Seating: Other Land Rover Discovery IV

SEATS

Component Location

Note. RH drive shown, LH drive similar

MANUAL FRONT SEATS

POWER OPERATED FRONT SEATS (NON-MEMORY)

DRIVERS MEMORY SEAT

The memory control module can store up to three different driver seating, mirror and electric steering column (where fitted) positions for each key (up to 3 keys). The three-numbered memory and single memory store switches control memory storage and recall operations. Each switch is a momentary action push switch.

All seat adjustments are available whilst the ignition key is in position I or II or for a time period from when either the driver door status is changed or the ignition key status changes from position I to position 0 (key in).

Note. This does not include lazy entry where the door is not required to be open, or the ignition key is in position I or II.

The mirror adjustment is only enabled when the ignition key is in position I or II.

Memory Recall

Memory recall has three memory positions stored for the seats, exterior mirrors and electric steering column (where fitted). The switches for this function are located on driver's seat outer side trim panel. Pressing the appropriate numbered memory switch allows the seat to start moving to the position appropriate to that memory.

When a memory recall is initiated, to limit the overall current consumption, only two-seat axis will move towards their intended position at any one time. To minimise current load as the motors start, the initiation of each axis is phased with a 10ms delay between each motor starting.

The cushion slide and backrest will move first, followed by the cushion height and tilt. If the vehicle is stationary, the memory recall will operate in a 'one-touch' mode, whereby the switch can be released and the seat will continue to move to the memory position. If, however, the vehicle is in motion when the switch is released, then 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. The instrument cluster will emit a double chime to indicate that the recall operation has been successfully completed.

The following procedure will store a memory position

1. Ensure the ignition key is in position I or II
2. Ensure reverse gear is not engaged
3. Manually adjust the seat to the desired position, using the seat switches
4. Press and release the 'memory store' switch
5. Press and release the desired numbered memory switch within 5 seconds

With the ignition key in position II, a single chime will be emitted from the instrument cluster to indicate that the store operation has been successful.

If any of the seat adjustment or memory switches are activated during a 'one touch' memory recall, the recall will be overridden and the seat will begin to move in the direction corresponding to the switch that has been pressed.

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 minimise the number of mirror motor's required, a method of sharing is implemented, which dictates that all movement about one axis is complete before movement about the other axis commences.

Mirror movement coincides with the following table

Lazy Entry

Pressing the unlock button on the remote transmitter will initiate a memory recall. This feature is known as 'lazy entry'. If the seat movement, memory switch or the lock button on the remote transmitter is pressed, then the 'lazy entry' feature will stop immediately.

The memory settings are stored within Electronic Erasable Programmable Read Only Memory (EEPROM) of the memory control module each time the ignition switch is cycled from position II to position I. These are the positional values that a lazy entry request uses when the remote unlock button for that particular key is next pressed.

The lazy entry feature can be activated or deactivated via the customer personalization feature of the high line instrument cluster. This provides the driver with the option to enable or disable lazy entry as required. For additional information, refer to: INFORMATION AND MESSAGE CENTER .

REVERSE GEAR MIRROR POSITION

To give the driver a clear view of the curbs when reversing, the exterior door mirror's can be dipped when reverse gear is selected. The level of mirror dipping is set to a predetermined amount when the vehicle leaves the factory but has the ability to be customer programmed.

The following procedure will store a reverse gear mirror position

1. Ensure the ignition key is in position I or II
2. Perform a memory recall procedure
3. Ensure reverse gear is engaged
4. Manually adjust the mirrors to the desired position
5. Press and release the 'memory store' switch
6. Press and release the desired numbered memory switch
7. Reverse gear mirror dip setting will be stored for that particular memory setting.

A single chime will be emitted from the instrument cluster to indicate that the store operation has been successful and 'Mirror Dip Stored' message will be displayed in the message center.

Once this sequence has been completed, the stored mirror position will be the position that the mirrors move to when reverse gear is next selected.

Storing a memory position with reverse gear selected only affects reverse gear mirror positions, the remainder of the memory position's remain unchanged.

To protect against an accidental setting, the mirror position will only be stored if a mirror adjustment has been made since reverse gear was selected. If there is no reverse gear mirror position stored, then a default setting, stored in the memory control module, is adopted.

There are three customer personalization memory settings per key. For each of these settings there are 3 possible reverse gear mirror position stores. This equates to a possible nine reverse gear mirror position settings. Personalization memory setting relates to the 3 most recent ignition keys.

Scheme 55

The reverse gear mirror position feature can be activated or deactivated via the customer personalization feature of the high line instrument cluster. This provides the driver with the option to enable or disable reverse gear mirror position as required.

For additional information, refer to: Information And Message Center information.

Information regarding the reverse gear mirror status, for both manual and automatic transmissions, is transmitted as a message on the Local Interconnect Network (LIN) bus.

When the reverse gear mirror position feature is toggled 'OFF', all 3 memory settings associated with that personalization memory will return to the default reverse gear mirror settings.

Note. Reverse gear status is only available with the ignition in position II.

When reverse gear is de-selected, the mirror position immediately prior to reverse selection will be resumed, unless a memory recall has been requested whilst reverse has been selected, in which case the mirrors will move to the requested memory position when reverse is de-selected.

On vehicles fitted with the ZF automatic transmission there is a delay of 0.5 second following the selection of reverse gear, prior to the reverse mirror position being recalled. This is to prevent any movement of the mirrors as the gear selector is moved through the reverse position on the way to, and from, the park position.

Entry/Exit Mode

Entry/Exit mode provides automatic movement of the steering column and driver's seat to allow easier entry to or exit from the vehicle.

Entry/Exit mode is selected by setting the steering column adjustment switch to the 'AUTO' position.

Note. If the adjustment switch is moved away from 'AUTO' whilst the steering column is tilted away, the steering column will move back to it's memorized position when the key is next inserted in the ignition. Entry/Exit mode will then be cancelled. If the adjustment switch is moved during entry/exit operation, steering column movement will stop.

Exit

When the ignition key is removed, the steering column will move to the uppermost rake and innermost reach positions and the driver's seat will move slightly rearwards and lower.

Entry

When the key is inserted in the ignition the steering column and seat will return to their previous positions. If, however, the memorized 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.

Steering Column Control

Adjustment of the steering column is achieved by a single DC motor. Each adjustment movement is transmitted through a solenoid actuated clutch; one clutch for reach movement and one 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

1. Engage the selected clutch by powering the appropriate solenoid
2. After a time period (approximately 0.1 of a second), the motor is powered in the desired direction
3. When the motor reaches the stop position the solenoid and motor is released/unpowered. The clutch remains engaged under stress
4. After a time period (approximately 0.1 of a second), 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 it's required position.

Steering column rake and reach is controlled via potentiometer feedback.

AUDIBLE AND VISUAL CONFIRMATIONS

An audible confirmation is generated by the instrument cluster to provide confirmation to the driver that the requested operation has been successfully completed. The following operations support an audible confirmation

In addition to audible confirmation there is also a visual confirmation via the instrument cluster message center.

For additional information, refer to: Information And Message Center information.

MEMORY CONTROL MODULE

Memory Control Module Location (LHD Shown, RHD Similar)

The memory control module, located under the driver's seat, relies upon a number of inputs and controls a number of 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.

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 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. Memory store operations will reset the relevant memory and allow full functionality.

Stall Detection

Seat, steering column (where fitted) 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 200ms (seat), 1000ms (mirror & steering column) 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.

Initialization

When a replacement memory control module is fitted to a seat it should be initialized so that the control module can learn the seats and steering column maximum and minimum adjustment values. This is achieved by

1. Adjusting all seat movement axis from one end of travel to the other; slide, recline, height and tilt
2. Adjusting all steering column movement from one end of travel to the other; rake and reach.

Battery Monitor

If the battery voltage drops below 10.5 Volts, then the memory control module ignores all requests for a memory recall, including lazy entry, or easy entry/exit 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.

The control module will enter stand-by mode upon receipt of a LIN bus 'SLEEP' message from the Central Junction Box (CJB). Alternatively, a time period of 3 seconds after the LIN bus network has remained quiet provided there are no motors being driven at that time and there are no valid switch requests.

If there is a failure with the LIN bus network then the seat will be operational in 'inch mode' only.

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 LIN bus activity. When the control module exits stand-by mode it must verify the 'System Enable Status' in order to recognize when it should respond to a switch request.

Scheme 56

FRONT SEATS

Front Seat Heater Switches

Scheme 57

The heated front seat system is available on both manual and electric seats and is controlled by the Automatic Temperature Control Module (ATCM).

When the front seat heater switch is operated, power is supplied to the heater elements in the seat, causing the seat to heat up. The ATCM senses seat temperature via the sensor in the cushion and regulates voltage to the seat heater elements to maintain a constant temperature.

For additional information, refer to: Control Components information.

REAR SEAT HEATERS

Rear Seat Heater Switches

Note. Rear air conditioning variant shown

Scheme 58

The RH and LH rear seats support three integral heating elements, squab, back rest and bolster. The optional rear child booster seat also supports an integral seat-heating element.

Note. The rear center seat is not available with seat heating.

The rear seat heaters are enabled when the ignition switch is position II, and operate at one of two temperature settings. With the first press of a rear seat heater switch the relative rear seat heat control module (RH or LH) adopts the higher temperature setting, supplies a power feed to the related rear seat heater elements and illuminates two amber LED's in the switch. At the second press of the switch the control module adopts the lower temperature setting and extinguishes one of the LED's. At the third press of the switch the control module de-energizes the heater elements and extinguishes the second LED. The seat heaters remain on until selected off or the ignition is turned off.

The rear seat heat control modules receive an input from a temperature sensor in RH and LH rear seats, and regulate the power feed of the heater elements to control the seat temperature at the appropriate temperature setting between 35 and 45 °C (95 and 113 °F). The actual temperature settings vary with the type of seat covering, to allow for the different heat conduction properties of the different seat covering materials.

CONTROL DIAGRAM

Note. A = Hardwired; J = CAN bus