Description - Electric Seats
Description - Electric Seats
General
All markets use the same electric seat system. Electrically operated lumbar support is optional. The system consists of an electrical sub-system and a mechanical sub-system.
The electrical sub-system consists of the following components:
- BCU.
- Seat power relays.
- Seat switch packs.
- Seat fore/ aft motors.
- Seat cushion front up/ down motors.
- Seat cushion rear up/ down motors.
- Seat squab motor.
- Lumbar pump.
- Lumbar deflate solenoid.
The mechanical sub-system consist of the following components:
- Gear wheels.
- Rack and pinion assemblies.
Seat power relay
Located beneath the seat, the seat power relay supplies battery voltage to the satellite fuse box. Operation of the relays is controlled by the BCU.
Voltage to the seat power relays is from fuse 5 in the engine compartment fuse box. The BCU controls the earth for the relay coils. Operating the seat power relays provides voltage to the satellite fuse box under each seat.
Satellite fuse box
Located beneath the seat, the satellite fuse box provides circuit protection for the wiring to the seat switches and motors. It also protects the lumbar inflate and deflate circuits.
The seat power relay provides voltage directly to the 40A fuse in the satellite fuse box. Voltage from this fuse feeds the seat switch pack. The 3A fuses in the satellite fuse box protect the wiring to the lumbar pump and lumbar deflate solenoid. Voltage to the 3A fuses comes from the seat switch pack.
Seat switch pack
Each seat switch pack contains two switches representing the seat cushion and the seat squab. The switches provide the following adjustments:
- Seat fore/ aft.
- Cushion front up/ down.
- Cushion rear up/ down.
- Squab fore/ aft.
- Lumbar inflate.
- Lumbar deflate.
The voltage supply to the seat switch pack is from the 40A fuse in the satellite fuse box. A pair of switches controls the operation of each seat motor, the lumbar pump and the lumbar deflate relay.
Seat fore aft motor
The seat fore/ aft 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 fore/ aft 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 fore aft motor
The squab fore/ aft 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.in2). If a problem occurs with the lumbar bladder, e.g. a rupture, the whole lumbar system must be replaced. The components are not serviceable.
Power comes from the seat switch pack through a 3A fuse in the satellite fuse box. The lumbar pump and the lumbar deflate solenoid share an earth.
Lumbar deflate solenoid
The lumbar deflate solenoid vents the lumbar bladder to atmosphere to allow air to evacuate the bladder. The average time to evacuate the bladder with a load of 25 kg (55 lb) is 9 seconds.
Power comes from the seat switch pack through a 3A fuse in the satellite fuse box. The lumbar deflate solenoid and the lumbar pump share an earth.