Land Rover Discovery 99my To 03my Electrical Library 3rd Edition Rover Manual

EARTH POINTS AND HEADER JOINTS
3.2DISCOVERY SERIES II 

DESCRIPTION AND OPERATION
DISCOVERY SERIES II 4.1
DE SCRIP TION AND OPERATIONANTI-THEFT ALARM
DESCRIPTION
Anti-Theft Alarm Description
The anti-theft alarm system is controlled by the Body Control Unit (BCU). The system alarms 
and disables the vehicle and monitors the vehicle status using door switches and ultrasonic 
sensors. The BCU also operates in conjunction with the Engine Control Module to disable 
the engine operation. Refer to the Workshop Manual for detailed Description and Operation 
of the...

DESCRIPTION AND OPERATION
4.2DISCOVERY SERIES II
Where an alarm sounder unit is installed, a feed from fuse 13 is connected on a PN wire from 
the engine compartment fusebox to the passenger compartment fusebox. The feed passes 
through a diode and is connected to the coil of a relay integrated into the fusebox. The relay 
controls a power feed to the alarm sounder unit. Activation of the relay is controlled by the 
BCU via the IDM. The BCU communicates with the IDM using serial data messages on a 
SK...

DESCRIPTION AND OPERATION
DISCOVERY SERIES II 4.3
Vehicle horns
The contacts of the horn relay, in the engine compartment fusebox, are connected to the LH 
and RH horns by PG wires. The LH horn is earthed by a B wire connected to earth point 
C0564. The RH horn is earthed by a B wire connected to earth header C0018. Where the 
vehicle horns are used by the anti-theft alarm system, the horn relay coil is connected to the 
BCU, via header C0286, by a PO wire. To operate the horns the BCU earths the PO...

DESCRIPTION AND OPERATION
4.4DISCOVERY SERIES II
Key in sensor
A feed from fuse 20 in the passenger compartment fusebox is connected on a P wire to 
header C0289 LHD/C0294 RHD. From the header the feed is connected on a P wire to the 
key in sensor.
When the ignition key is inserted into the lock barrel the key in sensor contacts close. The 
feed passes through the sensor and is connected on a WP wire, via header C0293 LHD/
C0289 RHD, to pin C0662-2 on the BCU.
A second connection from the key in sensor...

DESCRIPTION AND OPERATION
DISCOVERY SERIES II 4.5
LH front door lock motor (LHD vehicles only)
The LH front door lock motor switch is connected on a UG wire to pin C0660-5 on the BCU 
and on a US wire to pin C0661-22 on the BCU.
The LH door switch is connected on a PW wire, via header C0287, to pin C0660-17 on the 
BCU.
The LH front door lock motor is connected on a B wire, via header C0288, to earth header 
C0017.
RH front door lock motor (RHD vehicles only)
The RH front door lock motor switch is...

DESCRIPTION AND OPERATION
4.6DISCOVERY SERIES II
RH rear door lock motor (RHD vehicles only)
The RH rear door switch is connected on a PLG wire to pin C0660-4 on the BCU via header 
C0285. The RH rear door switch is also connected on a B wire to earth header C0552.
LH rear door lock motor (LHD vehicles only)
The LH rear door switch is connected on a PLG wire to connector C0805-3/C0753-3 
interface. From the connector interface the wire continues on a PLG wire to header C0291 
and from the header to pin...

DESCRIPTION AND OPERATION
DISCOVERY SERIES II 4.7
CENTRAL DOOR LOCKING (CDL)
DESCRIPTION
General
Four methods are available for locking the doors; locking using vehicle key, remote handset 
locking, locking using the CDL switch on the fascia or speed related locking. The anti-theft 
alarm operates in conjunction with the CDL system. Refer to Anti-Theft Alarm - Description 
and Operation in this manual for alarm details.
Two levels of door locking are available; Central Door Locking (CDL) and...

DESCRIPTION AND OPERATION
4.8DISCOVERY SERIES II
OPERATION
CDL Supply
Circuit supply
A feed from the battery positive terminal is connected by an R wire to the engine 
compartment fusebox, where it passes to fusible link 3 and fuse 13.
The feed from fusible link 3 is connected on an NR wire to the passenger compartment 
fusebox where it passes through fuses 1, 20 and 21.
From fuse 1 in the passenger compartment fusebox the feed is connected to the contacts of 
the four electronic CDL relays in the...

DESCRIPTION AND OPERATION
DISCOVERY SERIES II 4.9
The BCU receives the road speed signal from the instrument pack via the serial data bus to 
BCU pin C0661-1. The BCU uses the speed signal to enable the speed related locking when 
the road speed exceeds 4 mph (7 km/h).
The BCU is connected on a B wire from pin C0660-11 to earth header C0551.
The BCU is connected on a US wire from pin C0660-22 to the driver’s door lock motor 
switch. This connection provides an earth signal which informs the BCU that CDL...