Discovery 2. Manual - part 752

WINDOWS

DESCRIPTION AND OPERATION

86-5-5

Front window switches

The front window switches are non-latching rocker switches located in the center console. The front window switches 
contain illumination bulbs that operate when the side lamps or headlamps are on.

The front window switches provide earth signals to the BCU.  The BCU determines which direction to operate the front 
window motors.

TestBook will monitor the real time status of the front window switches. 

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.