1999 LAND ROVER DISCOVERY ECU

BRAKES
DESCRIPTION AND OPERATION 70-23
Typical disabled times
Diagnostics
While the ignition is on, the diagnostics function of the SLABS ECU monitors the system for faults. In addition, the
return pump is tested by pulsing it briefly immediately after the engine starts provided vehicle speed exceeded 4.4
mph (7 km/h) during the previous ignition cycle. If a fault exists in a warning lamp circuit, the lamp will not illuminate
during the lamp check at ignition on but, provided there are no other faults, the related function will otherwise be fully
operational. If a fault is detected during the power up, the SLABS ECU stores a related fault code in memory and
illuminates the appropriate fault warning lamps. If a fault is detected later in the drive cycle, the SLABS ECU also
sounds the audible warning three times.
Fault codes and diagnostic routines can be accessed by connecting Testbook to the vehicle's diagnostic connector
in the driver's footwell.
Warning lamp fault operation
After detecting a fault, the SLABS ECU selects an appropriate default strategy which, where possible, retains some
operational capability. A shuttle valve switch fault and throttle position signal fault are classified as permanent faults.
If a permanent fault is detected, the related warning lamp illumination and default strategies are automatically
employed in subsequent ignition cycles, even if the fault is intermittent, until the fault has been rectified and cleared
from memory. If a non permanent fault is detected, the related warning lamp illumination and default strategies will
only be employed in subsequent ignition cycles if the fault is still present.
After rectification of an ABS sensor fault, the ABS and ETC functions are disabled, and the ABS warning lamp remains
illuminated after the lamp check, until vehicle speed exceeds 9.4 mph (15 km/h) (to allow additional checks to be
performed).
Vehicle speed, mph (km/h) Time, minutes
1.3 (2) 40
12.5 (20) 33
15.6 (25) 17
25.0 (40) 9
31.3 (50) 6
Item Check Warning lamp
ABS Brake ETC HDC
fault
ABS sensors Resistance (to check status) On On On On
Brake lamps relay Open/Short circuit Off Off Off On
Engine data Sticking throttle, signal failure, data corruption Off Off On On
Inlet solenoid valves Open/Short circuit On On On On
Outlet solenoid valves Open/Short circuit On On On On
Reference earth Connection to earth On On On On
Return pump monitor Correct pump operation On On On On
Return pump relay Open/Short circuit On On On On
Shuttle valve switches Open/Short circuit On On On On
SLABS ECU Internal failure On On On On
Supply voltages Range (10 to 16 V) On On On On

BRAKES
70-24 DESCRIPTION AND OPERATION
Default strategies
Electrical data
Nominal resistance values for applicable brake control components are as detailed below:
Fault Default strategy
Brake lamps relay ABS: Enabled.
ETC: Enabled.
EBD: Enabled.
HDC: Enabled.
Throttle position signal failure ABS: Enabled.
ETC: Disabled.
EBD: Enabled.
HDC: Immediately disabled if not in active braking mode; faded out then disabled if in active
braking mode.
No reference earth ABS: Disabled.
ETC: Disabled.
EBD: Partly disabled.
HDC: Disabled.
Return pump or relay fault ABS: Disabled.
ETC: Disabled.
EBD: Partly disabled.
HDC: Disabled.
Shuttle valve switch failure ABS: Deceleration threshold increased; return pump activated if sum of output valve
actuation on one axle exceeds 140 milliseconds.
ETC: Disabled.
EBD: Inlet valves of rear axle close at vehicle deceleration rates of 0.3 g and above.
HDC: Disabled.
SLABS ECU internal failure ABS: Disabled.
ETC: Disabled.
EBD: Disabled.
HDC: Disabled.
Supply voltage out of limits ABS: Disabled.
ETC: Disabled.
EBD: Disabled.
HDC: Disabled.
Component Resistance, ohms
Brake lamp relay coil117 - 143
Return pump relay coil82.8 - 101.2
ABS sensor950 - 1100
Shuttle valve switches, both open (brakes off) 2977 - 3067
Shuttle valve switches, both closed (brakes on) 1007 - 1037
Shuttle valve switches, one open, one closed 1992 - 2052
Inlet solenoid valve5.9 - 7.3
Outlet solenoid valve3.0 - 3.6

BRAKES
70-26 DESCRIPTION AND OPERATION
Description
General
The handbrake consists of a drum brake, installed on the rear of the transfer box, operated by a cable connected to
a handbrake lever between the front seats.
Handbrake lever
The handbrake lever is mounted on a base plate which attaches to the transmission tunnel. A conventional ratchet
and thumb operated release button are incorporated for locking and unlocking the lever. A warning switch on the base
of the lever operates the brake warning lamp in the instrument pack. While the handbrake is applied the warning
switch connects an earth to the instrument pack which, if the ignition is on, illuminates the brake warning lamp. In
some markets, the instrument pack performs a bulb check of the brake warning lamp each time the ignition is switched
on.
Cable
The handbrake cable consists of inner and outer cables installed between the handbrake lever and the drum brake.
A protective sleeve is installed on the cable to protect the cable from heat from the exhaust system. Handbrake
adjustment is provided by a threaded sleeve installed on the outer cable where it locates in the handbrake lever.
Turning an adjuster wheel, which is keyed to the threaded sleeve and secured by a 'C' clip, alters the effective length
of the outer sleeve and consequently changes the handbrake lever movement needed to apply the drum brake.

BRAKES
DESCRIPTION AND OPERATION 70-27
Drum brake
1Drum
2Drum securing bolt
3Backplate4Cable
5Backplate securing bolt
The drum brake consists of a backplate attached to the transfer box casing and a drum attached to the transfer box
rear output shaft. When the handbrake lever is applied, the movement is transmitted by the inner cable to a lever on
one of the brake shoes on the backplate. The lever pivots against the brake adjuster rod, which forces the shoes apart
and into contact with the drum. Brake shoe to drum clearance is set by an adjusting bolt on the rear of the backplate.

BRAKES
ADJUSTMENTS 70-29
ADJUST ME NTS
Handbrake
$% 70.45.09
Check
1.Apply the handbrake lever 3 notches on the
ratchet. The handbrake should be fully
operational.
2.If the handbrake is not fully operational, the
brake shoes and/or the handbrake cable need
adjusting.
Adjust
1.Raise rear of vehicle.
WARNING: Do not work on or under a
vehicle supported only by a jack. Always
support the vehicle on safety stands.
2.Ensure handbrake lever is fully released.
3.Tighten brake shoe adjusting bolt until brake
drum is locked, then back off adjusting bolt 1.5
turns. Check that the brake drum is free to
rotate.
4.Recheck handbrake operation.If handbrake is
not fully applied with 3 notches on the
ratchet, the handbrake cable requires
adjustment.
5.Remove switch panel from centre console.

+ WINDOWS, REPAIRS, Switch -
console.
6.Release handbrake lever gaiter from centre
console.7.Rotate adjuster anti-clockwise to increase
cable tension (reduce notches) or clockwise to
decrease cable tension (increase notches).
8.Recheck handbrake operation.
9.Secure handbrake lever gaiter to centre
console.
10.Fit switch panel to centre console.

+ WINDOWS, REPAIRS, Switch -
console.
11.Remove stand(s) and lower vehicle.

BRAKES
REPAIRS 70-33
REPAIRS
Brake disc - front
$% 70.12.10
Brake discs must be renewed in pairs, unless
one disc requires changing before 1000 miles
(1500 km) from new.
Remove
1.Raise front of vehicle.
WARNING: Do not work on or under a
vehicle supported only by a jack. Always
support the vehicle on safety stands.
2.Remove road wheel(s).
3.Remove 2 bolts securing brake caliper to
swivel hub.
4.Release caliper and tie aside clear of brake
disc.
CAUTION: Do not allow caliper to hang on
brake hose.
5.Remove screw securing disc to drive flange.
6.Remove brake disc from drive flange Refit
1.Clean mating faces of drive flange and new
disc.
2.Fit brake disc to drive flange, fit screw and
tighten to 13 Nm (10 lbf.ft).
3.Clean mating faces of caliper and hub.
4.Fit caliper, and tighten bolts to 175 Nm (129
lbf.ft).
5.Fit road wheel(s) and tighten nuts to 140 Nm
(103 lbf.ft).
6.Remove stand(s) and lower vehicle.

BRAKES
70-34 REPAIRS
Brake disc - rear
$% 70.12.33
Brake discs must be renewed in pairs, unless
one disc requires changing before 1000 miles
(1500 km) from new.
Remove
1.Raise rear of vehicle.
WARNING: Do not work on or under a
vehicle supported only by a jack. Always
support the vehicle on safety stands.
2.Remove road wheel(s).
3.Remove 2 bolts securing brake caliper to rear
hub.
4.Release caliper and tie aside clear of brake
disc.
CAUTION: Do not allow caliper to hang on
brake hose.
5.Remove screw securing disc to drive flange.
6.Remove brake disc from drive flange. Refit
1.Clean mating faces of drive flange and new
disc.
2.Fit brake disc to drive flange, fit screw and
tighten to 13 Nm (10 lbf.ft).
3.Clean mating faces of caliper and hub.
4.Fit caliper and tighten bolts to 95 Nm (70 lbf.ft).
5.Fit road wheel(s) and tighten nuts to 140 Nm
(103 lbf.ft).
6.Remove stand(s) and lower vehicle.

BRAKES
REPAIRS 70-35
Master cylinder - brake
$% 70.30.08
Remove
1.Disconnect multiplug from fluid level switch.
2.Position cloth under master cylinder to absorb
spilled fluid.
CAUTION: Brake fluid will damage paint
finished surfaces. If spilled, immediately
remove fluid and clean area with water.
3.Disconnect secondary system pipe union from
master cylinder.
4.Disconnect primary system pipe union from
master cylinder.
5. Manual gearbox only: Release clip and
disconnect clutch fluid supply hose from
reservoir.
CAUTION: Always fit plugs to open
connections to prevent contamination.
6.Remove 2 nuts and washers securing master
cylinder to servo.
7.Remove master cylinder. Refit
1.Clean master cylinder and servo mating
surfaces.
2.Align push rod and position master cylinder to
servo.
3.Fit nuts and washers securing master cylinder
to servo and tighten to 25 Nm (18 lbf.ft).
4.Connect primary and secondary brake pipes,
and tighten unions to 25 Nm (18 lbf.ft).
5. Manual gearbox only: Connect clutch fluid
hose to reservoir, secure with clip.
6.Connect fluid level switch multiplug.
7.Bleed brake system using TestBook/T4.

+ BRAKES, ADJUSTMENTS, Brake
system bleeding.