage for seat adjustment.
The motors are energised when a selection is made.
Seat Switch Pack
Each seat switch pack, mounted on the seat valance, provides movement in the following axes:
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Seat forward/backward adjust
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Seat height adjustment
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Seat angle adjustment
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Backrest angle adjustment
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Backrest head adjustment
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Head restraint height adjustment.
Manual adjustment of the seat position can be carried out at any time, having priority over memory recall. The control
unit sequences the order of adjustment.
Seat Forward/Backward Motor
The seat forward/backward motor is a permanent magnet motor coupled to a rack and pinion assembly. Should the
motor seize or stick for 6 seconds or more, an internal thermal cut-out switch will trip to remove voltage from the motor.
Reset time for the switch is 35 seconds. Two pins within the seat switch pack control the seat forward/backward motor.
Both pins are normally earthed. Operating the backward switch applies voltage to that pin while the other pin remains
earthed. Operating the forward switch reverses power and earth to the motor allowing the motor to run in the opposite
direction.
Seat Cushion Front Up/Down Motor
The seat cushion front up/down motor is a permanent magnet motor coupled to a rack and pinion assembly. Should
the motor seize or stick for 6 seconds or more an internal thermal cut out switch will trip to remove voltage from the
motor. Reset time for the switch is 35 seconds. Two pins within the seat switch pack control the seat cushion front up/
down motor. Both pins are normally earthed. Operating the up switch applies voltage to that pin while the other pin
remains earthed. Operating the down switch reverses power and earth to the motor allowing the motor to run in the
opposite direction.
Seat Cushion Rear Up/ Down Motor
The seat cushion rear up/down motor is a permanent magnet motor coupled to a rack and pinion assembly. Should
the motor seize or stick for 6 seconds or more, an internal thermal cut out switch will trip to remove voltage from the
motor. Reset time for the switch is 35 seconds. Two pins within the seat switch pack control the seat cushion rear up/
down motor. Both pins are normally earthed. Operating the up switch applies voltage to that pin while the other pin
remains earthed. Operating the down switch reverses power and earth to the motor allowing the motor to run in the
opposite direction.
Seat Squab Forward/Backward Motor
The squab forward/backward motor is a permanent magnet motor coupled to a rotary rack and pinion assembly.
Should the motor seize or stick for 6 seconds or more, an internal thermal cut out switch will trip to remove voltage
from the motor. Reset time for the switch is 35 seconds. Two pins within the seat switch pack control the squab fore/
aft motor. Both pins are normally earthed. Operating the fore switch applies voltage to that pin while the other pin
remains earthed. Operating the aft switch reverses power and earth to the motor allowing the motor to run in the
opposite direction
Lumbar Pump
The lumbar pump inflates a bladder in the squab which provides extra support for the seat occupant. With no load on
the seat it takes approximately 10 seconds to completely inflate the bladder. With a load of 25 kg (55 lb) it takes
approximately 15 seconds to inflate the bladder. A pressure cut off switch in the system will operate at 0.12 to 1.93
bar (1.8 to 28 lbf.in
2
). The lumbar bladder can be replaced independently of the pump. The components are not
serviceable.