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

							DESCRIPTION AND OPERATION
4.60DISCOVERY SERIES II
EAT Operation
Gearbox solenoid valve block
The gearbox solenoid valve block is connected to the EAT ECU as follows:
zECU pin C0193-5 on an OG wire to gearbox solenoid pin C0543-H. This provides an 
output to the pressure regulator solenoid valve.
zECU pin C0193-43 on an R wire to connector interface C0728-2/C0678-2 and from the 
interface to the gearbox solenoid pin C0243-E on an OK wire. This receives a positive 
input from the gearbox output shaft speed sensor.
zECU pin C0193-14 on a B wire to connector interface C0728-1/C0678-1 and from the 
interface to gearbox solenoid pin C0243-F on an OB wire. This receives a negative 
input from the gearbox output shaft speed sensor.
zECU pin C0193-30 on an OP wire to gearbox solenoid pin C0243-B. This provides an 
output for the shift control solenoid valve (MV1).
zECU pin C0193-33 on an OW wire to gearbox solenoid pin C0243-K. This provides an 
output for the shift control solenoid valve (MV2).
zECU pin C0193-32 on an SO wire to gearbox solenoid pin C0243-M. This provides an 
output to the converter lock-up solenoid valve (MV3).
zECU pin C0193-53 on an OLG wire to gearbox solenoid pin C0243-L. This provides an 
output for power supply to the solenoid valves.
Starter/ inhibitor/ reverse light switch
The starter/ inhibitor/ reverse light switch is connected to the EAT ECU as follows:
zECU pin C0193-7 on a UG wire, via header C0724, to starter/ inhibitor/ reverse light 
switch pin C0675-37. This receives an input from the switch Y contacts. The input is 
also supplied via header C0724 to the BCU pin C0662-6.
zECU pin C0193-36 on a UP wire, via header C0724, to starter/ inhibitor/ reverse light 
switch pin C0675-9. This receives an input from the switch W contacts. The input is 
also supplied via header C0724 to the BCU pin C0662-9.
zECU pin C0193-8 on a UB wire, via header C0724, to starter/ inhibitor/ reverse light 
switch pin C0675-10. This receives an input from the switch X contacts. The input is 
also supplied via header C0724 to the BCU pin C0662-13.
zECU pin C0193-9 on a UW wire, via header C0724, to starter/ inhibitor/ reverse light 
switch pin C0675-6. This receives an input from the switch Z contacts. The input is also 
supplied via header C0724 to the BCU pin C0663-7.
The starter/ inhibitor/ reverse light switch pin C0675-4 is connected on a B wire, via splice 
SJ2, to earth header C0552.
The starter/ inhibitor/ reverse light switch pin C0675-1 is connected on a GN wire, via header 
C0287 LHD/C0294 RHD, to the BCU pin C0661-8. 
						

							DESCRIPTION AND OPERATION
DISCOVERY SERIES II 4.61
The starter/ inhibitor/ reverse light switch pin C0675-8 is connected on an NP wire to BCU 
pin C0663-10.
The starter/ inhibitor/ reverse light switch pin C0675-5 is connected on a BG wire, via splice 
joint A31 (and header C0294 LHD/C0287 RHD Td5 only), to BCU pin C0663-11.
On Td5 engine vehicles only, the starter/ inhibitor/ reverse light switch is connected from pin 
C0675-5, through splice joint A31, to connector interface C0681-10/C0668-10 on a BG wire. 
From the interface the connection continues on a BW wire, via header C0294 LHD/C0287 
RHD, to the ECM pin C0658-35.
Automatic transmission selector lamp
The automatic transmission selector lamp is connected to the BCU as follows:
zBCU pin C0662-22 on an RG wire to automatic transmission selector lamp pin C0245-
6.
zBCU pin C0662-23 on an RS wire to automatic transmission selector lamp pin C0245-
5.
zBCU pin C0662-24 on an RK wire to automatic transmission selector lamp pin C0245-
4.
zBCU pin C0662-25 on an RP wire to automatic transmission selector lamp pin C0245-
3.
zBCU pin C0662-26 on an RY wire to automatic transmission selector lamp pin C0245-
12.
zBCU pin C0662-8 on an RU wire to automatic transmission selector lamp pin C0245-
11.
zBCU pin C0662-9 on an RW wire to automatic transmission selector lamp pin C0245-
10.
The automatic transmission selector lamp pin C0245-9 is connected on a GLG wire to the 
IDM in the passenger compartment fusebox.
The automatic transmission selector lamp pin C0245-7 is connected on a UO wire to the 
EAT ECU pin C0193-45.
The automatic transmission selector lamp pin C0245-1 is connected on a B wire to earth 
header C0708. 
						

							DESCRIPTION AND OPERATION
4.62DISCOVERY SERIES II
Instrument pack
The instrument pack pin C0230-5 is connected on a YG wire to the EAT ECU pin C0193-51. 
This connection operates the manual mode lamp in the instrument pack.
The instrument pack pin C0230-4 is connected on a YR wire to the EAT ECU pin C0193-25. 
This connection operates the sport mode lamp in the instrument pack.
The instrument pack pin C0233-16 is connected on an SK wire, via header C0293 LHD/
C0292 RHD to the IDM in the passenger compartment fusebox. This connection is the serial 
data bus and supplies gear position data from the selector indicator, via the IDM, to the 
instrument pack.
Diagnostic socket
The diagnostic socket pin C0040-7 is connected on a K wire, via header C0286, to the EAT 
ECU pin C0193-31.
Engine Control Module (ECM)
The EAT ECU pin C0193-16 is connected on a W wire to ECM pin C0637-36 V8/C0158-35 
Td5.
The EAT ECU pin C0193-44 is connected on a Y wire to ECM pin C0637-37 V8/C0158-32 
Td5.
EAT ECU
EAT ECU pin C0193-13 is connected to the transmission high/low switch by an RK wire. 
When the transfer box is in low range the switch is closed and connects the RK wire to earth 
on a B wire through splice SJ2 and earth header C0552.
The EAT ECU is connected on B wires from pins C0193-6 and C0193-28 to earth header 
C0708. 
						

							DESCRIPTION AND OPERATION
DISCOVERY SERIES II 4.63
ACTIVE CORNERING ENHANCEMENT (ACE)
DESCRIPTION
General
The ACE system is an optional fitment to control vehicle roll angles. The system is 
electrically and hydraulically operated with all operations controlled by an ACE ECU. The 
ACE system provides improved vehicle handling and suspension characteristics and is 
active for both on and off-road driving. Refer to the Workshop Manual for detailed description 
and operation of the ACE system.
OPERATION
ACE Supply
Circuit supply
A feed from the battery positive terminal is connected on an R wire to the engine 
compartment fusebox. The feed passes through fusible link 8 and fuse 15.
The feed from fusible link 8 is connected on a NW wire to the passenger compartment 
fusebox and from the fusebox to the ignition switch on an N wire.
The feed from fuse 15 is connected to the contacts and coil of the ACE relay.
Ignition switch supply
When the ignition switch is in position II, the feed from fusible link 8 flows through the ignition 
switch to the passenger compartment fusebox on a Y wire and passes through fuses 25 and 
29.
Ignition signal
When the ignition is in position II, the feed from fuse 29 in the passenger compartment 
fusebox passes on a GO wire to the ACE ECU pin C0647-11.
ACE Operation
Mains supply
The coil of the ACE relay is connected to pin C0647-6 on a BR wire to the ACE ECU. When 
conditions are correct, the ACE ECU provides an earth path for the relay coil, which allows 
the feed from fuse 15 to energise the coil and close the relay contacts.
When the ACE relay contacts close, the feed from fuse 15 passes through the contacts and 
passes on a PO wire to pin C0647-28 on the ACE ECU. 
						

							DESCRIPTION AND OPERATION
4.64DISCOVERY SERIES II
Road speed signal
The ACE ECU receives a road speed signal from pin C0504-3, via header C0290, to ACE 
ECU pin C0647-5 on a KG wire.
ACE ECU
The ACE ECU receives two earth connections on B wires from pins C0647-20 and C0647-
32 to earth header C0018 LHD/C0017 RHD.
ACE upper accelerometer
The ACE ECU provides a power supply output on a YR wire from ECU pin C0647-18 to the 
upper accelerometer pin C0657-3.
The ACE ECU receives an earth input from the upper accelerometer pin C0657-2 to ECU 
pin C0647-34 on a YG wire.
The ACE ECU receives a signal input from the upper accelerometer pin C0657-1 to ECU pin 
C0647-17 on an OU wire.
ACE lower accelerometer
The ACE ECU provides a power supply output on a YB wire from ECU pin C0647-12 to the 
lower accelerometer pin C0656-3.
The ACE ECU receives an earth input from the lower accelerometer pin C0656-2 to ECU 
pin C0647-33 on a YK wire.
The ACE ECU receives a signal input from the lower accelerometer pin C0656-1 to ECU pin 
C0647-15 on an OS wire.
ACE valve block
The ACE valve block houses the pressure transducer, pressure control valve and two 
directional control valves. The ACE ECU sends and receives inputs and outputs to the valve 
block components as follows:
Pressure transducer
The ACE ECU provides a power supply output on a KY wire from ECU pin C0647-13 to the 
pressure transducer pin C0770-3.
The ACE ECU receives an earth input from the pressure transducer pin C0770-1 to ECU pin 
C0647-21 on a UG wire.
The ACE ECU receives a signal input from the pressure transducer pin C0729-2 to ECU pin 
C0647-16 on a KW wire. 
						

							DESCRIPTION AND OPERATION
DISCOVERY SERIES II 4.65
Pressure control valve
The ACE ECU provides a power output on a P wire from ECU pin C0647-27 to pressure 
control valve pin C0728-2.
The ACE ECU receives an earth input on a BG wire from ECU pin C0647-25 to the pressure 
control valve pin C0728-1
Directional control valves
The ACE ECU provides a power supply output on a GR wire from pin C0647-24 to the 
directional control valve 1 pin C0770-2 and directional control valve 2 pin C0771-2.
The ACE ECU receives an earth input from directional control valve 1 pin C0729-1 to ECU 
pin C0647-23 on an OG wire.
The ACE ECU receives an earth input from directional control valve 2 pin C0771-1 to ECU 
pin C0647-22 on a YB wire.
Instrument pack
The ACE ECU provides a warning lamp output to the instrument pack from ECU pin C0647-
36 to the instrument pack pin C0233-1 on a BO wire.
Engine speed signal
The ACE ECU receives an engine speed input signal from the ECM.
On V8 engine vehicles the signal is passed from ECM pin C0637-17 on a WS wire, via 
header C0291, to ACE ECU pin C0647-19.
On Td5 engine vehicles the signal is passed from ECM pin C0658-19 on a WS wire, via 
header C0291, to ACE ECU pin C0647-19.
Reverse gear signal
The feed from fuse 25 in the passenger compartment fusebox is connected to the reverse 
lamp switch (manual gearbox), or starter inhibitor/reverse light switch (automatic 
transmission), by a GY wire. When reverse gear is selected, the switch closes and the feed 
is connected to the ACE ECU, by a GN wire via header C0287 LHD/C0294 RHD, to provide 
a reverse gear selected signal. The reverse gear selected signal is used by the ACE ECU 
to set the system in a locked bars condition when reversing.
Diagnostic socket
The ACE ECU provides outputs and receives inputs from the diagnostic socket pin C0040-
7 on a K wire, via header C0286, to ACE ECU pin C0647-10. 
						

							DESCRIPTION AND OPERATION
4.66DISCOVERY SERIES II
SELF LEVELLING AND ANTI-LOCK BRAKING SYSTEM (SLABS)
DESCRIPTION
General
SLS and ABS is controlled by the Self Levelling and Anti-Lock Braking System (SLABS) 
ECU. The two systems are housed in the one ECU, but operate independently of each other.
The SLS system comprises an air supply unit comprising a compressor and air valves, two 
height sensors and the SLS part of the SLABS ECU. The SLS system controls the height of 
the rear suspension for off-road driving and passenger/load compensation. Refer to 
Workshop Manual - Description and Operation for further details.
The ABS system comprises ABS wheel sensors, an ABS modulator and the ABS part of the 
SLABS ECU. The ABS system also controls electronic brake distribution, hill descent 
control, centre differential lock control and electronic traction control. Refer to Workshop 
Manual - Description and Operation for further details.
NOTE: This Description and Operation applies to vehicles with Self Levelling Suspension 
(SLS). For vehicles without SLS refer to the ABS Description and Operation in this manual.
OPERATION
SLABS Supply
Circuit supply
A feed from the battery positive terminal is connected by an R wire to the engine 
compartment fusebox, where it passes through fusible links 8, 9 and 11 and fuse 11.
The feed from fusible link 11 is connected to the contacts of the ABS return pump relay in 
the engine compartment fusebox.
The feed from fusible link 9 is connected to the contacts of the SLS relay in the engine 
compartment fusebox.
The feed from fuse 11 is connected to the SLABS ECU pin C0504-1 on an NK wire.
The feed from fusible link 8 is connected to the passenger compartment fusebox on an NW 
wire and from the fusebox to the ignition switch on an N wire. 
						

							DESCRIPTION AND OPERATION
DISCOVERY SERIES II 4.67
Ignition switch supply
When the ignition switch is in position II, the feed from fusible link 8 flows through the ignition 
switch to the passenger compartment fusebox on a Y wire and passes through fuses 25, 27 
and 28.
From fuse 25 is connected to the contacts of the hill descent relay in the passenger 
compartment fusebox. The feed from fuse 25 is also connected on a GY wire to the reverse 
lamp switch (manual gearbox vehicles) or the starter inhibitor/reverse lamp switch 
(automatic gearbox vehicles). When the switch is operated, the feed is connected on a GN 
wire, through header joint C0287 LHD/C0294 RHD, to the SLABS ECU pin C0504-7.
From fuse 27 the feed is connected, via header C0760, on an LG wire to the hill descent 
switch. When the hill descent switch is operated, the feed continues from the switch on a PS 
wire to the SLABS ECU pin C0504-14.
From fuse 28 the feed is connected on an LG wire to the SLABS ECU pin C0504-2.
SLS Operation
Air supply unit
Compressor:
When compressor operation is required, the SLABS ECU supplies an output feed from pin 
C0655-6 on an NP wire to the engine compartment fusebox. The feed is connected to the 
coil of the SLS relay closing the relay contacts. The coil is connected from the fusebox on a 
B wire, via header C0286 LHD/ C0288 RHD to earth header C0018.
The feed from fusible link 9 passes through the relay contacts and is connected from the 
engine compartment fusebox on a WB wire to the SLS compressor. The compressor is 
connected on a B wire, via splice joint A47, to earth eyelet connector C0811-1.
SLS exhaust valve:
When exhaust valve operation is required, the SLABS ECU outputs a feed on pin C0655-5 
on a BW wire to the exhaust valve. The valve is connected on a B wire, via splice joint A47 
to earth eyelet connector C0811-1.
SLS LH rear valve:
When LH rear valve operation is required, the SLABS ECU outputs a feed on pin C0655-3 
on a WY wire to the valve. The valve is connected on a B wire, via splice joint A47 to earth 
eyelet connector C0811-1. 
						

							DESCRIPTION AND OPERATION
4.68DISCOVERY SERIES II
SLS RH rear valve:
When RH rear valve operation is required, the SLABS ECU outputs a feed on pin C0655-4 
on a UO wire to the valve. The valve is connected on a B wire, via splice joint A47 to earth 
eyelet connector C0811-1.
Off-road mode switch
When the non-latching off-road mode switch is pressed, an earth path is completed from 
SLABS ECU pin C0655-11 on a PK wire, via splice joint A186, to the off-road mode switch. 
The switch is connected on a B wire, via headers C0725 and C0760 to earth header C0017 
LHD/C0018 RHD.
The momentary completion of the earth path is sensed by the ECU which then operates the 
air supply unit accordingly. The ECU then connects pin C0655-11 to earth. The earth is also 
connected to the off-road mode warning lamp in the instrument pack on a PK wire from 
splice joint A186, causing the warning lamp to illuminate. The ECU quickly removes and re-
instates the earth path continuously to check if a second off-road mode switch request has 
been made.
Door switches
The SLABS ECU receives earth input signals from the door switches to inform the ECU that 
a door is open. The ECU can only differentiate between the drivers door on ECU pin C0655-
1 and the remaining doors on pin C0655-2.
Drivers door
The earth input for ECU pin C0655-1 is connected on a PW wire, via headers C0287 LHD/
C0285 RHD, to the front (drivers) door lock motor. The motor is connected on a B wire to 
earth header C0017 LHD/C0018 RHD.
Passenger door
The earth input for ECU pin C0655-2 is connected on a PLG wire to header C0291 LHD/
C0285 RHD. From the header a PLG wire is connected to connector interface C0464-1/
C0733-1. A PW wire connects the front (passenger) door lock motor to the connector 
interface. The motor is connected on a B wire to earth header C0018 LHD/C0017 RHD.
LH and RH rear doors
The earth input for ECU pin C0655-2 is connected on a PLG wire to header C0291 LHD/
C0285 RHD. From the header PLG wires connect to the LH and RH rear door lock motors. 
Each motor is connected on a B wire to earth header C0552. 
						

							DESCRIPTION AND OPERATION
DISCOVERY SERIES II 4.69
Tail door
The earth input for ECU pin C0655-2 is connected on a PLG wire to header C0291 LHD/
C0285 RHD. From the header a PLG wire connects to the tail door motor switch. The motor 
is connected on a B wire to earth header C0706.
Body Control Unit (BCU)
The SLABS ECU provides outputs and receives inputs to/from the BCU on connectors 
C0655 and C0504 as follows:
zAn output is passed from SLABS ECU pin C0655-7 to BCU pin C0660-10 on a WK 
wire. This output enables the SLS audible warning.
zAn input is received from BCU pin C0660-12 to SLABS ECU C0655-12 on a WU wire. 
This input is the SLS raise/lower command from the remote handset.
Instrument pack
The SLABS ECU provides an output from pin C0655-8 on a WO wire to the instrument pack 
pin C0233-2 for SLS warning lamp operation.
Height sensors
The SLABS ECU provides outputs and receives inputs from the left and right hand height 
sensors as follows:
LH height sensor
zPower supply output from SLABS ECU pin C0654-1 on an SY wire to LH height sensor 
pin C0764-5.
zEarth output from SLABS ECU pin C0654-2 on an SU wire to LH height sensor pin 
C0764-1.
zSignal input from LH height sensor pin C0764-4 on an SR wire to SLABS ECU pin 
C0654-3.
RH Height sensor
zPower supply output from SLABS ECU pin C0654-4 on an SG wire to RH height sensor 
pin C0763-5.
zEarth output from SLABS ECU pin C0654-5 on an SO wire to RH height sensor pin 
C0763-1.
zSignal input from RH height sensor pin C0763-4 on an SB wire to SLABS ECU pin 
C0654-6.
Engine Control Module (ECM)
The ECM provides an engine speed signal on a WS wire to header C0291. From the header 
the signal is passed on a WS wire to the instrument pack for tachometer operation. A second 
WS wire is connected from the header to the SLABS ECU pin C0655-10.
ABS Operation
Refer to Anti-lock Braking System (ABS) - Operation in this manual for description of the 
ABS circuit.