lock ISUZU TF SERIES 2004 Manual PDF

BRAKE CONTROL SYSTEM 5A-21

Computer System Service Precautions
The Anti-lock Brake System and Electronic Brake-force
Distribution interfaces directly with the Electronic
Hydraulic Control Unit (EHCU) which is a control
computer that is similar in some regards to the Engine
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
5-8840-0366-0 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 and Electronic Brake-force Distribution
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”.
Note:
 If only rear wheels are rotated using jacks or drum
tester, the system will diagnose a speed sensor
malfunction and the “ABS and Brake” warning lamp
will illuminate. But actually no trouble exists. When
the DTC is not detected and the ABS and BRAKE
warning lamp is on, “How to erase code” is
performed and a ABS and BRAKE warning lamp
are off.
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) and
Electronic Brake-force Distribution (EBD) System
requires a large quantity of electricity. In this case, wait
until the battery is recharged, or set the ABS and EBD
to a non-operative state by removing the fuse for the
ABS. After the battery has been recharged, stop the
engine and install the ABS fuse. Start the engine again,
and confirm that the ABS warning Lamp 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.

Test Driving ABS Complaint Vehicles
In case that there has been an abnormality in the
lighting pattern of “ABS” warning lamp, the fault can be
located in accordance with the “DIAGNOSIS BY “ABS”
WARNING LAMP 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.
Note: The DTC cannot be cleared if the vehicle speed
does not exceed about 6km/h (4mph) at DTC, even
though the repair operation is completed.
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 a small traffic.
 If an abnormality is detected, be sure to suspend
the test and start trouble diagnosis at once.

5A-22 BRAKE CONTROL SYSTEM

“ABS” Warning Lamp
When ABS and trouble occurs to actuate “ABS”
warning lamp, the trouble code corresponding to the
trouble is stored in the EHCU. Only ordinary brake is
available with ABS being unactuated. Even when
“ABS” warning lamp 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 lamp is lit
normally even though the trouble code is stored.
NOTE: Illumination of the “ABS” warning lamp indicates
that anti-lock braking is no longer available. Power
assisted braking without anti-lock control is still
available.

Normal Operation
“ABS ” Warning Lamp
When the ignition is first moved from “OFF” to “RUN”,
the amber “ABS” warning lamp will turn “ON”. The
“ABS” warning lamp 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 lamp should remain “OFF”
at all other times.

Brake (EBD) Warning Lamp

825L300001
Vehicles equipped with the EBD (Electronic Brake-force
Distribution) System have an have “Brake” warning
lamp in the instrument panel.
If ABS warning lamp and Brake warning lamp are turn
"ON", then EBD is failed. ( Parking brake switch is
"OFF")
In the following conditions, EBD warning lamp is "ON".
 Starter switch is "ON", engine "OFF".
( Parking brake switch is "OFF")
If engine is started, then EBD warning lamp is "OFF".
( Parking brake switch is "OFF")

5A-28 BRAKE CONTROL SYSTEM

Isolation Valve Test
Purpose: The purpose of this test is to detect brake
pipe and valve line harness wire for wrong connections
and valve trouble.
This test will help you confirm the result of your repair
service including the removal/reinstallation of brake
pipe, valve line harness and valve.
Test conditions: The ignition key is in the “ON” position
with the four wheels lifted up. The brake pedal is
stepped on, released and stepped on again with the
parking brake released.
Test procedure:
1. Connect Tech 2 with the vehicle, and select
Actuaor Test from the menus.
2. Select a Solenoid Valve Test Menu from the
Actuaor Test Menus.

060L300002
3. Select Isolation Valve from the Valve Select Menus.
4. Step on the brake pedal.
5. Release the brake pedal.
6. Make sure that the Isolation Valve “ON” aimed at by
Tech 2 and the wheel locked position are the same.
If different, check brake pipe, valve line harness
wiring and H/UNIT. Repair is needed if abnormality
is found.
7. Conduct Step 2 through Step 5 above on all the
four wheels.

060L300002
CAUTION: When conducting this test, please
observe the following cautions.

1. Do not start the engine.
2. Lift up the vehicle at a level floor.





Secure a clearance from the floor surface
enough to allow the lifted tire to rotate.
3. Maintain the lift up.
4. Wipe the floor surface to remove water and oil
so that the surface may become unslippery.
5. Do not load the vehicle.





When lifting up the vehicle, be sure to
observe the lifting up points. Refer to
vehicle lifting points in 0A section.

BRAKE CONTROL SYSTEM 5A-39

Symptom Diagnosis
The symptoms that cannot be indicated by warning
lamp 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 are locked.

4. Brake pedal feel is abnormal.
5. Braking sound (from EHCU) is heard while not
braking.
6. No ABS warning lamp
These are all attributable to problems which cannot be
detected by EHCU self-diagnosis. Use the customer
complaint and a test to determine which symptom is
present.
ABS Works Frequently But Vehicle Does Not Decelerate

Step Action
Value(s) Yes No
1 Is braking force distribution normal between front
and rear of vehicle?
- Go to Step 2 Repair brake
parts.
Go to Step 7
2 Are axle parts installed normally?
- Go to Step 3 Repair axle
parts.
Go to Step 7
3 Is there play in each or any wheel speed sensor?
- Repair wheel
speed sensor.
Go to Step 7 Go to Step 4
4 Is there damage, or powered iron sticking to each or
any wheel speed sensor/sensor rotor?
- Replace
wheel speed
sensor or
sensor rotor.
Go to Step 8 Go to Step 5
5 Is the each wheel speed sensor output normal?
- Go to Step 6 Replace
wheel speed
sensor or
repair
harness.
Go to Step 7
6 Is the 4WD control system function normal?
- 2-4WD Repair
or Go to Step
7 Repair or
replace 2-
4WD control
System.
Go to Step 7
7 Reconnect all components, ensure all components
are properly mounted.
Was this step finished?
- Repeat the
“Basic
diagnostic
flow chart” Go to Step 7

5A-40 BRAKE CONTROL SYSTEM

Uneven Braking Occurs While ABS Works

Step Action
Value(s) Yes No
1 Is there play in each or any sensor?
- Repair.
Go to Step 5 Go to Step 2
2 Damage or powdered iron sticking to each or any
sensor/sensor rotor?
- Repair.
Go to Step 5 Go to Step 3
3 Is the each sensor output normal?
- Go to Step 4 Replace
sensor or
repair
harness.
Go to Step 5
4 Is brake pipe connecting order correct?
Note: Check the EHCU type for specification, when
the EHCU is replaced.
(Specification; 2WD Model or 4WD Model) - Replace
EHCU.
Go to Step 5 Reconnect
brake pipe
correctly.
Go to Step 5
5 Reconnect all components, ensure all components
are properly mounted.
Was this step finished?
- Repeat the
“Basic
diagnostic
flow chart” Go to Step 5

The Wheels Are Locked

Step Action Value(s) Yes No
1 Is ABS working?
- Go to Step 2 Go to Step 4
2 Is vehicle speed under 5 km/h?
- Go to Step 3 Normal.
3 Is the each sensor output normal?
- Go to Step 4 Replace
sensor or
repair
harness.
Go to Step 6
4 Is 2-4WD system function normal?
- Go to Step 5 Replace 2-
4WD controll
unit or repair
harness.
Go to Step 6
5 Is EHCU grounded properly?
Note: Check the EHCU type for specification, when
the EHCU is replaced.
(Specification; 2WD Model or 4WD Model) - Replace
EHCU.
Go to Step 6 Repair.
Go to Step 6
6 Reconnect all components, ensure all components
are properly mounted.
Was this step finished?
- Repeat the
“Basic
diagnostic
flow chart” Go to Step 6

ANTI-LOCK BRAKE SYSTEM 5B-1

SECTION 5B
BRAKES
ANTI-LOCK BRAKE SYSTEM
TABLE OF CONTENTS
PAGE
Service Precaution ...................................................................................................................... 5B – 2
Torque Specifications ................................................................................................................ 5B – 3
Electronic Hydraulic Control Unit ........................................................................................... 5B – 7
Electronic Hydraulic Control Unit and Associated Parts ............................................ 5B – 7
Removal .................................................................................................................................... 5B – 7
Installation ................................................................................................................................ 5B – 7
Front Wheel Speed Sensor ....................................................................................................... 5B – 8
Front Wheel Speed Sensor and Associated Parts ........................................................ 5B – 8
Removal .................................................................................................................................... 5B – 9
Inspection and Repair ........................................................................................................... 5B – 9
Installation ................................................................................................................................ 5B – 10
Rear Wheel Speed Sensor ........................................................................................................ 5B – 11
Rear Wheel Sensor and Associated Parts ....................................................................... 5B – 11
Removal .................................................................................................................................... 5B – 11
Inspection and Repair ........................................................................................................... 5B – 11
Installation ................................................................................................................................ 5B – 12
Front Speed Sensor Rotor ........................................................................................................ 5B – 13
Front Sensor Rotor and Associated Parts ....................................................................... 5B – 13
Removal .................................................................................................................................... 5B – 13
Inspection and Repair ........................................................................................................... 5B – 14
Installation ................................................................................................................................ 5B – 14
Rear Speed Sensor Rotor .......................................................................................................... 5B – 16
Rear Sensor Rotor and Associated Parts ........................................................................ 5B – 16
Removal .................................................................................................................................... 5B – 16
Inspection and Repair ........................................................................................................... 5B – 17
Installation ................................................................................................................................ 5B – 17
G-Sensor ........................................................................................................................................ 5B – 19
G-Sensor and Associated Parts ......................................................................................... 5B – 19

5B -2 ANTI-LOCK BRAKE SYSTEM

Removal .................................................................................................................................... 5B – 19
Installation ................................................................................................................................ 5B – 19
Special Tools ........................................................................................................................... 5B – 20


Service Precaution
WARNING: THIS VEHICLE HAS 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.

ANTI-LOCK BRAKE SYSTEM 5B-3

Torque Specifications
Electronic Hydraulic Control Unit

This illustration is based
on RHD model
E05R300007

5B -4 ANTI-LOCK BRAKE SYSTEM

4




2 Front Speed Sensor

E05R300002

ANTI-LOCK BRAKE SYSTEM 5B-5

Front Speed Sensor (4




4, 4




2 High Ride)

E05R300003