1998 ISUZU TROOPER warning

DRIVE LINE CONTROL SYSTEM (TOD) 4B2±86
Diagnosis from Symptom
Troubles that are not indicated by the warning lamp are
listed in the table below. These troubles are caused by
the faults that cannot be detected by the self-diagnostic
function of the control unit.
If this type of trouble is observed, interview the customer
and conduct test runs to reproduce the trouble,cross-check the reported trouble with the listed
phenomena, and diagnose and analyze the trouble on the
item by item basis.
PhenomenaMajor causeCorrective action
1The tight corner braking is ob-
served when the vehicle is subject
to full steering.
The standard tires are not used.

The tire pressure is incorrect.

The tires are worn inuniformity.

The transfer or wiring is
imperfect.

The limited slip differential is
failed.Check and recondition the ve-
hicle according to Chart 1.
2Even if the 4WD SW is select to the
4WD position, the 4WD mode is not
active, resulting in remarkable rear
wheel spin.
The transfer or wiring is
imperfect.

The shift on the fly system is
failed.Check and recondition the ve-
hicle according to Chart 2.
3
When the 4WD SW is select to
the 4WD position, the drive
resistance of the 4WD system is
too large to get sufficient running
speed.

Noised drive line.
The standard tires are not used.

The tire pressure is incorrect.

The tires are worn inuniformity.

The transfer or wiring is
imperfect.

The limited slip differential is Check and recondition the ve-
hicle according to Chart 1.
4The shift on the fly system (front
axle) generates gear noises.
The wiring is imperfect.

The full automatic free wheel
hub is failed.Check and recondition the ve-
hicle according to Chart 3.
5The braking distance gets long
even when the ABS is active.
The wiring is imperfect.

The ABS is failed.Check and recondition the ve-
hicle according to Chart 4.

4C±2
DRIVE SHAFT SYSTEM
Service Precaution
WARNING: I F S O E Q U IPPED 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.
General Description
This publication contains essential removal, installation,
adjustment and maintenance procedures.
The front axle utilizes a central disconnect type front
axle/transfer case system.
The drive axles are completely flexible assemblies,
consisting of inner and outer constant velocity (CV) drive
shaft joints connected by an axle shaft.
For description of propeller shaft and universal joint, refer
to Front/Rear Propeller Shaft in this section.

TRANSFER CASE (STANDARD TYPE)
4D1±1
DRIVELINE/AXLE
TRANSFER CASE (STANDARD TYPE)
CONTENTS
Service Precaution 4D1±1. . . . . . . . . . . . . . . . . . . . . .
General Description 4D1±2. . . . . . . . . . . . . . . . . . . . .
Transfer Rear Oil Seal 4D1±8. . . . . . . . . . . . . . . . . . .
Removal 4D1±8. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 4D1±8. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Transfer Case Assembly 4D1±9. . . . . . . . . . . . . . . . .
Removal 4D1±9. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 4D1±10. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Transfer Rear Cover Assembly
(4WD Switch Model) 4D1±11. . . . . . . . . . . . . . . . . . . .
Transfer Rear Cover Assembly and
Associated Parts 4D1±11. . . . . . . . . . . . . . . . . . . . . .
Removal 4D1±12. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 4D1±13. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Disassembly 4D1±16. . . . . . . . . . . . . . . . . . . . . . . . . .
Inspection and Repair 4D1±17. . . . . . . . . . . . . . . . . .
Reassembly 4D1±17. . . . . . . . . . . . . . . . . . . . . . . . . .
Transfer Rear Cover Assembly
(Except 4WD Switch Model) 4D1±19. . . . . . . . . . . . . . Transfer Rear Cover Assembly and
Associated Parts 4D1±19. . . . . . . . . . . . . . . . . . . . . .
Removal 4D1±20. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 4D1±20. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Disassembly 4D1±23. . . . . . . . . . . . . . . . . . . . . . . . . .
Inspection and Repair 4D1±24. . . . . . . . . . . . . . . . . .
Reassembly 4D1±24. . . . . . . . . . . . . . . . . . . . . . . . . .
Detent, Shift Arm, and Interlock Pin 4D1±26. . . . . . . .
Disassembled View 4D1±26. . . . . . . . . . . . . . . . . . . .
Disassembly 4D1±26. . . . . . . . . . . . . . . . . . . . . . . . . .
Inspection and Repair 4D1±28. . . . . . . . . . . . . . . . . .
Reassembly 4D1±28. . . . . . . . . . . . . . . . . . . . . . . . . .
Transfer Case Assembly 4D1±30. . . . . . . . . . . . . . . . .
Disassembled View 4D1±30. . . . . . . . . . . . . . . . . . . .
Disassembly 4D1±31. . . . . . . . . . . . . . . . . . . . . . . . . .
Inspection and Repair 4D1±33. . . . . . . . . . . . . . . . . .
Reassembly 4D1±37. . . . . . . . . . . . . . . . . . . . . . . . . .
Main Data and Specifications 4D1±43. . . . . . . . . . . . .
Special Tools 4D1±46. . . . . . . . . . . . . . . . . . . . . . . . . . .
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.

4D2±1 TRANSFER CASE (TOD)
DRIVELINE/AXLE
TRANSFER CASE (TOD)
CONTENTS
Service Precaution 4D2±1. . . . . . . . . . . . . . . . . . . . . .
Transfer Case Assembly 4D2±2. . . . . . . . . . . . . . . . .
Removal 4D2±2. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 4D2±3. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Transfer Rear Oil Seal 4D2±5. . . . . . . . . . . . . . . . . . .
Transfer Rear Oil Seal and Associated
Parts 4D2±5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Removal 4D2±5. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 4D2±5. . . . . . . . . . . . . . . . . . . . . . . . . . . .
TOD ECU 4D2±7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Removal 4D2±7. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 4D2±7. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Unit Repair 4D2±8. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Inspection 4D2±8. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Transfer Case 4D2±9. . . . . . . . . . . . . . . . . . . . . . . . . .
Disassembled View 4D2±9. . . . . . . . . . . . . . . . . . . .
Disassembly 4D2±9. . . . . . . . . . . . . . . . . . . . . . . . . .
Reassembly 4D2±10. . . . . . . . . . . . . . . . . . . . . . . . . .
Transfer Cover Assembly 4D2±12. . . . . . . . . . . . . . . .
Disassembled View 4D2±12. . . . . . . . . . . . . . . . . . . .
Disassembly 4D2±12. . . . . . . . . . . . . . . . . . . . . . . . . .
Reassembly 4D2±14. . . . . . . . . . . . . . . . . . . . . . . . . .
Transfer Case Assembly Clutch Pack and
Clutch Cam 4D2±16. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Disassembled View 4D2±16. . . . . . . . . . . . . . . . . . . . Disassembly 4D2±16. . . . . . . . . . . . . . . . . . . . . . . . . .
Sprocket and Mechanical Lock 4D2±18. . . . . . . . . . . .
Disassembled View 4D2±18. . . . . . . . . . . . . . . . . . . .
Disassembly 4D2±18. . . . . . . . . . . . . . . . . . . . . . . . . .
Output Shafts and Shift Control Shaft 4D2±20. . . . . .
Disassembled View 4D2±20. . . . . . . . . . . . . . . . . . . .
Disassembly 4D2±21. . . . . . . . . . . . . . . . . . . . . . . . . .
Transfer Case 4D2±23. . . . . . . . . . . . . . . . . . . . . . . . . .
Disassembled View 4D2±23. . . . . . . . . . . . . . . . . . . .
Disassembly 4D2±24. . . . . . . . . . . . . . . . . . . . . . . . . .
Inspection and Repair 4D2±26. . . . . . . . . . . . . . . . . .
Transfer Case 4D2±30. . . . . . . . . . . . . . . . . . . . . . . . . .
Disassembled View 4D2±30. . . . . . . . . . . . . . . . . . . .
Reassembly 4D2±30. . . . . . . . . . . . . . . . . . . . . . . . . .
Output Shafts and Shift Control Shaft 4D2±34. . . . . .
Disassembled View 4D2±34. . . . . . . . . . . . . . . . . . . .
Reassembly 4D2±34. . . . . . . . . . . . . . . . . . . . . . . . . .
Sprocket and Mechanical Lock 4D2±37. . . . . . . . . . . .
Disassembled View 4D2±37. . . . . . . . . . . . . . . . . . . .
Reassembly 4D2±37. . . . . . . . . . . . . . . . . . . . . . . . . .
Clutch Pack and Clutch Cam 4D2±39. . . . . . . . . . . . .
Disassembled View 4D2±39. . . . . . . . . . . . . . . . . . . .
Reassembly 4D2±39. . . . . . . . . . . . . . . . . . . . . . . . . .
Main Data and Specifications 4D2±41. . . . . . . . . . . . .
Special Tools 4D2±43. . . . . . . . . . . . . . . . . . . . . . . . . . .
Service Precaution
WARNING: I F S O E Q U IPPED 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.

5A±1 BRAKE CONTROL SYSTEM
BRAKES
CONTENTS
Brake Control System 5A. . . . . . . . . . . . . . . . . . . .
Anti±lock Brake System 5B. . . . . . . . . . . . . . . . . . Power±Assisted Brake System 5C. . . . . . . . . . . .
Parking Brakes 5D. . . . . . . . . . . . . . . . . . . . . . . . .
BRAKE CONTROL SYSTEM
CONTENTS
Service Precaution 5A±2. . . . . . . . . . . . . . . . . . . . . .
General Description 5A±3. . . . . . . . . . . . . . . . . . . . .
System Components 5A±3. . . . . . . . . . . . . . . . . . .
Electronic Hydraulic Control Unit (EHCU) 5A±3.
ABS Warning Light 5A±4. . . . . . . . . . . . . . . . . . . .
Wheel Speed Sensor 5A±4. . . . . . . . . . . . . . . . . .
G-Sensor 5A±4. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Normal and Anti-lock Braking 5A±4. . . . . . . . . . .
Brake Pedal Travel 5A±4. . . . . . . . . . . . . . . . . . . .
Acronyms and Abbreviations 5A±4. . . . . . . . . . . .
General Diagnosis 5A±5. . . . . . . . . . . . . . . . . . . . . . .
General Information 5A±5. . . . . . . . . . . . . . . . . . . .
ABS Service Precautions 5A±5. . . . . . . . . . . . . . .
Computer System Service Precautions 5A±5. . .
General Service Precautions 5A±5. . . . . . . . . . . .
Note on Intermittents 5A±5. . . . . . . . . . . . . . . . . . .
Test Driving ABS Complaint Vehicles 5A±6. . . . .
ªABSº Warning Light 5A±6. . . . . . . . . . . . . . . . . . .
Normal Operation 5A±6. . . . . . . . . . . . . . . . . . . . .
Basic Diagnostic Flow Chart 5A±6. . . . . . . . . . . .
Basic Inspection Procedure 5A±7. . . . . . . . . . . . .
Tech 2 Scan Tool 5A±8. . . . . . . . . . . . . . . . . . . . . .
Getting Started 5A±9. . . . . . . . . . . . . . . . . . . . . . . .
Operating Procedure 5A±10. . . . . . . . . . . . . . . . . . .
Data List 5A±11. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
EHCU Connector Pin-out Checks 5A±12. . . . . . . .
Circuit Diagram (LHD model / 6VD1 and
4JG2) 5A±13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Circuit Diagram (LHD model / 4JG2) 5A±14. . . . .
Circuit Diagram (LHD model / 4JG2) 5A±15. . . . .
Circuit Diagram (LHD model / 6VD1) 5A±16. . . . .
Circuit Diagram (LHD model / 6VD1) 5A±17. . . . .
Connector List (LHD model) 5A±18. . . . . . . . . . . .
Part Location (LHD model) 5A±20. . . . . . . . . . . . . .
Circuit Diagram (RHD model / 6VD1 and
4JG2) 5A±21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Circuit Diagram (RHD model / 4JG2) 5A±22. . . . .
Circuit Diagram (RHD model / 4JG2) 5A±23. . . . .
Circuit Diagram (RHD model / 6VD1) 5A±24. . . . .
Circuit Diagram (RHD model / 6VD1) 5A±25. . . . .
Circuit Diagram (RHD model / 6VE1 and
4JX1) 5A±26. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Circuit Diagram (RHD model / 4JX1) 5A±27. . . . .
Circuit Diagram (RHD model / 4JX1) 5A±28. . . . .
Circuit Diagram (RHD model / 6VE1) 5A±29. . . . .
Circuit Diagram (RHD model / 6VE1) 5A±30. . . . .
Connector List (RHD model) 5A±31. . . . . . . . . . . .
Part Location (RHD model) 5A±34. . . . . . . . . . . . .
Symptom Diagnosis 5A±35. . . . . . . . . . . . . . . . . . . . .
Chart A±1 ABS Works Frequently But
Vehicle Does Not Decelerate 5A±35. . . . . . . . . . .
Chart TA-1 ABS Works Frequently But
Vehicle Does Not Decelerate (Use
TECH 2) 5A±36. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chart A-2 Uneven Braking Occurs While
ABS Works 5A±36. . . . . . . . . . . . . . . . . . . . . . . . . . .
Chart A-3, TA-3 The Wheels Are Locked 5A±36.
Chart A-4 Brake Pedal Feed Is Abnormal 5A±37.
Chart A-5, TA-5 Braking Sound (From
EHCU) Is Heard While Not Braking 5A±38. . . . . .
Diagnostic Trouble Codes 5A±39. . . . . . . . . . . . . . . .
Diagnosis By ªABSº Warning Light
Illumination Pattern 5A±40. . . . . . . . . . . . . . . . . . . . .
Diagnostic Trouble Codes (DTCs) 5A±40. . . . . . .
Chart B-1 With the key in the ON position
(Before starting the engine). Warning light
(W/L) is not activated. 5A±43. . . . . . . . . . . . . . . . .
Chart B-2 EHCU Abnormality (DTC 14) 5A±43. . .
Chart B-3 Power Voltage Drop (DTC 15) 5A±44. .
Chart B-4 CLASS-2 Communication Line
Abnormality (DTC 16) 5A±44. . . . . . . . . . . . . . . . .
Chart B-5 G-Sensor Circuit (DTC 21) 5A±45. . . . .
Chart B-6 Abnormal Transmission Input
(DTC 23) 5A±46. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chart B-7 Transfer Monitor (DTC 24) 5A±47. . . . .
Chart B-8 EHCU Pump Motor And Motor
Relay Circuit (DTC 32) 5A±47. . . . . . . . . . . . . . . . .
Chart B-9 EHCU Pump Valve And Valve
Relay Circuit (DTC 35) 5A±47. . . . . . . . . . . . . . . . .
Chart B-10 FL Isolation Solenoid Valve
Abnormality (DTC 41) 5A±48. . . . . . . . . . . . . . . . .
Chart B-11 FL Dump Solenoid Valve
Abnormality (DTC 42) 5A±48. . . . . . . . . . . . . . . . .
Chart B-12 FR Isolation Solenoid Valve
Abnormality (DTC 43) 5A±48. . . . . . . . . . . . . . . . .
Chart B-13 FR Dump Solenoid Valve
Abnormality (DTC 44) 5A±49. . . . . . . . . . . . . . . . .
Chart B-14 Rear Isolation Solenoid Valve
Abnormality (DTC 45) 5A±49. . . . . . . . . . . . . . . . .
Chart B-15 Rear Dump Solenoid Valve
Abnormality (DTC 46) 5A±49. . . . . . . . . . . . . . . . .

5A±2
BRAKE CONTROL SYSTEM
Chart B-16 FL Speed Sensor Disconnection
(DTC 51) 5A±50. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chart B-17 FR Speed Sensor Disconnection
(DTC 52) 5A±50. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chart B-18 RL Speed Sensor Disconnection
(DTC 53) 5A±51. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chart B-19 RR Speed Sensor Disconnection
(DTC 54) 5A±51. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chart B-20 FL Speed Sensor Short Circuit
(DTC 61) 5A±52. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chart B-21 FR Speed Sensor Short Circuit
(DTC 62) 5A±53. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chart B-22 RL Speed Sensor Short Circuit
(DTC 63) 5A±54. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chart B-23 RR Speed Sensor Short Circuit
(DTC 64) 5A±55. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chart B-24 Sensor Signal Input Abnormality
(DTC 65) 5A±56. . . . . . . . . . . . . . . . . . . . . . . . . . . . Sensor Signal Abnormality Criteria using
TECH 2 5A±56. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Unit Inspection Procedure 5A±57. . . . . . . . . . . . . . . .
Chart C-1-1 FL Sensor Output Inspection
Procedure 5A±57. . . . . . . . . . . . . . . . . . . . . . . . . . .
Chart C-1-2 FR Sensor Output Inspection
Procedure 5A±58. . . . . . . . . . . . . . . . . . . . . . . . . . .
Chart C-1-3 RL Sensor Output Inspection
Procedure 5A±58. . . . . . . . . . . . . . . . . . . . . . . . . . .
Chart C-1-4 RR Sensor Output Inspection
Procedure 5A±59. . . . . . . . . . . . . . . . . . . . . . . . . . .
Chart TC-1 Sensor Output Inspection
Procedure (Use TECH 2) 5A±59. . . . . . . . . . . . . .
Chart C-2 Transmission Input Inspection
Procedure 5A±60. . . . . . . . . . . . . . . . . . . . . . . . . . .
Chart TC-2 Transmission Input Inspection
Procedure (Use TECH 2) 5A±61. . . . . . . . . . . . . .
Special Tools 5A±62. . . . . . . . . . . . . . . . . . . . . . . . . . .
Service Precaution
WARNING: I F S O E Q U IPPED 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.

5A±3 BRAKE CONTROL SYSTEM
General Description
The Anti-lock Brake System (ABS) works on all four
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.
C05RW027
Legend
(1) With P&B Valve Model
(2) With LSPV Model
(3) Electronic Hydraulic Control Unit (EHCU)
(4) Front Wheel Speed Sensor
(5) Rear Wheel Speed Sensor(6) G-Sensor
(7) Proportioning and Bypass (P&B) Valve
(8) Load Sensing Proportioning Valve (LSPV)
(9) Electronic Line
(10) Hydraulic Line
System Components
Electronic Hydraulic Control Unit (EHCU), four Wheel
Speed Sensors, Warning Light, and G-sensor.
Electronic Hydraulic Control Unit (EHCU)
The EHCU consists of ABS control circuits, fault detector,
and a fail-safe. It drives the hydraulic unit according to the
signal from each sensor, cancelling ABS to return to

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 ªABSº warning light in the instrument panel.
The ªABSº 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 ªONº the ªABSº warning
light and disable the Anti-lock braking function.
The ªABSº light will turn ªONº for approximately three
seconds after the ignition switch is to the ªONº position.
If the ªABSº light stays ªONº after the ignition switch is the
ªONº position, or comes ªONº and stays ªONº 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 ªsine curveº 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 ªbumpº 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