1999 LAND ROVER DISCOVERY window

WINDOWS
86-5-6 DESCRIPTION AND OPERATION
Front window motors
The front window motors are permanent magnet motors. There is a window motor in each front door. The front
window motors are controlled by the BCU.
The BCU provides both the voltage and the earth paths to the front window motors. The BCU reverses the direction
the window motor operates by switching the voltage and earth paths to the window motor. The BCU also monitors
stall current for the front window motors.
TestBook can operate the front window motors remotely.

WINDOWS
DESCRIPTION AND OPERATION 86-5-7
Rear window lift relay
The rear window lift relay is a normally open relay that provides power to the rear window system. It is controlled by
the IDM. The IDM receives a rear window enable signal from the BCU to allow operation during the ignition switched-
off timeout period.
Both the rear window lift relay and the IDM are located in the passenger compartment fusebox. The IDM is integral
to the passenger compartment fusebox.
The rear window lift relay receives voltage from fuse 13 (30A) in the passenger compartment fusebox. The IDM
controls the earth side of the relay coil.
TestBook cannot monitor the status of the rear window lift relay.

WINDOWS
86-5-8 DESCRIPTION AND OPERATION
Rear window switches
There are two sets of switches that operate the rear windows. There is a set of rear window switches located in the
centre console that allow the front seat occupants to operate the rear windows. The second set of switches are
located on the rear doors. All rear window switches are non-latching rocker switches.
A conventional window switch circuit controls the rear window system. In the rest position, there is battery voltage at
both sides of every switch as well as at the window motors. Operating any switch provides a ground path through the
switch to the window motor. Operating the switch in the opposite direction switches the voltage path and the earth
path to the motor allowing the motor to run in the opposite direction.
Voltage for the rear windows is from fuse 13 (30A) in the passenger compartment fusebox through the rear window
lift relay to the switches and motors.
TestBook cannot monitor the status of the rear window switches.

WINDOWS
DESCRIPTION AND OPERATION 86-5-9
Rear window isolation switch
The rear window isolation switch allows the front seat occupants to disable the rear window switches.
The rear window isolation switch is located in the centre console.
The rear window isolation switch is connected in the earth path in series with the rear door window switches.
Operating the rear window isolation switch interrupts the earth path to the rear door window switches, preventing the
rear door switches from operating the rear window motors. The rear windows can still be operated from the centre
console rear window switches.
TestBook cannot monitor the status of the rear window isolation switch.

WINDOWS
86-5-10 DESCRIPTION AND OPERATION
Rear window motors
There is a rear window motor located in each rear door. The rear window motors are permanent magnet motors with
an integral circuit breaker that provides stall protection.
The rear window switches provide battery voltage and an earth path to the rear window motors. Operating the switch
in the opposite direction reverses the voltage and earth paths at the rear window motor, allowing the motor to run in
the opposing direction.
TestBook cannot monitor the rear window lift motors.

WINDOWS
DESCRIPTION AND OPERATION 86-5-11
Operation
Front windows
In order for the windows to operate the ignition switch must either be in position II, or in the off position with the ignition
switched-off timeout operational.
The front window switches provide ground signals to the BCU, which operates the windows.
One-touch down operation
The front windows will open completely with a single touch on the window down switch.
In order for the one-touch down to operate, the following conditions must exist:
lIgnition switch in position II, or in the off position with the ignition switched-off time out operational.
lFront window switch pressed for less than 0.4 second.
When the front window down switch is pressed for less than 0.4 second, the window opens completely. Pressing the
window up switch for less than 0.2 second stops the movement of the window. The BCU stops one-touch down
operation when it detects window stall current or after 10 seconds of window operation.
Depending on market, one-touch down operation can be fitted on both front windows or on the driver's side only.
Rear windows
In order for the windows to operate the ignition switch must either be in position II, or in the off position with the ignition
switched-off timeout operational.
The rear windows operate by the switch providing both power and ground to the window motor. Pressing one side of
the switch provides a power and earth path to the window motor that allows the window motor to operate in one
direction. Pressing the other side of the switch reverses the power and earth, which allows the window motor to
operate in the opposite direction.

WINDOWS
REPAIRS 86-5-13
REPAIRS
Switch - rear door
$% 86.25.10
Remove
1.Remove screw securing escutcheon to door
casing.
2.Release escutcheon, far enough to access
switch multiplug, and disconnect multiplug
from switch.
3.Remove switch from escutcheon.
Refit
1.Connect new switch to multiplug and fit to
escutcheon.
2.Fit escutcheon to door casing and secure with
screw.
Switch - console
$% 86.25.19
Remove
1.Remove console switch cover.
2.Remove 4 screws securing switch mounting
plate to console.
3.Release mounting plate from console and
disconnect multiplug from switch.
4.Release and remove switch from mounting
plate.
Refit
1.Fit new switch to mounting plate and connect
multiplug.
2.Position mounting plate and secure with
screws.
3.Fit console switch cover.

WINDOWS
86-5-14 REPAIRS
Switch - heated rear screen
$% 86.65.36
Remove
1.Carefully remove switch.
2.Disconnect multiplug from switch.
3.Remove switch.
Refit
1.Connect multiplug switch.
2.Position switch and push to secure.