Jaguar XJ (X350). Manual — part 1439

Item Part Number

Description

1

Seat backrest heaters

2

Seat squab heater pads

The heated seat system is available on all the seats except the standard rear seat option.

The heated seat system comprises of:

•

Heated seat switches

•

Backrest heater pad

•

Cushion heater pad and thermostat

•

FEM (front electronic module)

The FEM (front electronic module) controls the seat heating function by providing the
appropriate response depending on the status of the heated seat switches. The heated seat
functionality is constantly monitored by the electronic load management system (ELMS). The
ELMS dictates that in circumstances where the generated electrical power is less than the
electrical consumption, selected systems may be inhibited or operated using reduced power
for as long as is necessary.

With the ignition in the `ON` position, pressing a heated seat switch will select the maximum
heat setting for the chosen seat and is confirmed by three illuminated light emitting diodes
(LED) next to the switch. A second press selects the intermediate heat setting and two LEDs
are illuminated next to the switch. A third press selects the lowest heating setting, which is
displayed by one LED illuminating and a fourth press will deactivate the heated seat.

If the heated seat function has been activated, it will continue to operate until one of the
following conditions is met:

HEATED SEATS

•

A fixed period of time has expired (10 minutes)

•

The function is deactivated by pressing the heated seat switch for a fourth time

•

The ignition key is turned to the `ON` position

•

A malfunction is detected by the FEM (front electronic module) .

The heated seat function is designed to operate at temperatures below a predetermined limit
and the operation may be inhibited by a heated garage, body heat or warm ambient
temperatures.

CLIMATE SEATS

Item Part Number

Description

1

Seat back climate unit

2

Seat squab climate unit

On vehicles fitted with climatic seats, cooling as well as heating can be delivered to the front
seat occupants. Vehicles fitted with climatic seats feature 2 additional temperature switches
located in the instrument panel switch pack, above the touch screen display (TSD) for
operation of the front seats. The switches are momentary contact non latching switches that
increase and decrease the temperature for the individual seats. The switches provide a PWM
(pulse width modulation) signal to the control module.

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Item Part Number

Description

1

LH (left-hand) Seat cool button

2

LH (left-hand) Seat heat button

3

RH (right-hand) Seat cool button

4

RH (right-hand) Seat heat button

5

RH (right-hand) Temperature level indicator

6

LH (left-hand) Temperature level indicator

NOTE:

The seat heating and cooling buttons will operate as folows for each press; OFF
MAXIMUM, MEDIUM, MINIMUM OFF.

NOTE:

The ATC (automatic temperature control) module does not control any aspect of climatic
seat operation.

The controlling software for the climatic seats is contained within a control module mounted
behind the instument panel.

Each climatic seat contains 2 climate units. Each unit contains a fan, which blows air over
Peltier cells to distribute heating or cooling throughout the seat.

The climatic seat control module monitors seat heating through a NTC (negative temperature
coefficient) temperature sensor located in the unit. 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.

Although the switch LED (light emitting diode) will illuminate if a selection is made when the
ignition is switched on, the Peltier cells will not operate until the engine is running.

Item Part Number

Description

A

Normal position.

B

Weight forced into seat head restraint moves forward.

C

Weight fully forced into seat head restraint fully forward.

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 attached to pressure plate in the seat back. In a
collision from the rear, the occupant is pressed into the backrest, moving the pressure plate
towards the rear. As the seat occupant’s back and body weight presses against the pressure
plate 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. Precise activation of the system is
determined by the force with which the occupant's back is pressed against the backrest, the
magnitude of the collision, and the occupant's weight.

ACTIVE HEAD RESTRAINTS

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