Seats: Description and Operation
Seats
COMPONENT LOCATION
INTRODUCTION
Front Seat Sport Variant
Front Seat Luxury Variant
Rear Seats
Two variants of driver and passenger seat are available; 10-way sports and 16-way luxury. The front seat frames are common to both the coupe and convertible and are equipped with the following:
- Seat control switches (door mounted)
- Front seat cushion front height adjustment
- Front seat cushion rear height adjustment
- Front seat backrest adjustment
- Front seat head restraint adjustment
- Lumbar adjustment
- Front seat forward and backward adjustment
- Side air bag module
- Front seat backrest heating
- Front seat cushion heating
- Extendible seat-cushion (luxury variant only)
- Adjustable side bolsters (luxury variant only)
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.
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 has a occupancy sensing system. In both instances the components form an integral part of the air bag Supplemental Restraint System (SRS). For additional information, refer to Air Bag Supplemental Restraint System (SRS)
The rear seat squabs are conventionally trimmed over a wire frame with a removable center panel allowing access to the auxiliary junction box.
FRONT SEAT CONTROL SWITCHES
Sport Variant (10-way Adjustment)
Luxury Variant (16-way Adjustment)
The front seat control switches are installed in the driver and passenger door casings.
FRONT SEAT CONTROL COMPONENTS
Seat position is monitored by the individual seat modules using seat track position Hall sensors incorporated into the motors. This prevents the seat from being adjusted to a position that will contact the surrounding interior trim or a rear seat passenger causing injury (clash avoidance). Seat memory is standard on both drivers and passenger seats. Each seat memory can be configured for 3 personality positions, which are set using the seat memory switch and stored in the individual seat module.
The switches for electrically adjusting the seats are wired directly to the appropriate control module, which controls the movement of the seat via Local Interconnect Network (LIN) serial communication protocol.
NOTE:
In the event of a control module failure a fly lead behind the seat valance can be used to connect a power source directly to the seat slide motor. This enables the seat to be moved to gain access to the front and rear seat fixings. The seat can then be removed from the vehicle in order to access the control module.
As part of the Pre-Delivery Inspection (PDI) each seat needs to perform a clash avoidance check. This procedure is to ensure there is no contact between the seat trim and rear quarter casing. If there is any contact between the seat trim and rear quarter casing the affected seat must be recalibrated via the seat calibration routine in the Integrated Diagnostic System (IDS). For more information refer to the PDI manual.
FRONT SEAT HEATING
Operation of the heated seats is controlled by the Automatic Temperature Control (ATC) module. The ATC module receives a request from the Touch Screen Display (TSD) and sends a message to the Central Junction Box (CJB), which then provides a feed to the seat heater elements. For additional information, refer to Control Components Control Components
ACTIVE FRONT HEAD RESTRAINTS
Both front seats are fitted with mechanical active head restraints that reduce injuries to the spinal column and possible whiplash in the event of a rear collision. The 2 supports of the head restraints inside the seat backrest are joined together with fabric tape. As the seat occupant's back and body weight presses against the fabric tape the head restraint moves upwards and forwards mechanically by means of a pivot point. The movement of the headrest cushions the occupant's head, altering the posture and reducing the relative motion between the body and the head. The head restraint then returns to it's original position using a spring return mechanism.
PASSENGER SEAT OCCUPANCY SENSOR
Occupant monitoring provides the Restraints Control Module (RCM) with the occupancy status of the front passenger seat.
The occupant detection system determines if the front passenger seat is occupied or unoccupied. The system consists of a pressure sensor installed between the foam padding and the cover of the front passenger seat cushion. From the occupancy status, and the status of the front passenger safety belt, the instrument cluster determines the seat belt minder status. For additional information, refer to Air Bag Supplemental Restraint System (SRS)
FRONT SEAT BACK TILT
The front seats tilt forward to allow access to the rear seats. To tilt the seat forward remove the seat belt from the seat belt guide. Lift the lever and push the seat back forwards. The seat back will latch when returned to the normal position. Ensure that the seat belt is returned to the seat belt guide.
AUDIBLE AND VISUAL CONFIRMATIONS
A single chime audible confirmation is generated by the instrument cluster to provide confirmation to the driver that the memory store operation has been successfully completed.
In addition to audible confirmation there is also a visual confirmation via the instrument cluster message center. For additional information, refer to Instrument Cluster and Panel Illumination
STEERING COLUMN ADJUST
The instrument cluster controls the electric adjustable steering column in a rake (up and down) and reach (in and out). The steering column can be adjusted for rake and reach by operating the rotary joystick control switch on the LH side of the steering column.
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.
This mode is selected by setting the steering column adjustment switch to the 'AUTO' position.
If the 'Easy Entry Exit' feature fails to function, it can be activated as follows:
- Rotate the steering column adjust switch to the 'AUTO' position
- The instrument cluster will now display 'Column Adjust Auto' in the message center
For more information refer to the owners handbook.
Steering Column Control
Adjustment of the steering column is achieved by a single Direct Current (DC) motor. Each adjustment movement is transmitted through a solenoid actuated clutch; 1 clutch for reach movement and 1 for rake movement.
When engaged, a clutch can be released only if the system is unstressed. As the clutches are mounted on the same motor spindle, the sequence for position adjustment is as follows:
- Engage the selected clutch by powering the appropriate solenoid
- After a time period (approximately 0.1 of a second), the motor is powered in the desired direction. When the motor reaches the stop position the solenoid and motor is released/unpowered. The clutch remains engaged under stress
- At the start of the next adjustment the motor is powered in the opposite direction to enable the clutch to disengage when the stress is released.
Simultaneous rake and reach movements are not possible since the motor must reverse direction as soon as the first axis has reached its required position.
Steering column rake and reach is controlled via potentiometer feedback.
MEMORY CONTROL MODULE
The memory control module, located under the drivers and passengers seat, 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.
CONTROL DIAGRAMS
Driver Seat
NOTE:
A = Hardwired; N = CAN bus; O = LIN bus
Passenger Seat
NOTE:
A = Hardwired; N = CAN bus; O = LIN bus
PRINCIPLES OF OPERATION
Drivers Memory Seat
The memory control module can store up to 3 different driver seating, mirror and steering column positions. The numbered memory and single memory store switches control memory storage and recall operations. Each switch is a momentary action push switch.
Memory Store
Drivers Seat
Once the driver's seat, steering column and exterior mirrors have been adjusted, the vehicle is able to memorize these settings for future use by using the following procedure:
- Push the memory button M, the red Light Emitting Diode (LED) will illuminate for five seconds
- Whilst the LED is illuminated, press button 1, 2 or 3 to memorize the current settings
The LED will extinguish, and a chime will sound to confirm that the settings have been memorized. If the ignition is in the 'ON' mode, the message centre will display a confirmation message.
Passenger Seat
The procedure to memorize a passenger seat position is the same as that for the driver's seat with two exceptions. There will be no chime or message to confirm the settings.
Memory Recall
Memory recall has 3 memory positions stored for the seats, steering column and exterior mirrors. The switches for this function are located on driver and passenger door side trim panel. Pressing the appropriate numbered memory switch allows the seat to start moving to the position appropriate to that memory. When the switch is released the system will operate in manual mode. This means that when the switch is released, the seat will stop moving. In order to reach the intended memory position, the switch must not be released until all movement has stopped.
When a memory recall is initiated, to limit the overall current consumption, only 2-seat axis will move towards their intended position at any one time.
Both mirrors move simultaneously about the vertical axis first (left/right), and then, once all vertical axis movements are complete, about the horizontal axis (up/down). To minimize the number of mirror drives required, a method of sharing is implemented, which dictates that all movement about 1 axis is complete before movement about the other axis commences.
Immediate Adjustment
Pressing one of the manual adjustment switches will initiate the corresponding motor for that axis until the switch is released.
Only 2 seat motors can be driven at any one time.
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 for 200 ms (seat).
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 and pressing for longer than 2 seconds. 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, this is known as inch mode.
For all seat motor 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.
Initialization
When a replacement memory control module is fitted to a seat it should be calibrated via IDS diagnostic tester so that the control module can learn the seats absolute position.
Battery Monitor
If the battery voltage drops below 10.5 Volts, then the memory control module ignores all requests for a memory recall until the battery voltage has reached 11.5 Volts. This will conserve as much power in the vehicle battery as possible to enable engine cranking.
Stand-by Mode
The memory control module supports a stand-by mode to keep power consumption to a minimum.
If the control module is being prevented from entering stand-by mode due to motor movement, memory recall or switch operation, then it will enter stand-by mode when the current function has terminated.
NOTE:
In the case of a memory recall, all memory recall operations should be carried out before entering stand-by mode, not just the current motor movement.
The control module will exit stand-by mode if there is any CAN bus activity.
The exchange of information between the diagnostic unit and the memory control module is via the medium-speed CAN bus. There is a non-volatile Electronic Erasable Programmable Read Only Memory (EEPROM) for saving detected errors. Its contents are not lost when the power supply is disconnected. Only the IDS diagnostic tester can erase the error memory.