Seats: Description and Operation
Seats
COMPONENT LOCATION
OVERVIEW
Two variants of driver and passenger seat are available:
^ Low line seat with 8-way adjustment finished in Blenheim leather
^ High line seat with 10-way adjustment finished in Oxford leather
The front seats are fitted with the seat belt bolted to the seat rail. The frames are common to both variants and are equipped with the following:
^ Seat control switches
^ Cushion front height adjustment
^ Cushion rear height adjustment
^ Cushion front tilt adjustment (high line only)
^ Backrest adjustment
^ Head restraint adjustment
^ Lumbar adjustment
^ Seat forward and rearward adjustment
^ Side air bag module
^ Backrest heating
^ Cushion heating
^ Seat climatic control (available as an option on the high line version)
WARNING: Prior to removal of the front seats and before disconnecting the front seat wiring harness electrical connectors (which includes the side air bag module electrical connectors), the battery ground cable should be disconnected and a period of at least 1 minute allowed to elapse. The same amount of care should be taken when handling and storing the front seats, as would be taken when handling and storing air bag modules.
Both variants of the front seats are fitted with a manually adjustable folding armrest on the inboard side of the seat. The memory recall functions are also available on higher specification vehicles.
The driver and passenger front seats, although almost identical, have some unique components. The front driver seat has a seat position sensor and the front passenger seat, for North American Specification (NAS) vehicles, has a seat occupant classification system, where as Rest Of the World (ROW) vehicles, except Australia, has a seat occupancy detection system. In both instances the components form an integral part of the Supplemental Restraint System (SRS).
The rear bench seats are designed to fold forward to increase the rear load space. a 60:40 split gives the owner increased flexibility when loading the vehicle with large objects. All rear seats are equipped with 3-point seat belts and adjustable head restraints. High line specification vehicles are also fitted with seat cushion heaters in both outboard seats.
Integrated Whiplash Reduction System
The integrated whiplash reduction system is incorporated into the backrest of the front seats. Head restraint forward positioning is activated by the natural occupant rearward displacement during low speed rear impacts. The head restraint forward positioning is achieved by 10.8 degrees maximum movement of an integral seat deployment paddle.
FRONT SEAT CONTROL SWITCHES
NOTE: Hi-line version shown, lo-line similar.
The switch pack is mounted on the seat valance of the driver and passenger seats and provides movement in the following axis:
^ Seat forward/rearward adjustment
^ Seat height adjustment
^ Seat angle adjustment
^ Backrest angle adjustment
^ Head restraint height adjustment (electric for hi-line and manual for lo-line)
Head Restraint Adjustment
Manual adjustment of the seat position can be carried out at any time, having priority over memory recall.
FRONT SEAT CONTROL COMPONENTS
Seat position is monitored by the seat module using seat track position Hall sensors incorporated into the motors. Seat memory is standard on the driver's seat. Each seat memory can be configured for 3 personality positions, which are set using the seat memory switch and stored in the driver seat module.
The switches for electrically adjusting the seats are located in the seat pack on the seat valance. The seat module is integral to the switch pack and controls the movement of the seat via hard-wired connections to the motors.
Seat Motors
The seat motors are permanent magnet motors. Two pins within the seat switch pack control the motors. Both pins are connected to ground. Operating a switch in one direction will apply voltage to that pin while the other pin remains connected to ground. Operating the switch in the opposite direction reverses power and ground to the motor allowing the motor to run in the opposite direction.
The seats can be manually adjusted at any time. Positioning is interrupted if manual adjustment is required during automatic adjustment (memory recall). The manual adjustment is not effective before the switch is operated again.
Due to the sequential activation of the drive motors, the switch requests are prioritised in the following order:
^ Forward/rearward adjustment
^ Backrest
^ Height
^ Angle
^ Head restraint
^ Backrest head
^ Steering column angle
^ Steering column forward/rearward adjustment.
HEATED SEATS
Front Seats
The seat heater elements are located in the seat cushion and backrest. The cushion and backrest heater elements are wired in series. The cushion heater element has an input feed from the temperature control unit and an output to the backrest heater element, which outputs to ground.
The seat heaters are thermostatically controlled and will operate intermittently to maintain a predetermined temperature. The indicators in the switches will remain illuminated until the heaters are either manually turned off, or the starter switch is turned off.
Feedback of the seat temperature is via a Negative Temperature Coefficient (NTC) sensor within the seat cushion. The resistance of this sensor changes with the temperature of the seat cushion allowing the Automatic Temperature Control (ATC) module to raise or lower the voltage to the seat heater elements to raise or lower their temperature.
An ignition feed is supplied to each sensor via the relevant seat heater switch.
CAUTION: The seat heaters consume considerable power from the battery. For this reason, they should only be operated while the engine is running.
Operation of the heated seats is controlled by the ATC module. Two push-button switches are mounted in the ATC module panel. Each switch has 2 integral Light Emitting Diodes (LED) to display the level of heating selected.
Climatic Seats
Seat Controls
High specification vehicles are fitted with climatic seats, which are able to deliver heating and cooling to the front seat occupants. Vehicles fitted with climatic seats feature 2 additional rotary controllers mounted in the instrument panel switch pack, adjacent to the clock. The rotary controllers are used to select cooling. Three levels of cooling and heating are available, dependant on the degree of switch rotation. The center of the switch is pressed once to ventilate both the seat back and cushion (both indicators on the switch will illuminate). A second press of the switch will ventilate the seat back rest only (the cushion indicator will extinguish).
NOTE:
^ If climatic seats are fitted, heated seat switches are not featured on the ATC module control panel.
^ The ATC module does not control any aspect of climatic seat operation.
The controlling software for the climatic seats is contained within a control module mounted below the driver's seat. When a temperature selection is made through either of the rotary controllers, the instrument panel switch pack provides a Pulse Width Modulation (PWM) signal to the control module. The control module interprets the PWM signal as a temperature value and attempts to heat or cool the seat accordingly.
Both climatic front seats contain two Peltier cells; one in the cushion, one in the backrest. The Peltier cells are able to deliver heating and cooling based on a voltage provided by the control module. Each seat also contains a fan, which blows air over the Peltier cells to distribute heating or cooling throughout the seat. The Peltier effect occurs when an electrical current is passed through a junction formed by two dissimilar conductors, creating a heat pump. A heat pump absorbs heat from one side of the system, causing it to cool, and then transfers the heat to the other side, causing it to warm. The cell is capable of cooling the incoming air by approximately 8 °C (12.4 °F), which means that temperature output will depend on the ambient temperature inside the vehicle.
The climatic seat control module monitors seat heating through a NTC temperature sensor. The temperature sensor is only used to monitor seat heating. Seat cooling is open loop, with no temperature signal provided back to the control module. When a temperature selection is made through either of the rotary controllers, the instrument panel switch pack provides a PWM signal to the climatic seat control module, which interprets the PWM signal as a temperature value and attempts to heat or cool the seat accordingly.
Although the switch LED's will illuminate if a selection is made when the ignition is switched on, the Peltier cells will not operate until the engine is running. After the ignition is switched off, the climatic seat control module will retain the current temperature settings for approximately 15 minutes. After this period, the seats will be set to 'off' when the ignition is switched back on.
Rear Seats
The rear seat heater elements are located in the outboard seat cushion and backrest. The cushion and backrest heater elements are wired in series. The cushion heater element has an input feed from the heater switch and an output to the backrest heater element, which outputs to ground.
The seat heaters are thermostatically controlled and will operate intermittently to maintain a predetermined temperature. The indicators in the switches will remain illuminated until the heaters are either manually turned off, or the starter switch is turned off.
Feedback of the seat temperature is via a NTC sensor within the seat cushion. The resistance of this sensor changes with the temperature of the seat cushion allowing the rear seat heater switch pack to raise or lower the voltage to the seat heater elements to raise or lower their temperature.
An ignition feed is supplied to each sensor via the relevant seat heater switch.
CAUTION: The seat heaters consume considerable power from the battery. For this reason, they should only be operated while the engine is running.
Operation of the heated seats is controlled by the ATC module. Two push-button switches are mounted at the rear of the floor console. Each switch has 2 integral Light Emitting Diodes (LED) to display the level of heating selected.
LUMBAR PUMP
The lumbar pump inflates a bladder in the backrest, 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.sq.in). The lumbar bladder can be replaced independently of the pump. The components are not serviceable.
MEMORY CONTROL MODULE
The memory control module, located within the driver switch pack, relies upon a number of inputs to control various outputs. As with all electronic control modules, the unit needs information regarding the current operating conditions of the engine and other related systems before it can make calculations, which determine the appropriate outputs.
The memory control module can store up to 3 different driver seating, mirror and steering column positions for each key.
All memory values are stored in the non-volatile memory, EEPROM. The current motor positions, which are monitored by the control modules integral Hall sensors, are stored in the EEPROM. If a loss of power occurs, upon power reconnection the current motor position are recalled from the memory and adopted as the current positions. This will allow the relative memory positions to be retained without any need to re-calibrate. The memory control module checks the integrity of all data stored in the EEPROM each time it exit's stand-by mode. In the event that the data is corrupt, the control module adopts the default values for all of the programming options. All memory positions are deemed as invalid and the software will perform as if there are no memory positions stored. Following the procedure for storing a memory position again will reset the relevant memory and allow full functionality.
Memory Function
Controlled by the memory module, the memory function stores and recalls the position of the driver's seat, the steering column and the exterior mirrors.
The memory recall functions are:
^ Forward/backward adjustment
^ Seat height
^ Seat angle
^ Backrest angle
^ External mirror adjustment
^ Steering column adjustment
Steering column adjustment The seat, steering column, and exterior mirrors will move to the stored position whenever the relevant memory-recall button in pressed.
NOTE: Seat, steering column and exterior mirror movement will be halted if any seat adjustment switch (including memory buttons) or the steering column adjustment switch is moved or pressed. To re-start movement of these, the relevant seat memory button will need to be pressed again.
Easy Entry/Exit
The 'Easy Entry/Exit' mode provides automatic movement of the steering column to allow easier entry to or exit from the vehicle.
NOTE: If the adjustment switch is moved during entry/exit operation, steering column movement will stop.
When the key is inserted in the ignition the steering column will return to their previous positions. If, however, the memorised driver position has been changed (using the seat memory switches or another key transmitter), the steering wheel and seat will move to the new position.
When the ignition key is removed, the steering column will move to the uppermost rake.
Stall Detection
Seat, steering column and mirror motors are deemed to have stalled if there is no change in the inputs that are received from the corresponding feedback sensors while that axis is being driven.
If a stall condition is detected then the drive to that axis is cancelled for the remainder of that memory operation (memory recall) or until the switch is re-selected (manual movement).
If the motor movement has stopped due to loss of sensor feedback, either, stall or sensor failure, then that axis may be activated again, to move past the stall position, by re-selecting the appropriate switch. This allows control of the motor to be maintained if sensor feedback is lost.
Upon re-selection of movement, if sensor pulses are detected then the motor will continue to be driven until the switch is released or another stall condition is detected. If sensor feedback is not detected then the motor is only driven for 0.5 second and then stops until the switch is released and then pressed again, when a further 0.5 second of activation is permitted, and so on.
For all seat motor and steering column manual movements, whenever a motor is driven and a stall occurs, the memory control module records the position at which the stall occurred. If movement occurs beyond a stall position, then that position is erased from the control modules memory. This will always allow movement past a previously recorded stall position once movement has been registered beyond that position. This is the case for both manual and memory movement.