Range Rover. Manual — part 199
ABS
11
DESCRIPTION AND OPERATION
ETC control valves - up to 99MY - 7 & 8
The ETC control valves are optional on vehicles up to
99MY. The ETC inlet solenoid valve (7) is normally
closed and the ETC isolating solenoid valve (8) is
normally open when ETC operation is not required.
When ETC operation is required, the inlet solenoid
valve opens allowing fluid from the power circuit to
flow to the rear ABS solenoid control valves.
Simultaneously, the ETC isolating solenoid valve
closes, isolating the connection to the PCRV. The
ABS ECU energises the applicable ABS solenoid
valve to pressurise the applicable rear wheel brake.
ETC control valves - from 99MY - 7 & 8
The ETC control valves are standard on vehicles from
99MY. The ETC inlet solenoid valve (7) is normally
closed and the ETC isolating solenoid valve (8) is
normally open when ETC operation is not required.
When ETC operation is required, the inlet solenoid
valve opens allowing fluid from the power circuit to
flow to the power valve. The power valve is actuated
by the pressure and opens to allow fluid from the
power circuit to flow directly to the front ABS solenoid
control valves and to the rear solenoid control valves
via the PCRV. The ETC isolating solenoid valve
closes isolating the return flow from each ABS
solenoid control valve. The ABS ECU energises the
applicable ABS solenoid valve(s) to pressurise the
applicable front and/or rear wheel brake.
ABS power unit
The ABS power unit consists of an electrically driven
pump, a pressure switch and an accumulator.
The pressure switch incorporates three
electro-mechanical switches: one for the pump,
another, at a different pressure setting, to illuminate
the pressure warning lamp. The latter switch plus a
third switch inform the ECU of low pressure and that
ABS function should cease while pressure remains
low.
The pump also incorporates a non-return valve and a
pressure relief valve to protect the system.
NOTE: The pump and pressure switch are
not serviceable, if failure occurs a new unit
must be fitted.
The diaphragm type accumulator is fitted to the power
unit. The accumulator is precharged with nitrogen at
up to 80 bar. Its function is to store hydraulic energy
ready for the next brake application.
NOTE: Accumulator replacement is
possible if failure occurs. Correct disposal
of old accumulators is essential.
See
Repair.
Pressure Conscious Reducing Valve (PCRV)
The PCRV is located adjacent to the brake
booster/ABS modulator unit. It is connected between
the power valve and ABS solenoid valves for the rear
axle. Its function is to limit brake pressure to rear axle.
NOTE: The PCRV is not a serviceable item,
if failure occurs a new unit must be fitted.
Brake calipers - front and rear
NOTE: To identify separate hydraulic
circuits, they are referred to as
HYDROSTATIC and POWER circuits.
Power circuit - Consists of rear calipers and servo
cylinders, supplied by direct hydraulic power from the
power valve.
Hydrostatic circuit - Consists of servo cylinders
supplied by master cylinder pressure. The front
calipers are supplied with direct hydraulic energy from
the servo cylinders, comprising a combination of
master cylinder pressure and direct hydraulic power.
70
BRAKES
NEW RANGE ROVER
12
DESCRIPTION AND OPERATION
ABS Electronic Control Unit - ECU
ABS/ETC operation is controlled by the ECU. The
ECU is attached to a bracket which in turn is attached
to the bulkhead. A closing plate beneath the
passenger side fascia provides access to the ECU.
The ECU is connected to the ABS harness by a 35 pin
connector on up to 99MY vehicles and by 9, 15 and
18 pin connectors on vehicles from 99MY.
When system faults are detected by the ECU, warning
lamps in the instrument pack can be illuminated for
ABS, ETC and braking system faults. Certain faults
are also displayed in the instrument pack message
centre. Refer to Operation - Warning lamps for lamp
and message centre operation.
The ABS ECU generates a digital road speed signal
from the average speed of the four wheels. The ABS
ECU passes the road speed signal to the BeCM. The
BeCM outputs the road speed signal to the following
interfaces:
•
Engine Control Module (ECM)
•
Cruise control ECU (V8 only)
•
Instrument pack
•
Air Temperature Control (ATC) ECU
•
In-Car Entertainment (ICE)
•
Electronic Air Suspension (EAS) ECU
•
Electronic Automatic Transmission (EAT) ECU.
The ABS ECU also outputs a rough road signal to the
ECM on V8 engine vehicles only. The digital rough
road signal is generated from the difference in
rotational speed of each wheel.
The ECU is a non-serviceable item, it must be
replaced if failure occurs.
ABS
13
DESCRIPTION AND OPERATION
This page is intentionally left blank
70
BRAKES
NEW RANGE ROVER
14
DESCRIPTION AND OPERATION
ABS ECU connector pin details - up to 99MY
ABS ECU connector face view
35 pin connector No.C116
Pin No.
Description
Input/Output
1
ABS valve relay (battery supply)
Input
2
Brake booster/ABS modulator - ETC normally open
valve
Output
3
BeCM - ETC information lamp
Output
4
Brake booster/ABS modulator - Rear right inlet valve
Output
5
Brake booster/ABS modulator - Rear right outlet valve
Output
6
Brake booster/ABS modulator - Front right inlet valve
Output
7
Brake booster/ABS modulator - Front right outlet valve
Output
8
ABS valve relay coil
Output
9
Ignition supply
Input
10
Brake switch 2 (normally closed)
Input
11
Brake booster/ABS modulator - Isolating inlet valve
Output
12
Brake booster/ABS modulator - Isolating outlet valve
Output
13
Diagnostic socket - K line
Input
14
Diagnostic socket - L line
Input
15
Front left wheel speed sensor
Input
16
Rear right wheel speed sensor
Input
Нет комментариевНе стесняйтесь поделиться с нами вашим ценным мнением.
Текст