Thread: lower my disco

can give the wire colours if that helps

Thanks for that.

Now all I need to know is what is the trigger voltage?

if i run a voltmeter across the valve terminals and then hit the offroad mode to lift the car, will that tell you what you need ?

Now, that it would...

need both voltages. One for the raise, and the other for lower...

DESCRIPTION AND OPERATION
DISCOVERY 4.89
Self Levelling and Anti-Lock Braking System (SLABS)
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.
SLABS Description
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.
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.

DESCRIPTION AND OPERATION
4.90 DISCOVERY
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.
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.

DESCRIPTION AND OPERATION
DISCOVERY 4.91
SLS Operation
Air supply unit
Compressor
When compressor operation is required, the SLABS ECU supplies an output
feed from pin C0655-6 on a PN 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 C0881-1.
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.
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.

DESCRIPTION AND OPERATION
4.92 DISCOVERY
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.