2002 LAND ROVER DISCOVERY earth

SEATS
DESCRIPTION AND OPERATION 76-5-7
Operation - electric seats
Seat power relay enable line
The BCU provides the seat power relays with an earth supply to the relay coil that enables the relay operation. When
this seat power relay enable line is active, the seat power relay energises allowing seat operation.
In order for the seat power relay to be active the BCU must detect either of the following condition options:
lIgnition switch in position II.
lIgnition switch in position II or driver's door within 45 seconds of opening.
Seat fore/ aft movement
When the cushion switch is operated and the seat power relay enable line is operating, power and earth are supplied
to the motor in the seat, allowing the seat to move forward or backward depending on switch position. The motor
drives a gear wheel along a gear rack connected to the seat base. Sliding the cushion switch forward causes the motor
to drive the seat forward. Sliding the cushion switch rearward reverses polarity of the voltage at the seat motor, driving
the seat rearward.
Seat cushion front up/ down movement
When the cushion switch is operated and the seat power relay enable line is operating, power and earth are supplied
to the motor in the seat, allowing the front of the seat cushion to move upward or downward depending on switch
position. The motor drives a gear wheel along a gear rack connected to the seat base. Sliding the front of the cushion
switch upward causes the motor to drive the seat upward. Sliding the front of the cushion switch downward reverses
polarity of the voltage at the seat motor driving the seat downward.
Seat cushion rear up/ down movement
When the cushion switch is operated and the seat power relay enable line is operating, power and earth are supplied
to the motor in the seat, allowing the seat to move upwards or downwards depending on switch position. The motor
drives a gear wheel along a gear rack connected to the seat base. Sliding the rear of the cushion switch upward
causes the motor to drive the seat upward. Sliding the rear of the cushion switch downward reverses polarity of the
voltage at the seat motor driving the seat downward.
Squab fore/ aft movement
When the squab switch is operated and the seat power relay enable line is operating, power and earth is supplied to
the motor in the squab, allowing the squab to move forward or backward depending on switch position. The motor
drives a gear wheel along a rotary gear rack connected to the squab. Sliding the squab switch forward causes the
motor to drive the squab forward. Sliding the squab switch rearward reverses polarity of the voltage at the seat motor
driving the squab rearward.
Lumbar inflate/ deflate
Sliding the squab switch upwards when the seat power relay enable line is operating applies voltage to the lumbar
pump. The lumbar pump inflates the lumbar bladder, increasing lumbar support. The lumbar pump and the normally
closed lumbar deflate solenoid hold the air in the bladder. Sliding the squab switch downwards applies voltage to the
deflate solenoid, venting the air in the lumbar bladder to atmosphere, decreasing lumbar support.
Diagnostics
TestBook can only verify that the seat power relay line is enabled. It cannot determine the status of the system or any
of the components.

SEATS
DESCRIPTION AND OPERATION 76-5-11
Description - heated seats
Heated seats
The heated seat system is available on both manual seats and electric seats. The electrical sub-system consists of
the following components:
lSeat heater switches.
lSeat heater elements.
lTemperature control unit (if electric seats are fitted).
lTemperature sensor (if electric seats are fitted).
lThermostat (if manual seats are fitted).
Seat heater switches
The seat heater switches supply an ignition feed to either the temperature control unit (vehicles with electric seats) or
directly to the seat heater elements (vehicles with manual seats). When a seat heater switch is operated, current flows
to the seat heater elements causing them to heat the seat.
The ignition feed comes from fuse 15 in the passenger compartment fuse box.
Seat heater elements
The seat heater elements are located in the seat cushion and squab. The cushion and squab heater elements are
wired in series. Total power consumption at 13.5 volts is approximately 115 Watts.
The cushion heater element has an input feed from the temperature control unit or heater switch and an output to the
squab heater element, which outputs to earth.

SEATS
76-5-12 DESCRIPTION AND OPERATION
Temperature control unit
The temperature control unit is only fitted to vehicles with electric seats. Feed back of the seat temperature is via a
Negative Temperature Coefficient (NTC) sensor within the seat cushion. Resistance of this sensor changes with the
temperature of the seat cushion allowing the temperature control unit to lower or raise the voltage to the seat heater
elements to raise or lower their temperature.
An ignition feed is supplied via the seat heater switch. The temperature sensor supplies an input. Output is a supply
to the cushion heater element and an earth.
Thermostat
On vehicles with non electric seats, the temperature is controlled by a thermostat located in the seat cushion. The
thermostat interrupts the power supply when it reaches a pre-determined temperature.

SEATS
REPAIRS 76-5-15
REPAIRS
Seat - front
$% 78.10.43.99
Remove
1.Disconnect battery earth lead.
2.Remove 3 screws and 1 trim clip securing
lower trim casing to seat.
3.Remove lower trim casing.
4.Remove cap from front seat belt lower
anchorage bolt.
5.Remove front seat belt lower anchorage bolt. 6.Remove 4 Torx bolts and nut securing front
seat to floor.
7.Lean seat forward to gain access to multiplugs.

SEATS
76-5-16 REPAIRS
8.Release pretensioner multiplug from seat
frame and disconnect.
9. Electrically operated seats: Disconnect 2
seat motor multiplugs.
10.Remove front seat.
Refit
1.Fit front seat in vehicle.
2. Electrically operated seats: Connect seat
motor multiplugs.
3.Connect pretensioner multiplug and secure to
seat frame.
4.Fit Torx bolts and nut securing front seat to floor
and tighten to 45 Nm (33 lbf.ft).
5.Fit front seat belt lower anchorage bolt to front
seat and tighten to 32 Nm (24 lbf.ft).
6.Fit cap to lower anchorage bolt.
7.Fit lower trim casing to seat and secure with
screws and trim clip.
8.Connect battery earth lead.
Seat - third row
$% 78.10.45
Remove
1.Manufacture a spring retainer bracket to the
dimensions given above.
2.Position third row seat in deployed position.
3.Remove the cup holder (where applicable).

SUNROOF
DESCRIPTION AND OPERATION 76-6-5
Description
General
The sunroof system consists of a front and a rear sunroof assembly. Both sunroof assemblies slide and tilt to open.
The sunroof system consists of the following components:
lSunroof ECU.
lBCU.
lFront sunroof switch.
lFront sunroof motor and microswitch.
lRear sunroof - front switch.
lRear sunroof - rear switch.
lRear sunroof isolation switch.
lRear sunroof motor and microswitch.
The BCU enables operation of the sunroof ECU. If the sunroof ECU does not receive an enable signal from the BCU,
neither sunroof assembly operates. The BCU is located behind the glovebox. The sunroof ECU is located above the
headlining next to the front sunroof assembly.
TestBook diagnoses the sunroof ECU.
Front sunroof switch
The front sunroof switch is located in the roof console above the windscreen in front of the front sunroof. It controls
the front sunroof motor via the sunroof ECU.
The front sunroof switch supplies an earth signal to the sunroof ECU. The pin at the ECU that receives the earth
signal determines whether ECU causes the sunroof to open or close.
TestBook cannot monitor the state of the front sunroof switch.
The following table lists the values which can be measured at the listed ECU pins when the conditions outlined are
met:
Signal values (connector connected)
Connector/Pin
No.Condition Resistance, ohms
C0784-2 Ignition in position II, front sunroof switch released > 10,000
C0784-2 Ignition in position II, front sunroof switch open < 0.5
C0785-7 Ignition in position II, front sunroof switch released > 10,000
C0785-7 Ignition in position II, front sunroof switch closed < 0.5

SUNROOF
76-6-6 DESCRIPTION AND OPERATION
Front sunroof motor and microswitch
The front sunroof motor is located within the front sunroof assembly. The sunroof ECU controls the front sunroof
motor.
The sunroof ECU determines the direction the sunroof motor runs. A battery signal to one side of the motor and an
earth to the other side of the motor causes the motor to turn in one direction, reversing the polarity through the same
pins causes the motor to turn in the opposite direction.
The following table lists the values which can be measured at the listed ECU pins when the conditions outlined are
met:
Signal values (connector connected)
Connector/Pin
No.Condition Voltage Resistance, ohms
C0785-5 Ignition in position II, rear of front sunroof switch
pressed+voltage to C0785-
5
C0785-1 Ignition in position II, front of front sunroof switch
pressed+voltage to C0785-
1< 0.5
C0784-8 Ignition in position II, sunroof fully closed +V Batt
C0784-8 Ignition in position II, sunroof not closed > 10,0000

SUNROOF
DESCRIPTION AND OPERATION 76-6-7
Rear sunroof - front switch
The rear sunroof front switch is located in the roof console above the windscreen in front of the front sunroof. It
controls the rear sunroof motor via the sunroof ECU.
The rear sunroof front switch supplies an earth signal to the sunroof ECU. The pin at the ECU that receives the earth
signal determines whether ECU causes the sunroof to open or close.
TestBook cannot monitor the state of the rear sunroof front switch.
The following table lists the values which can be measured at the listed ECU pins when the conditions outlined are
met:
Signal values (connector connected)
Connector/Pin
No.Condition Ohms
C0784-7 Ignition in position II, rear sunroof front switch released > 10,000
C0784-7 Ignition in position II, rear sunroof front switch open < 0.5
C0785-8 Ignition in position II, rear sunroof front switch released > 10,000
C0785-8 Ignition in position II, rear sunroof front switch closed < 0.5