Opel Frontera UBS. Service manual — part 1083
5A–5
BRAKE CONTROL SYSTEM
FR
Front Right
GEN
Generator
MV
Millivolts
RL
Rear Left
RR
Rear Right
RPS
Revolution per Second
VDC
Volts DC
VAC
Volts AC
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:
D
Box Wrench
D
Brake Fluid
D
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 to
observe these precautions may result in Anti-lock Brake
System damage.
D
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.
D
The EHCU and valve block connectors should never
be connected or disconnected with the ignition “ON” .
D
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.
D
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:
D
Suspected harness damage.
D
Poor mating of connector halves or terminals not fully
seated in the connector body (backed out).
D
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:
D
Be sure to give a test drive on a wide, even road with
little traffic.
D
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
When the ignition is first moved from “OFF” to “RUN” , the
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
Step
Action
Yes
No
1
1. Customer complaint.
2. Questioning to customer.
3. Basic inspection (Refer to “Basic inspection procedure”)
Using TECH 2?
Go to Step 2
Go to Step 4
2
Make sure of DTC by mode “F0: Diagnostic Trouble Codes”.
Is EHCU including DTC?
Go to Step 3
Go to Step 5
3
1. 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
4
Check 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
5
1. Reconnect all components and ensure all component are
properly mounted.
2. Clear diagnostic trouble code.
Was this step finished?
Finished
Go to Step 5
5A–7
BRAKE CONTROL SYSTEM
Basic Inspection Procedure
1. Basic Inspection of System Brake
Step
Action
Yes
No
1
Is the fluid level normal?
Go to Step 2
Replenish with
fluid.
Go to Step 2
2
Does fluid leak?
Repair.
Go to Step 3
Go to Step 3
3
Is the booster functioning normal?
Go to Step 4
Repair.
Go to Step 4
4
Is the pad and rotor normal?
Go to Step 5
Repair.
Go to Step 5
5
Reconnect all components and ensure all component are
properly mounted.
Was this step finished?
Finished
Go to Step 5
2. Inspection of Front Axle Switch
Step
Action
Yes
No
1
Turn the key switch on and shift the T/F to 4WD position.
Does the 4WD light come on?
Go to Step 2
Repair.
Go to Step 2
2
Reconnect all components and ensure all components are
properly mounted.
Was this step finished?
Finished
Go to Step 2
3. Ground Inspection
Step
Action
Yes
No
1
Are ABS—related ground points ok?
Go to Step 2
Repair.
Go to Step 2
2
Reconnect all components and ensure all components are
properly mounted.
Was this step finished?
Finished
Go to Step 2
5A–8
BRAKE CONTROL SYSTEM
Tech 2 Scan Tool
From 98 MY, Isuzu dealer service departments are
recommended to use Tech 2. Please refer to Tech 2 scan
tool user guide.
901RW257
Legend
(1) PCMCIA Card
(2) SAE 16/19 Adaptor
(3) DLC Cable
(4) Tech–2
Нет комментариевНе стесняйтесь поделиться с нами вашим ценным мнением.
Текст