2004 ISUZU TF SERIES brake sensor

FRONT WHEEL DRIVE 4C1-63

13. Wheel Pin
(1) Place hub on a wood workbench or a block of wood,
approx. 6” by 6” to protect the wheel stud ends and threads.
(2) Install wheel stud using a hammer.
Be sure wheel stud is started squarely and seats
completely.

(3) Align index marks and install hub to disc.


14. Bolt
Torque N
m (kgf
m/lb
ft)
103 
10 (10.5 
1/75.9 
7.2)



15. ABS sensor rotor
(1) Set a new ABS sensor rotor, if replacement is required.
(2) Install the ABS sensor rotor in the hub, using special tools.
Installer : 5-8840-2789-0
Grip : 5-8840-0007-0
Refer to the section Brake.


16. Inner Bearing
Outer race ; outer bearing
Install the outer race by driving it into the hub.
Installer : 5-8840-2119-0
(J-36829)
Grip : 5-8840-0007-0
(J-8092)

BRAKE CONTROL SYSTEM 5A-1


SECTION 5A
BRAKE CONTROL SYSTEM
CONTENTS

Service Precaution ............................................................................................................. 5A-4
General Description ........................................................................................................... 5A-5
EHCU, Brake Pipe Diagram .......................................................................................... 5A-6
Hydraulic Unit (H/U)....................................................................................................... 5A-7
Normal Braking ......................................................................................................... 5A-8
Pressure Isolation (Pressure Maintain) .................................................................. 5A-9
Pressure Reduction .................................................................................................. 5A-10
Brake Release ........................................................................................................... 5A-11
Circuit Diagram.............................................................................................................. 5A-12
Connector List ............................................................................................................... 5A-13
Part Location ................................................................................................................. 5A-15
EHCU Pin-outs ............................................................................................................... 5A-17
System Components ..................................................................................................... 5A-19
Electronic Hydraulic Control Unit (EHCU) .............................................................. 5A-19
ABS Warning Lamp .................................................................................................. 5A-19
Wheel Speed Sensor (WSS)..................................................................................... 5A-19
G-Sensor ................................................................................................................... 5A-19
Normal and Anti-lock Braking ................................................................................. 5A-19
Electronic Brake-force Distribution (EBD) System ................................................ 5A-20
Brake Pedal Travel.................................................................................................... 5A-20
Acronyms and Abbreviations ....................................................................................... 5A-20
General Diagnosis ............................................................................................................. 5A-20
General Information ...................................................................................................... 5A-20
ABS Service Precautions.............................................................................................. 5A-20
Computer System Service Precautions....................................................................... 5A-21
General Service Precautions........................................................................................ 5A-21
Note on Intermittents .................................................................................................... 5A-21
Test Driving ABS Complaint Vehicles ......................................................................... 5A-21
"ABS and Brake" Warning Lamp ................................................................................. 5A-22
Normal Operation .......................................................................................................... 5A-22

5A-2 BRAKE CONTROL SYSTEM

Brake (EBD) Warning Lamp.......................................................................................... 5A-22
Tech 2 Scan Tool ........................................................................................................... 5A-23
DATA LIST (Tech 2) ....................................................................................................... 5A-26
Actuator Test (Tech 2)................................................................................................... 5A-27
Diagnostic Trouble Codes................................................................................................. 5A-30
Diagnosis By "ABS" Warning Lamp Illumination Pattern .............................................. 5A-32
Basic Diagnostic Flow Chart ............................................................................................ 5A-35
Basic Inspection Procedure .............................................................................................. 5A-37
1. Basic Inspection of Service Brake ........................................................................... 5A-37
2. Ground Inspection .................................................................................................... 5A-37
Wheel Speed Sensor Inspection Procedure .................................................................... 5A-38
Symptom Diagnosis........................................................................................................... 5A-39
ABS Works Frequently But Vehicle Does Not Decelerate ......................................... 5A-39
Uneven Braking Occurs While ABS Works ................................................................. 5A-40
The Wheels Are Locked ................................................................................................ 5A-40
Brake Pedal Feed Is Abnormal ..................................................................................... 5A-41
Braking Sound (From EHCU) Is Heard
While Not Braking ....................................................................................................... 5A-42
No ABS Warning Lamp ................................................................................................. 5A-43
DTC C0221 (Flash Code 21) Front Right Wheel Speed Sensor
Short Circuit or Circuit Open ......................................................................................... 5A-44
DTC C0222 (Flash Code 22) Front Right Wheel Speed Sensor Incorrect Signal.......... 5A-46
DTC C0223 (Flash Code 23) Front Right Wheel Speed Sensor
Signal - Tooth Chipping................................................................................................... 5A-48
DTC C0225 (Flash Code 25) Front Left Wheel Speed Sensor Short Circuit or
Circuit Open .................................................................................................................... 5A-50
DTC C0226 (Flash Code 26) Front Left Wheel Speed Sensor Incorrect Signal ............ 5A-52
DTC C0227 (Flash Code 27) Front Left Wheel Speed Sensor Signal - Tooth
Chipping ........................................................................................................................... 5A-54
DTC C0231 (Flash Code 31) Rear Right Wheel Speed Sensor Short Circuit or
Circuit Open .................................................................................................................... 5A-56
DTC C0232 (Flash Code 32) Rear Right Wheel Speed Sensor Incorrect Signal ........... 5A-58
DTC C0233 (Flash Code 33) Rear Right Wheel Speed Sensor Signal - Tooth
Chipping ........................................................................................................................... 5A-60

BRAKE CONTROL SYSTEM 5A-3

DTC C0235 (Flash Code 35) Rear Left Wheel Speed Sensor Short Circuit or
Circuit Open .................................................................................................................... 5A-62
DTC C0236 (Flash Code 36) Rear Left Wheel Speed Sensor Incorrect Signal ............. 5A-64
DTC C0237 (Flash Code 37) Rear Left Wheel Speed Sensor Signal - Tooth
Chipping ........................................................................................................................... 5A-66
DTC C0238 (Flash Code 38) Tire Diameter Error ............................................................. 5A-68
DTC C0241 (Flash Code 41) Front Right Isolation Solenoid Circuit Open or
Shorted to Ground ........................................................................................................... 5A-69
DTC C0242 (Flash Code 42) Front Right Dump Solenoid Circuit Open or Shorted
to Ground.......................................................................................................................... 5A-69
DTC C0243 (Flash Code 43) Front Right Isolation Solenoid Circuit Shorted to
Battery............................................................................................................................... 5A-69
DTC C0244 (Flash Code 44) Front Right Dump Solenoid Circuit Shorted to
Battery............................................................................................................................... 5A-69
DTC C0245 (Flash Code 45) Front Left Isolation Solenoid Circuit Open or
Shorted to Ground ........................................................................................................... 5A-71
DTC C0246 (Flash Code 46) Front Left Dump Solenoid Circuit Open or Shorted
to Ground.......................................................................................................................... 5A-71
DTC C0247 (Flash Code 47) Front Left Isolation Solenoid Circuit Shorted to
Battery............................................................................................................................... 5A-71
DTC C0248 (Flash Code 48) Front Left Dump Solenoid Circuit Shorted to
Battery............................................................................................................................... 5A-71
DTC C0251 (Flash Code 51) Rear Isolation Solenoid Circuit Open or Shorted to
Ground .............................................................................................................................. 5A-73
DTC C0252 (Flash Code 52) Rear Dump Solenoid Circuit Open or Shorted to
Ground .............................................................................................................................. 5A-73
DTC C0253 (Flash Code 53) Rear Isolation Solenoid Circuit Shorted to Battery ......... 5A-73
DTC C0254 (Flash Code 54) Rear Dump Solenoid Circuit Shorted to Battery .............. 5A-73
DTC C0265 (Flash Code 65) Fail Safe Relay (FSR) Shorted to Ground ......................... 5A-75
DTC C0266 (Flash Code 66) Fail Safe Relay (FSR) Shorted to Battery.......................... 5A-75
DTC C0267 (Flash Code 67) ABS Motor Shorted to Ground .......................................... 5A-77
DTC C0268 (Flash Code 68) ABS Motor Shorted to Battery ........................................... 5A-77
DTC C0271 (Flash Code 71) ECU Failure or Valve +B Circuit Open .............................. 5A-79
DTC C0274 (Flash Code 74) ABS Operation Long Time ................................................. 5A-80
DTC C0276 (Flash Code 76) G-Sensor Malfunction ........................................................ 5A-82

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.

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)

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

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