brake sensor ISUZU TF SERIES 2004 Owner's Manual
[x] Cancel search | Manufacturer: ISUZU, Model Year: 2004, Model line: TF SERIES, Model: ISUZU TF SERIES 2004Pages: 4264, PDF Size: 72.63 MB
Page 320 of 4264
5A-4 BRAKE CONTROL SYSTEM
DTC C0277 (Flash Code 77) Power Supply Low Input .................................................... 5A-84
DTC C0278 (Flash Code 78) Power Supply High Input ................................................... 5A-84
DTC C0282 (Flash Code 82) 4 Wheel Drive State Input Signal Failure .......................... 5A-86
DTC C0285 (Flash Code 85) Assembly Error (G-sensor) ................................................ 5A-88
Special Tools ...................................................................................................................... 5A-90
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.
Page 321 of 4264
BRAKE CONTROL SYSTEM 5A-5
General Description
EHCU has controlled ABS (Anti-lock Brake System)
and EBD (Electronic Brake-force Distribution System).
ABS works on all four wheels. EBD system works on
rear 2 wheels. A combination of wheel speed sensor
and Electronic Hydraulic Control Unit (EHCU) can
determine when a wheel is about to stop turning and
adjust brake pressure to maintain best braking. This system helps the driver maintain greater control of
the vehicle under heavy braking conditions.
Note: The Electronic Hydraulic Control Unit (EHCU)
comprises the Hydraulic Unit (H/U) and Control Unit.
This illustration is based on RHD model
C05L300010
Legend
(1) Electronic (6) Front Left Wheel Speed Sensor
(2) Hydraulic (7) Rear Right Wheel Speed Sensor
(3) Hydraulic Unit (H/U) (8) Rear Left Wheel Speed Sensor
(4) Control Unit (9) G-sensor (4WD only)
(5) Front Right Wheel Speed Sensor (10) 2-4WD Control Unit (4WD only)
Page 325 of 4264
BRAKE CONTROL SYSTEM 5A-9
Pressure Isolation (Pressure Maintain)
The electronic-hydraulic control unit is activated when
the brakes are applied.
If the information from the wheel speed sensors
indicates excessive wheel deceleration (imminent
lockup), the first step in the anti-lock sequence is to
isolate the brake pressure being applied by the brake
pedal.
The microprocessor in the Control Unit sends a voltage
to the coil to energize and close the isolation valve.
This prevents any additional fluid pressure applied by
the brake pedal from reaching the wheel. With the
isolation valves closed, unnecessary increase in the
brake pressure is prevented.
C05L300013
Page 329 of 4264
BRAKE CONTROL SYSTEM 5A-13
Connector List
No. Connector face No. Connector face
B-23
Green
Meter-A C-44
WhiteStop Light Switch
B-24
Green
Meter-B C-53
OrangeABS Sensor Front-RH
B-48
Black
G-sensor C-54
OrangeABS Sensor Front-LH
B-54
White
I2 C-67
BlackEHCU
B-56
White
J/B I4 C-107
WhiteJ/B E2
B-58
Black
Data Link Connector C-108
WhiteJ/B E1
B-62
White
Ignition Switch (IGSUB : G1) C-109
SilverBody-LH ; Ground
B-63
White
Ignition Switch (IGSUB : G2) F-4
Gray ABS Sensor Rear
C-2
Silver
Engine Room-RH ; ground H-6
WhiteEngine Room ~ INST
C-36
Silver
Engine Room-LH ; Ground H-7
WhiteEngine Room ~ INST
Page 333 of 4264
BRAKE CONTROL SYSTEM 5A-17
EHCU Pin-outs
C05L300005
EHCU Side
Pin No.
(Harness
side
Pin No.) Pin Function Wire
Color Typical Value Note
1
(C67-11) Power Supply WHT/GRN Battery Voltage Solenoid
2
(C67-10) Ground 1 BLK 0V
(Less than 0.1V) Solenoid, Control Unit
3
(C67-28) Ground 2 BLK 0V
(Less than 0.1V) Motor
4
(C67-27) Power Supply WHT/RED Battery Voltage Motor
5
(C67-9) Stop Light Switch RED Open : 0V
Close : Battery Voltage Close Condition :
Step on the Brake Pedal
6
(C67-8) Serial ORN/WHT - J1850 Class 2
Communication
7
(C67-7) Serial GRN - J1850 Class 2
Communication
8
(C67-6) Not Used - -
9
(C67-5) Not Used - -
10
(C67-4) G-Sensor Ground BLK 0V
(Less than 0.1V) 4WD Only
DTC C0276, C0285
11
(C67-3) Front Right Wheel Speed Sensor (-) GRY High Level: 1.28~2.2V
Low Level: 0.5~0.86V DTC C0221,C0222,
C0223
12
(C67-2) Front Right Wheel Speed Sensor (+) GRY/RED 12
1.5V DTC C0221,C0222,
C0223
13
(C67-1) Rear Right Wheel Speed Sensor (-) BLK High Level: 1.28~2.28V
Low Level: 0.5~0.86V DTC C0231,C0232,
C0233
Page 334 of 4264
5A-18 BRAKE CONTROL SYSTEM
EHCU Side
Pin No.
(Harness
side
Pin No.) Pin Function Wire
Color Typical Value Note
14
(C67-17) ABS Warning Lamp YEL More than 10V
15
(C67-16) Not Used - -
16
(C67-15) Not Used - -
17
(C67-14) G-Sensor Signal YEL/BLK 2.0~3.0V
(MAX4.0V,MIN1.0V) 4WD Only
It checks in a flat place
(0G:2.5V)
DTC C0276, C0285
18
(C67-13) Front Left Wheel Speed Sensor (+) RED 12
1.5V DTC C0225, C0226,
C0227
19
(C67-12) Rear Right Wheel Speed Sensor (+) ORN 12
1.5V DTC C0231,C0232,
C0233
20
(C67-26) EBD (Brake) Warning Lamp LT BLU More than 10V
21
(C67-25) Starter Switch ON
(Power Supply and Switch Position) BLU/WHT Battery Voltage Control Unit
DTC C0277,C0278
22
(C67-22) Not Used - -
23
(C67-23) Not Used - -
24
(C67-22) Not Used - -
25
(C67-21) Transfer (2-4WD Control Unit) GRY Pulse Signal
(High 4.5V, Low 1.5V) 4WD Only
DTC C0282
26
(C67-20) Front Left Wheel Speed Sensor (-) WHT High Level: 1.28~2.2V
Low Level: 0.5~0.86V DTC C0225, C0226,
C0227
27
(C67-19) Rear Left Wheel Speed Sensor (+) GRY/BLU 12
1.5V
DTC C0235, C0236,
C0237
28
(C67-18) Rear Left Wheel Speed Sensor (-) WHT/BLU High Level: 1.28~2.2V
Low Level: 0.5~0.86V DTC C0235, C0236,
C0237
Page 335 of 4264
BRAKE CONTROL SYSTEM 5A-19
System Components
Electronic Hydraulic Control Unit (EHCU), four Wheel
Speed Sensors, two Warning Lamps, and G-sensor.
Electronic Hydraulic Control Unit (EHCU)
The EHCU consists of ABS control circuits, fault
detector, and a fail-safe. It drives the EHCU according
to the signal from each sensor, cancelling ABS to return
to 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 rear
left side. It consists of a motor, solenoid valves fail safe
relay.
Solenoid Valves: Reduces or holds the caliper fluid
pressure for each front brake or both rear brakes
according to the signal sent from the EHCU.
Buffer chamber: Temporarily holds the brake fluid that
returns from the front and rear brake so that pressure
of front brake can be reduced smoothly.
Motor: Drives the pump according to the signal from
EHCU.
Fail safe Relay: When failure occurs in ABS.
The power supply to solenoid Valve is cut.
ABS Warning Lamp
825L300001
Vehicles equipped with the Anti-lock Brake System
have an amber “ABS” warning lamp in the instrument
panel. The “ABS” warning lamp 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 lamp and disable the anti-lock
braking function.
The “ABS” warning lamp will turn “ON” for
approximately three seconds after the ignition switch is
to the “ON” position.
If the “ABS” warning lamp 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 (WSS)
It consists of a sensor and a rotor. The sensor is
attached to the knuckle on the front wheels and to the
rear wheels.
The rotor is press-fit in the axle shaft.
G-Sensor
The G-sensor 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 and EBD 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.
Page 336 of 4264
5A-20 BRAKE CONTROL SYSTEM
Electronic Brake-force Distribution (EBD) System
ABS has the EBD function. EBD is a function which
controls braking force distribution of a front wheel and a
rear wheel, and makes brake fluid pressure of a rear
wheel the optimal. If the rate of a slip of a rear wheel
becomes large more than fixed compared with a front
wheel about the rate of a slip in order to perform
braking force distribution of a front wheel and a rear
wheel, the brake fluid pressure of a rear wheel will be
controlled. EBD enables it to always utilize the braking
power of a rear wheel for the maximum according to
the load change concerning the back axis by vehicles
loading states (No luggage, loading, etc.), deceleration,
etc. Brake fluid pressure control to a rear wheel is
performed by the EBD function which used the ABS
function without the mechanical proportioning valve.
C05L300016
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
EBD
Electronic Brake-force Distribution
EHCU
Electronic Hydraulic Control Unit
FL
Front Left
FR
Front Right
GEN
Generator
H/U
Hydraulic Unit
MV
Millivolts
RR
Rear
RPS
Revolution per Second
VDC
DC Volts
VAC
AC Volts
W/L
Warning Lamp
WSS
Wheel Speed Sensor
General Diagnosis
General Information
ABS troubles can be classified into two types, those
which can be detected by the ABS warning lamp 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.
5-8840-0366-0 High Impedance Multimeter
When circuit measurements are requested, use a
circuit tester with high impedance.
Page 337 of 4264
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.
Page 342 of 4264
5A-26 BRAKE CONTROL SYSTEM
DATA LIST (Tech 2)
The data displayed by DATA LIST are as follows:
Strings Units Description 2WD 4WD
Front Left Wheel Speed km/h (MPH)
Front Right Wheel Speed km/h (MPH)
Rear Left Wheel Speed km/h (MPH)
Rear Right Wheel Speed km/h (MPH) Start the vehicle and make sure of linear
change in each wheel speed
Brake Switch Open/Closed Brake switch is “closed” when brake pedal is
stepped on.
ABS Warning Lamp On/Off To be “Off” usually
EBD Warning Lamp On/Off To be “Off” usually
ABS Stop State On/Off To be “Off” usually
ABS Relay Active/Inactive To be “Active” usually
Return Pump Active/Inactive To be “Inactive” usually
DTC Status No DTC To be “No DTC” usually
4 Wheel Drive Status Yes/No To be “Yes” usually
-
FL Dump Valve Commanded
(Front Left) Active/Inactive
FL Isolation Valve Commanded
(Front Left) Active/Inactive
FR Dump Valve Commanded
(Front Right) Active/Inactive
FR Isolation Valve Commanded
(Front Right) Active/Inactive
Rear Dump Valve Commanded Active/Inactive
Rear Isolation Valve Commanded Active/Inactive
FL Dump Valve Feedback
(Front Left) Active/Inactive
FL Isolation Valve Feedback
(Front Left) Active/Inactive
FR Dump Valve Feedback
(Front Right) Active/Inactive
FR Isolation Valve Feedback
(Front Right) Active/Inactive
Rear Dump Valve Feedback Active/Inactive
Rear Isolation Valve Feedback Active/InactiveEach valve is “Active” when each valve is
opereted.
G-Sensor Output V 2.0~3.0V when vehicle speed is 0 km/h (flat
place) -
Battery Voltage V The voltage value currently supplied to EHCU
Diagnostics Connector Open/Closed Diagnostics connector is “Open” when
diagnostics connector is connected.