Land Rover Discovery: Seating - Operation

FRONT SEAT ADJUSTMENT - NON-MEMORY SEATS

The driver and passenger seat switchpacks each receive a permanent fused primary battery power supply from the Central Junction Box (CJB). This feed is always live regardless of ignition power mode status.

Each switch provides a ground and power supply to the respective seat motor. When a particular function is required to operate in the opposite direction, the polarity to the motor is reversed via the respective switches.

A separate power supply is used for the lumbar assembly power supply.

Power for the lumbar assembly is from the primary battery via a fuse and seat relay in the Rear Junction Box (RJB).

In the event that a motor reaches the end of its functions travel, an internal thermal cut-out switch will trip to temporarily remove voltage from the motor.

FRONT SEAT ADJUSTMENT - MEMORY SEATS

On memory front seats, the driver or passenger seat module receives two permanent power supplies; one from the Central Junction Box (CJB) and one from the Rear Junction Box (RJB). The power supply from the CJB is used to operate the adjustment motors. The power supply from the RJB is used to operate the driver or passenger seat module.

A fused power supply is connected from the RJB via a seat relay to the seat switchpack and the seat module. Operation of a seat motor switch is converted to a Local interconnect Network (LIN) bus message within the switchpack, which is passed to the seat module. The seat module processes the LIN bus signal and operates the applicable seat motor as required. The seat lumbar assembly is operated with a power supply direct from the seat switchpack.

The driver and passenger seat modules are connected to the medium speed Controller Area Network (CAN) body systems bus. This allows the driver seat module to monitor the position of the door mirrors, using signals from the door modules and CJB respectively, when storing and recalling memory settings. The medium speed Controller Area Network (CAN) body systems bus connection also allows both the driver seat module and the driver door module to transmit memory information to enable confirmation chimes and message display in the Instrument Cluster (IC).

Stall Detection

A seat adjustment motor is deemed to have stalled if there is no change in the input from the feedback sensor of the motor for 200 ms. If a stall condition is detected then the drive to that motor is cancelled for the remainder of the memory recall operation or until the switch is re-selected (manual movement). The motor may be activated again, to move past the stall position, by pressing the appropriate switch for more than 2 seconds. If sensor feedback is detected, then the motor will continue to be driven until the switch is released. 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 pressed again, when a further 0.5 second of activation is permitted. This is known as inch mode, which allows seat adjustment to be maintained if sensor feedback is lost.

Initialization

When a replacement driver or passenger seat module is fitted, it must be calibrated using Land Rover approved diagnostic equipment so that the seat module can learn the positions of the seat adjustment motors.

Battery Monitor

If the primary battery voltage drops below 10.5 V, the driver seat module ignores all requests for a memory recall until the battery voltage has reached 11.5 V. This conserves as much battery power in the primary battery as possible to enable engine cranking.

FRONT DRIVER'S SEAT MEMORY

The seat memory switchpack has three hardwired connections to the driver door module. One wire provides a reference voltage to the memory switches, the second provides a ground and the third controls the memory LED status. Operation of the any of the memory switches is passed through resistors of varying resistance within the switchpack to the driver door module. The switch operation is detected by the driver door module and converted into a medium speed CAN body systems bus signal which is sent to the driver seat module to recall or store the memory positions.

Memory settings are stored in the driver seat module by pressing the memory switch and then, within 5 seconds, one of the memory switches 1-3.

When the memory switch is pressed the Light emitting Diode (LED) in the switch illuminates. After the memory switch 1-3 is pressed, the LED goes off and a chime sounds to confirm that the settings have been memorized. If the ignition is on (power mode 6), the message center will display a confirmation message. Any previously stored settings on the selected memory switch will be over-written.

Memory settings are recalled by pressing the applicable memory switch 1-3.

If the ignition is on (power mode 6), the message center will display a confirmation message.

FRONT SEAT HEATING

The front seat heater switches are integral to the Automatic Temperature Control Module (ATCM).

Operation of a seat heater switch is converted to Local Interconnect Network (LIN) bus signal by the Automatic Temperature Control Module (ATCM). The LIN bus signal is passed to the seat heater control module which is integral with the seat cushion heater element. The seat heater control module processes the LIN bus signal and outputs the required voltage to the seat heater elements to maintain the requested temperature.

Three levels of heating are selectable by sequential operation of the switch to select low, medium or high heat settings. The ATCM detects the switch operation and transmits the appropriate LIN bus signal to the seat heater control module.

REAR SEAT HEATING

The rear seat heater switches are located in the rear of the floor console.

Operation of a seat heater switch transmits a LIN bus signal from the switch to the ATCM which passes the LIN bus signal to the rear seat heater control module which is integral with the rear seat cushion heater element. The seat heater control module processes the LIN bus signal and outputs the required voltage to the seat heater elements to maintain the requested temperature.

Three levels of heating are selectable by sequential operation of the switch to select low, medium or high heat settings. The ATCM detects the switch operation and transmits the appropriate LIN bus signal to the rear seat heater control module.

FRONT SEAT CLIMATE

The front seat climate switches are integral to the Automatic Temperature Control Module (ATCM). Operation of a climate seat switch is detected by the ATCM which send a medium speed CAN comfort systems bus message to the Touch Screen to display the climate menu. Selections on the menu screen are passed back to the ATCM on the medium speed CAN comfort systems bus. The ATCM processes the CAN signals and outputs a LIN bus message to the applicable front seat climate control module. The front seat climate control module processes the LIN bus signals and operates the seat cushion and backrest climate assemblies as required to heat or cool the seat.

The seat climate control module uses the signals from temperature sensors in the backrest and the cushion climate assemblies to regulate the seat at the selected temperature. If full seat heating/cooling is selected, both the backrest and the cushion climate assemblies are activated. If partial seat heating/cooling is selected, only the backrest climate assembly is activated.

Climate seat operation will only operate when the engine is running (power mode 6). The power supply to the front seat climate control modules is controlled by an extended ignition relay in the Central Junction Box (CJB).

The thermal electrical device and the blower in the climate assemblies have a high power demand which is controlled by the CJB to preserve primary battery power.

FRONT SEAT LUMBAR (IF FITTED)

The lumbar switch is a two-way switch located in the seat switchpack.

A separate power supply is used for the lumbar assembly power supply.

Power for the lumbar assembly is from the primary battery via a fuse and seat relay in the Rear Junction Box (RJB). The relay is controlled by the CJB.

The CJB will de-energize the seat relay to preserve primary battery power if required.

The two-way lumbar switch controls both the lumbar air pump and the solenoid valve. When the switch is moved to the inflate position, power is supplied through the seat relay contacts to the air pump motor. The air pump motor will operate for as long as the switch is held in the 'inflate' position, or until the maximum pressure is achieved. When the switch is moved to the 'deflate' position, power is supplied to the solenoid valve which operates to open the valve to deflate the lumbar assembly air cell.

SECOND ROW SEAT ELECTRIC BACKREST RELEASE (IF FITTED)

Power is supplied to each seat backrest release motor via a relay the Quiescent Current Control Module (QCCM). The QCCM can remove power from non-essential systems if primary battery voltage becomes low.

The switch for each seat backrest release motor provides a ground path for the motor. When the ground is completed for more than 0.5 seconds and the operating criteria have been met, the motor operates, pulling the release cable. When the switch is released, the ground path is removed and the seat backrest return spring returns the cable and motor to its initial position.

Each seat backrest release motor is connected on a LIN bus to the Central Junction Box (CJB).

The LIN bus provides control by the CJB for the backrest release motor to make sure that the operating conditions are correct before releasing the backrest latch.

The following conditions must be met:

• The backrest release switch must operated for ore than 0.5 seconds
• Vehicle speed must be less than 5 km/h (3 mph)
• Tailgate must be open
• Ignition must be in powers modes 0, 4, 6 or 7.

Third Row SeatsSeating Seat Cover Inspection / Description and Operation

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