lock OPEL FRONTERA 1998 Workshop Manual

5A–4
BRAKE CONTROL SYSTEM
normal braking when a malfunction has occurred in the
ABS.
The EHCU has a self-diagnosing function which can
indicate faulty circuits during diagnosis.
The EHCU is mounted on the engine compartment front
right side. It consists of a Motor, Plunger Pump, Solenoid
Valves and Check Valve.
On the outside, the relay box containing a motor relay and
a valve relay is installed.
Solenoid Valves: Reduces or holds the caliper fluid
pressure for each front disc brake or both rear disc brakes
according to the signal sent from the EHCU.
Reservoir: Temporarily holds the brake fluid that returns
from the front and rear disc brake caliper so that pressure
of front disc brake caliper can be reduced smoothly.
Plunger Pump: Feeds the brake fluid held in the reservoir
to the master cylinder.
Motor: Drives the pump according to the signal from
EHCU.
Check Valve: Controls the brake fluid flow.
ABS Warning Light
821RW033Vehicles equipped with the Anti-lock Brake System have
an amber “ABS” warning light in the instrument panel.
The “ABS” warning light will illuminate if a malfunction in
the Anti-lock Brake System is detected by the Electronic
Hydraulic Control Unit (EHCU). In case of an electronic
malfunction, the EHCU will turn “ON” the “ABS” warning
light and disable the Anti-lock braking function.
The “ABS” light will turn “ON” for approximately three
seconds after the ignition switch is to the “ON” position.
If the “ABS” light stays “ON” after the ignition switch is the
“ON” position, or comes “ON” and stays “ON” while
driving, the Anti-lock Brake System should be inspected
for a malfunction according to the diagnosis procedure.
Wheel Speed Sensor
It consists of a sensor and a rotor. The sensor is attached
to the knuckle on the front wheels and to the axle shaft
bearing holder on the rear wheels.
The rotor is press-fit in the axle shaft.The flux generated from electrodes magnetized by a
magnet in the sensor varies due to rotation of the rotor,
and the electromagnetic induction generates alternating
voltage in the coil. This voltage draws a “sine curve” with
the frequency proportional to rotor speed and it allows
detection of wheel speed.
G-Sensor
The G-sensor installed inside the center console detects
the vehicle deceleration speed and sends a signal to the
EHCU. In 4WD operation, all four wheels may be
decelerated in almost the same phase, since all wheels
are connected mechanically.
This tendency is noticeable particularly on roads with low
friction coefficient, and the ABS control is adversely
affected.
The G-sensor judges whether the friction coefficient of
road surface is low or high, and changes the EHCU’s
operating system to ensure ABS control.
Normal and Anti-lock Braking
Under normal driving conditions, the Anti-lock Brake
System functions the same as a standard power assisted
brake system. However, with the detection of wheel
lock-up, a slight bump or kick-back will be felt in the brake
pedal. This pedal “bump” will be followed by a series of
short pedal pulsations which occurs in rapid succession.
The brake pedal pulsation will continue until there is no
longer a need for the anti-lock function or until the vehicle
is stopped. A slight ticking or popping noise may be heard
during brake applications when the Anti-lock features is
being used.
When the Anti-lock feature is being used, the brake pedal
may rise even as the brakes are being applied. This is
also normal. Maintaining a constant force on the pedal
will provide the shortest stopping distance.
Brake Pedal Travel
Vehicles equipped with the Anti-lock Brake System may
be stopped by applying normal force to the brake pedal.
Although there is no need to push the pedal beyond the
point where it stops or holds the vehicle, by applying more
force the pedal will continue to travel toward the floor.
This extra brake pedal travel is normal.
Acronyms and Abbreviations
Several acronyms and abbreviations are commonly used
throughout this section:
ABS
Anti-lock Brake System
CKT
Circuit
DLC
Data Link Connector
EHCU
Electronic Hydraulic Control Unit
FL
Front Left

5A–5 BRAKE CONTROL SYSTEM
FR
Front Right
GEN
Generator
MV
Millivolts
RL
Rear Left
RR
Rear RightRPS
Revolution per Second
VDC
Vo l t s D C
VA C
Vo l t s A C
W/L
Warning Light
WSS
Wheel Speed Sensor
General Diagnosis
General Information
ABS malfunction can be classified into two types, those
which can be detected by the ABS warning light and those
which can be detected as a vehicle abnormality by the
driver.
In either case, locate the fault in accordance with the
“BASIC DIAGNOSTIC FLOWCHART” and repair.
Please refer to Section 5C for the diagnosis of
mechanical troubles such as brake noise, brake judder
(brake pedal or vehicle vibration felt when braking),
uneven braking, and parking brake trouble.
ABS Service Precautions
Required Tools and Items:
Box Wrench
Brake Fluid
Special Tool
Some diagnosis procedures in this section require the
installation of a special tool.
J-39200 High Impedance Multimeter
When circuit measurements are requested, use a circuit
tester with high impedance.
Computer System Service Precautions
The Anti-lock Brake System interfaces directly with the
Electronic Hydraulic Control Unit (EHCU) which is a
control computer that is similar in some regards to the
Powertrain Control Module. These modules are designed
to withstand normal current draws associated with
vehicle operation. However, care must be taken to avoid
overloading any of the EHCU circuits. In testing for opens
or shorts, do not ground or apply voltage to any of the
circuits unless instructed to do so by the appropriate
diagnostic procedure. These circuits should only be
tested with a high impedance multimeter (J-39200) or
special tools as described in this section. Power should
never be removed or applied to any control module with
the ignition in the “ON” position.
Before removing or connecting battery cables, fuses or
connectors, always turn the ignition switch to the “OFF”
position.
General Service Precautions
The following are general precautions which should be
observed when servicing and diagnosing the Anti-lock
Brake System and/or other vehicle systems. Failure toobserve these precautions may result in Anti-lock Brake
System damage.
If welding work is to be performed on the vehicle using
an electric arc welder, the EHCU and valve block
connectors should be disconnected before the
welding operation begins.
The EHCU and valve block connectors should never
be connected or disconnected with the ignition “ON” .
EHCU of the Anti-lock Brake System are not
separately serviceable and must be replaced as
assemblies. Do not disassemble any component
which is designated as non-serviceable in this
Section.
If only rear wheels are rotated using jacks or drum
tester, the system will diagnose a speed sensor
malfunction and the “ABS” warning light will
illuminate. But actually no trouble exists. After
inspection stop the engine once and re-start it, then
make sure that the “ABS” warning light does not
illuminate.
If the battery has been discharged
The engine may stall if the battery has been completely
discharged and the engine is started via jumper cables.
This is because the Anti-lock Brake System (ABS)
requires a large quantity of electricity. In this case, wait
until the battery is recharged, or set the ABS to a
non-operative state by removing the fuse for the ABS
(40A). After the battery has been recharged, stop the
engine and install the ABS fuse. Start the engine again,
and confirm that the ABS warning light does not light.
Note on Intermittents
As with virtually any electronic system, it is difficult to
identify an intermittent failure. In such a case duplicating
the system malfunction during a test drive or a good
description of vehicle behavior from the customer may be
helpful in locating a “most likely” failed component or
circuit. The symptom diagnosis chart may also be useful
in isolating the failure. Most intermittent problems are
caused by faulty electrical connections or wiring. When
an intermittent failure is encountered, check suspect
circuits for:
Suspected harness damage.
Poor mating of connector halves or terminals not fully
seated in the connector body (backed out).
Improperly formed or damaged terminals.

5A–6
BRAKE CONTROL SYSTEM
Test Driving ABS Complaint Vehicles
In case that there has been an malfunction in the lighting
pattern of “ABS” warning light, the fault can be located in
accordance with the “DIAGNOSIS BY “ABS” WARNING
LIGHT ILLUMINATION PATTERN” . In case of such
trouble as can be detected by the driver as a vehicle
symptom, however, it is necessary to give a test drive
following the test procedure mentioned below, thereby
reproducing the symptom for trouble diagnosis on a
symptom basis:
1. Start the engine and make sure that the “ABS” W/L
goes OFF. If the W/L remains ON, it means that the
Diagnostic Trouble Code (DTC) is stored. Therefore,
read the code and locate the fault.
2. Start the vehicle and accelerate to about 30 km/h (19
mph) or more.
3. Slowly brake and stop the vehicle completely.
4. Then restart the vehicle and accelerate to about 40
km/h (25 mph) or more.
5. Brake at a time so as to actuate the ABS and stop the
vehicle.
6. Be cautious of abnormality during the test. If the W/L
is actuated while driving, read the DTC and locate the
fault.
7. If the abnormality is not reproduced by the test, make
best efforts to reproduce the situation reported by the
customer.
8. If the abnormality has been detected, repair in
accordance with the “SYMPTOM DIAGNOSIS” .NOTE:Be sure to give a test drive on a wide, even road with
little traffic.
If an abnormality is detected, be sure to suspend the
test and start trouble diagnosis at once.
“ABS” Warning Light
When ABS trouble occurs and actuates when possible
the “ABS” warning light, the trouble code corresponding
to the trouble is stored in the EHCU. Only the ordinary
brake system is available when the ABS is turned off.
When the “ABS” warning light is actuated, if the starter
switch is set ON after setting it OFF once, the EHCU
checks up on the entire system and, if there is no
abnormality, judges ABS to work currently and the
warning light works normally even though the trouble
code is stored.
NOTE: Illumination of the “ABS” warning light indicates
that anti-lock braking is no longer available. Power
assisted braking without anti-lock control is still available.
Normal Operation
“ABS” Warning Light
W h e n t h e i g n i t i o n i s f i r s t m o v e d f r o m “ O F F ” t o “ R U N ” , t h e
amber “ABS” warning light will turn “ON” . The “ABS”
warning light will turn “ON” during engine starting and will
usually stay “ON” for approximately three seconds after
the ignition switch is returned to the “ON” position. The
warning light should remain “OFF” at all other times.
Basic Diagnostic Flow Chart
StepActionYe sNo
11. Customer complaint.
2. Questioning to customer.
3. Basic inspection (Refer to “Basic inspection procedure”)
Using TECH 2?
Go to Step 2Go to Step 4
2Make sure of DTC by mode “F0: Diagnostic Trouble Codes”.
Is EHCU including DTC?
Go to Step 3Go to Step 5
31. Repair of faulty part.
2. Elimination of DTC.
3. Inspection of “ABS” W/L Illumination pattern with ignition SW
“ON”.
4. Test drive.
Does repeat trouble?
Repeat the
diagnosis it the
symptom or DTC
appears again Go
to Step 1
Go to Step 5
4Check if the DTC is stored.
Is EHCU including DTC?
Go to Step 3
Trouble diagnosis
based on
symptom (Refer
to “SYMPTOM
DIAGNOSIS”) Go
to Step 3
51. Reconnect all components and ensure all component are
properly mounted.
2. Clear diagnostic trouble code.
Was this step finished?
FinishedGo to Step 5

5A–35 BRAKE CONTROL SYSTEM
Symptom Diagnosis
The symptoms that cannot be indicated by the warning
light can be divided in the following five categories:
1. ABS works frequently but vehicle does not
decelerate.
2. Uneven braking occurs while ABS works.
3. The wheels lock during braking.4. Brake pedal feel is abnormal.
5. Braking sound (from EHCU) is heard while not
braking.
These are all attributable to problems which cannot be de-
tected by EHCU self-diagnosis. Use the customer com-
plaint and a test to determine which symptom is present.
Then follow the appropriate flow chart listed below.
NoSymptomDiagnostic Flow ChartsNo.Sym tomWithout TECH 2With TECH 2
1ABS works frequently but vehicle does not decelerate.Chart A–1Chart TA–1
2Uneven braking occurs while ABS works.Chart A–2—
3The wheels are locked.Chart A–3Chart TA–3
4Brake pedal feel is abnormal.Chart A–4—
5Braking sound (from EHCU) is heard while not braking. Chart A–5Chart TA–5
Chart A–1 ABS Works Frequently But Vehicle Does Not Decelerate
StepActionYe sNo
11. Turn key off.
2. G Sensor connector and EHCU connector disconnected.
Is there continuity between EHCU terminals 26 and 8?
Go to Step 2Go to Step 3
2Connect EHCU connector.
Is there continuity between the G sensor and the EHCU?
Go to Step 3
Repair circuit.
Go to Step 1
3Is the G sensor normal? (Refer to chart B-5)
Go to Step 4
Replace G
sensor.
Go to Step 11
4Is braking force distribution normal between the front and rear of
the vehicle?
Go to Step 5
Repair brake
parts.
Go to Step 11
5Are axle parts installed normally?Go to Step 6Repair axle parts.
Go to Step 11
6Is there play in each wheel speed sensor?Repair wheel
speed sensor.
Go to Step 11
Go to Step 7
7Is there damage, or powered iron sticking to each wheel speed
sensor/sensor ring?Replace sensor
or sensor ring.
Go to Step 11
Go to Step 8
8Is the output of each wheel speed sensor normal? (Refer to chart
C-1 or TC-1)
Go to Step 9
Replace wheel
speed sensor or
repair harness.
Go to Step 11
9Is the input of transmission normal? (Refer to chart C-2 or TC-2)
Go to Step 10
Replace switch or
repair harness.
Go to Step 11

5A–36
BRAKE CONTROL SYSTEM
StepNo Ye s
Action
10Is the input of 4WD controller normal?
Go to Step 11
Replace
controller or
repair harness.
Go to Step 11
11Reconnect all components and ensure all components are
properly mounted.
Was this step finished?Repeat the “Basic
diagnostic flow
chart.”
Go to Step 11
Chart TA-1 ABS Works Frequently But Vehicle Does Not Decelerate (Use TECH 2)
StepActionYe sNo
11. Connect TECH 2.
2. Make sure of the output conditions of each wheel speed
sensor by mode “F1: Data Display”.
Is the output of each sensor normal?
Go to Step 2
Replace wheel
speed sensor.
Go to Step 3
2Return to Chart A-1.
Was the Chart A-1 finished?
Go to Step 3Go to Step 2
3Reconnect all components, ensure all components are properly
mounted.
Was this step finished?Repeat the “Basic
diagnostic flow
chart.”
Go to Step 3
Chart A-2 Uneven Braking Occurs While ABS Works
StepActionYe sNo
1Is there play in each sensor?Repair.
Go to Step 5
Go to Step 2
2Is there damage or powdered iron sticking to each sensor/sensor
ring?Repair.
Go to Step 5
Go to Step 3
3Is the output of each sensor normal? (Refer to chart C-1 or TC-1)
Go to Step 4
Replace sensor
or repair harness.
Go to Step 5
4Is brake pipe connecting order correct?
Replace EHCU.
Go to Step 5
Reconnect brake
pipe correctly.
Go to Step 5
5Reconnect all components, ensure all components are properly
mounted.
Was this step finished?Repeat the “Basic
diagnostic flow
chart.”
Go to Step 5
Chart A-3, TA-3 The Wheels Are Locked
StepActionYe sNo
1Is ABS working?Go to Step 2Go to Step 6
2Is vehicle speed under 10 km/h (6mph)?Normal.Go to Step 3
3Is sensor output normal? (Chart C-1 or TC-1)
Go to Step 4
Replace sensor
or repair harness.
Go to Step 9
4Is transmission input normal? (Chart C-2 or TC-2)
Go to Step 5
Replace SW or
repair harness.
Go to Step 9

5B–1 ANTI–LOCK BRAKE SYSTEM
BRAKES
ANTI-LOCK BRAKE SYSTEM
CONTENTS
Service Precaution 5B–1. . . . . . . . . . . . . . . . . . . . . .
Electronic Hydraulic Control Unit 5B–2. . . . . . . . . .
Electronic Hydraulic Control Unit and
Associated Parts 5B–2. . . . . . . . . . . . . . . . . . . . . .
Removal 5B–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 5B–2. . . . . . . . . . . . . . . . . . . . . . . . . . . .
G-Sensor 5B–3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Removal 5B–3. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Inspection and Repair 5B–3. . . . . . . . . . . . . . . . . .
Installation 5B–3. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Front Wheel Speed Sensor 5B–4. . . . . . . . . . . . . . . Front Wheel Speed Sensor and
Associated Parts 5B–4. . . . . . . . . . . . . . . . . . . . . .
Removal 5B–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Inspection and Repair 5B–5. . . . . . . . . . . . . . . . . .
Installation 5B–5. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Rear Wheel Speed Sensor 5B–6. . . . . . . . . . . . . . .
Rear Wheel Speed Sensor and
Associated Parts 5B–6. . . . . . . . . . . . . . . . . . . . . .
Removal 5B–6. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Inspection and Repair 5B–6. . . . . . . . . . . . . . . . . .
Installation 5B–6. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Service Precaution
WARNING: IF SO EQUIPPED WITH A
SUPPLEMENTAL RESTRAINT SYSTEM(SRS),
REFER TO THE SRS COMPONENT AND WIRING
LOCATION VIEW IN ORDER TO DETERMINE
WHETHER YOU ARE PERFORMING SERVICE ON OR
NEAR THE SRS COMPONENTS OR THE SRS
WIRING. WHEN YOU ARE PERFORMING SERVICE
ON OR NEAR THE SRS COMPONENTS OR THE SRS
WIRING, REFER TO THE SRS SERVICE
INFORMATION. FAILURE TO FOLLOW WARNINGS
COULD RESULT IN POSSIBLE AIR BAG
DEPLOYMENT, PERSONAL INJURY, OR
OTHERWISE UNNEEDED SRS SYSTEM REPAIRS.
CAUTION: Always use the correct fastener in the
proper location. When you replace a fastener, use
ONLY the exact part number for that application.
ISUZU will call out those fasteners that require a
replacement after removal. ISUZU will also call out
the fasteners that require thread lockers or thread
sealant. UNLESS OTHERWISE SPECIFIED, do not
use supplemental coatings (Paints, greases, or other
corrosion inhibitors) on threaded fasteners or
fastener joint interfaces. Generally, such coatings
adversely affect the fastener torque and the joint
clamping force, and may damage the fastener. When
you install fasteners, use the correct tightening
sequence and specifications. Following these
instructions can help you avoid damage to parts and
systems.CAUTION: Replace all components included in
repair kits used to service this system. Lubricate
rubber parts with clean, fresh brake fluid to ease
assembly. Do not use shop air with in–line
lubricators on brake parts, as damage to rubber
components may result. If any hydraulic component
is removed or brake line disconnected, it may be
necessary to bleed part or all of the brake system.
NOTE: The use of rubber hoses or parts other than those
furnished specifically for the Anti–lock Brake System may
lead to functional problems requiring major overhaul.

5B–2ANTI–LOCK BRAKE SYSTEM
Electronic Hydraulic Control Unit
Electronic Hydraulic Control Unit and Associated Parts
350RW013
Legend
(1) Connector
(2) Hydraulic Unit ASM(3) Bolts
(4) Nut
(5) Bolt
Removal
1. Remove battery ASM.
2. Remove harness connector.
3. Remove EHCU fixing nuts.
4. Remove brake pipes.
After disconnecting brake pipe, cap or tape the
openings of the brake pipe to prevent the entry of
foreign matter.
5. Remove hydraulic unit fixing nuts.
Installation
To install, follow the removal steps in the reverse order,
noting the following points:
To r q u e
Hydraulic unit fixing nuts : 22 Nꞏm (2.2kgꞏm/16
lb ft)
Ground cable : 14 Nꞏm (1.4kgꞏm/10 lb ft)
Brake pipe (joint bolts) : 16 Nꞏm (1.6kgꞏm/12
lb ft)
After installing the hydraulic unit, bleed brakes
completely. Refer to Servicing in Power Assisted
Brake System section.

5B–3 ANTI–LOCK BRAKE SYSTEM
G-Sensor
Removal
350RX001
1. Remove center console.
Refer to Consoles in Body and Accessories
section.
2. Remove clip from G-sensor connector (1), then
disconnect connector.
3. Remove G-sensor assembly fixing bolt (2).
4. Remove G-sensor assembly (3).
Inspection and Repair
Refer to Chart B-5 in Brake Control System section.
Installation
1. Install G-sensor assembly (3).
Care should be taken so that the G-sensor is not
installed in the wrong direction.
2. Install G-sensor assembly fixing bolt (2).
Tighten the fixing bolt to the specified torque.
Torque : 10 Nꞏm (1.0kgꞏm/87 lb in)
3. Install G-sensor wiring connector (1).
4. Install center console.
Refer to Consoles in Body and Accessories
section.

5B–4ANTI–LOCK BRAKE SYSTEM
Front Wheel Speed Sensor
Front Wheel Speed Sensor and Associated Parts
350RW012
Legend
(1) Speed Sensor Connector
(2) Sensor Cable Fixing Bolt (Upper side)(3) Sensor Cable Fixing Bolt (Lower side)
(4) Sensor Cable Fixing Bolt (Sensor side)
(5) Speed Sensor
Removal
1. Remove speed sensor connector.
2. Remove sensor cable fixing bolt (Upper side).
3. Remove sensor cable fixing bolt (Lower side).
4. Remove the speed sensor cable fixing bolts (1) and
caliper fixing bolt (2) from caliper side speed sensor
cable bracket (3).
350RW010
5. Remove speed sensor.

5B–5 ANTI–LOCK BRAKE SYSTEM
Inspection and Repair
1. Check the speed sensor pole piece for presence of
foreign materials; remove any dirt, etc.
2. Check the pole piece for damage; replace speed
sensor if necessary.
3. Check the speed sensor cable for short or open
circuit, and replace with a new one if necessary.
To check for cable short or open, bend or stretch the
cable while checking for continuity.
4. Check the sensor ring for damage including tooth
chipping, and if damaged, replace the sensor ring
assembly. Refer to Front Hub and Disc in Drive Shaft
System section.
Installation
1. Install speed sensor and take care not to hit the speed
sensor pole piece during installation.
2. Install speed sensor fixing bolt and tighten the fixing
bolt to the specified torque.
Torque
Sensor side : 8 Nꞏm (0.8kgꞏm/69 lb in)
Caliper side : 155 Nꞏm (15.8kgꞏm/115 lb ft)
350RW011
Legend
(1) Caliper Fixing Bolt
(2) Bracket
(3) Sensor Fixing Bolt
(4) Sensor
(5) Knuckle
(6) Brake Caliper
3. Install speed sensor cable fixing bolt (Lower side) and
tighten the fixing bolt to the specified torque.
Torque : 24 Nꞏm (2.4kgꞏm/18 lb ft)
4. Install speed sensor cable fixing bolt (Upper side) and
tighten the fixing bolt to the specified torque.
Torque : 6 Nꞏm (0.6kgꞏm/52 lb in)NOTE: Confirm that a white line marked on the cable is
not twisted when connecting the speed sensor cable.
5. Install speed sensor connector.