warning light ISUZU TF SERIES 2004 Workshop Manual

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.

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.

BRAKE CONTROL SYSTEM 5A-27

Actuator Test (Tech 2)
There are 5 different menus available for this test. The
state of each circuit can be tested by using these
menus. Especially when DTC cannot be detected, a
faulty circuit can be diagnosed by testing each circuit by
means of these menus.
Even when DTC has been detected, the circuit tests
using these menus could help discriminate between a
mechanical trouble and an electrical trouble.
In all cases test condition; Engine stops with the key
turned to the “ON” position. To be more specific, the
test is conducted with the brake pedal stepped on after
stepping once and releasing.
 Engine: Stop
 Ignition SW: ON

060L300002

ABS Check Light Test
Test condition: Engine stops with the key turned to the
“ON” position. To be more specific, the test is
conducted with the brake pedal stepped on after
stepping once and releasing.
 The circuit is normal if the warning light (lamp) in
the meter panel comes on and goes out in
accordance with Tech2’s instruction.

060L300002

Return Pump Test
Test condition: Engine stops with the key turned to the
“ON” position. To be more specific, the test is
conducted with the brake pedal stepped on after
stepping once and releasing.
Make sure of the working sound of the return pump
relay and return pump.
The circuit is normal if the working sound of the return
pump relay and return pump are made in accordance
with Tech2’s instruction.

060L300002

5A-32 BRAKE CONTROL SYSTEM

Diagnosis By “ABS” Warning Lamp
Illumination Pattern
In the event that there is abnormality in the “ABS”
warning Lamp illumination pattern while the key is in the
ON position or if the warning Lamp is actuated during
driving, trouble should be diagnosed on a illumination
pattern basis as follows:

No. Condition “ABS” Warning Lamp Illumination Pattern Diagnostic
1 Warning Lamp is
actuated normally
Normal
2 Warning Lamp is not
lit
Warning Lamp lighting circuit
trouble. Go to No ABS
Warning Lamp.
3 Warning Lamp
remains ON
Diagnostic trouble codes are
stored.
Display diagnostic trouble
codes and diagnose on a
code basis according to
the flow charts.
4 Warning Lamp is
actuated while driving
Diagnostic trouble codes are
stored.
Display diagnostic trouble
codes and diagnose on a
code basis according to
the flow charts.

Diagnostic Trouble Codes (DTCs)
When the warning lamp in the meter remains ON, the
EHCU stores the fault identification and disables the
ABS.

PARKING BRAKE SYSTEM 5D-1

SECTION 5D
BRAKES
PARKING BRAKE SYSTEM
CONTENTS

Service Precaution .......................................... 5D-1
Service Precaution ....................................... 5D-1
General Description ...................................... 5D-1
Parking Brake Lever ........................................ 5D-2
Parking Brake Lever Assembly and
Associated Parts (Bench Seat) .................. 5D-2
Removal ....................................................... 5D-3
Installation............................................................
5D-3
Front Parking Brake Cable....................................
5D-5
Front Parking Brake Cable and Associated
Parts (Bench Seat).........................................
5D-5
Removal...............................................................
5D-6
Installation............................................................
5D-6
Parking Brake Lever...............................................
5D-8
Parking Brake Lever Assembly and Associated
Parts (Buckle Seat)....................................... 5D-8
Removal ....................................................... 5D-8
Installation .................................................... 5D-8
Parking Brake Rear Cable ............................... 5D-9
Parking Brake Rear Cable and Associated
Parts ............................................................ 5D-9
Removal ....................................................... 5D-10
Installation .................................................... 5D-10
Inspection and Repair ................................... 5D-11
Parking Brake Adjustment ............................ 5D-11
Main Data and Specifications........................... 5D-12
Troubleshooting ............................................ 5D-13


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, REFE
R
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, o
r
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
Pulling up the parking brake lever by hand will set the
parking brake. By means of a ratchet type lock, the
lever can be held in that position until it is released. The
position of the lever is transmitted through cable/leve
r
systems to the rear wheels. These parts are designed
to obtain sufficient braking force even when parking on
slopes. When the parking brake is set, or when the
ignition SW is in the "ON" position, the brake warning
light illuminates. The rear wheel parking brake is a
leading-trailing brake (mechanical inside expansion
type) built in the rear drum brake. Parking brake
adjustment is made through the adjusting hole (bored
through back plate). Parking brake lever stroke should
be adjusted to 8

14 notches with 30kg (bench seat) o
r
6

8 notches with 30kg (bucket seat). Refer to “Parking
Brake Adjustment" in this section.

8A-2 ELECTRICAL-BODY AND CHASSIS
PAGE
Fuse and Slow Blow Fuse Location (Relay and Fuse Box) .................................... 8A- 31
Fuse Location ............................................................................................................. 8A- 33
Diode Location ........................................................................................................... 8A- 34
Fuse Block Circuit ...................................................................................................... 8A- 35
Fuse Block Circuit (C24SE) ....................................................................................... 8A- 35
Fuse Block Circuit (6VE1) ......................................................................................... 8A- 37
Fuse Block Circuit (4JA1-TC/4JH1-TC) - RHD ......................................................... 8A- 39
Fuse Block Circuit (4JA1-TC/4JH1-TC) – LHD ......................................................... 8A- 41
Fuse Block Circuit (4JH1-L) ...................................................................................... 8A- 43
Grounding Point ............................................................................................................. 8A- 45
Ground Point .............................................................................................................. 8A- 45
Ground Point Location .............................................................................................. 8A- 61
Main Cable harness Routing .......................................................................................... 8A- 63
C24SE / 6VE1 / 4JA1-L / 4JH1-TC .............................................................................. 8A- 63
Instrument Harness .................................................................................................... 8A- 71
System Repair .................................................................................................................8A- 73
Start and Charging ..................................................................................................... 8A- 73
Engine Control Module (ECM) ................................................................................... 8A- 89
Exhaust Gas Recalculation (EGR): 4JA1-L Only ...................................................... 8A- 109
Lighting ....................................................................................................................... 8A- 114
Front Fog Light ........................................................................................................... 8A- 136
Rear Fog Light ............................................................................................................ 8A- 144
Head Light Leveling ................................................................................................... 8A- 149
Illumination ................................................................................................................. 8A- 154
Hazard Warning Flasher, Turn Signal Light, Back Up Light,
Horn and Stop Light ................................................................................................. 8A- 161
Dome Light, Spot Light and Warning Buzzer .......................................................... 8A- 181
Windshield Wiper and Washer .................................................................................. 8A- 196
Transmission Control Module (TCM) ....................................................................... 8A- 214
Meter, Warning Light and Indicator Light ................................................................ 8A- 223
Heater and Air Conditioning ...................................................................................... 8A- 281
Power Door Lock ....................................................................................................... 8A- 293

ELECTRICAL-BODY AND CHASSIS 8A-25
Light Name Rated Power
V-W Number of
Bulbs Lens
Color Remarks
W/O Tacho 5Illumination light 14-2
W/ Tacho 7White
Turn Signal 14-1.12 2 Green
High Beam 14-1.12 1 Blue
Low Fuel 14-1.12 1 Amber
A/T Oil Temp 14-1.12 1 Red
Brake system 14-1.12 1 Red
4WD 14-1.12 1 Green
Seat belt 14-1.12 1 Red
Oil pressure 14-1.12 1 Red
ABS 14-1.12 1 Amber
SEDIMENTER 14-1.12 1 Red
AIR BAG 14-1.12 1 Red
Brake 14-1.12 1 Red
Charge 14-1.12 1 Red
Check Trans 14-1.12 1 Red
Check 4WD 14-1.12 1 Red
Power drive 14-1.12 1 Amber
3rd start 14-1.12 1 Green
4L 14-1.12 1 Green
Cruise Set 14-1.12 1 Green
Check Engine 14-1.12 1 Amber
Front Fog 14-1.12 1 Green
Rear foglight 14-1. 12 1 Amber
Glow 14-1.12 1 Amber
P LED 1 Green
R LED 1 Green
N LED 1 Green
D LED 1 Green
3 LED 1 Green
2 LED 1 Green












Indicator/
Warning
light
A/T shift
indicator
L LED 1 Green

ELECTRICAL-BODY AND CHASSIS 8A-161
HAZARD WARNING FLASHER, TURN SIGNAL LIGHT, BACK UP
LIGHT, HORN AND STOP LIGHT
PARTS LOCATION (RHD)






RTW48AXF016601 & RTW48AXF016701

8A-168 ELECTRICAL-BODY AND CHASSIS
TURN SIGNAL LIGHT AND HAZARD WARNING LIGHT
1. Turn signal light does not light on both sides (RH and LH)

Checkpoint Trouble Cause Countermeasure



Replace the flasher unit

Flasher unit malfunction
NG

Repair or replace the
combination switch
Turn signal switch continuity
between connector
5
B-60 - 6 B-60 and
5
B-60 - 7 B-60 when
turn signal switch operates
Short circuit between
connector 3
B-61 - 1 B-61
when turn signal switch
operates with starter switch
in “ON” position (Turn
signal light should be ON)

Poor switch point contact or
faulty switch
NG OK

Reinstall or replace fuse No.
EB-16 (10A)

Fuse No. EB-16 (10A, Fuse
box)

Poor fuse contact or blown
fuse
NG
OK OK

Repair open circuit or
connector contact
Continuity between
connector 2
B-61 -ground
(Should be continuity)


Open circuit or poor connector
contact
NG

ELECTRICAL-BODY AND CHASSIS 8A-169
2. Turn signal light does not light on one side (RH or LH)

Checkpoint Trouble Cause Countermeasure



Repair open circuit or
connector contact

Open circuit or poor connector
contact
NG
(LH)
Continuity between
3
C-25 - 6 B-60 (FRT),
1
C-35 - 6 B-60 (SIDE)
1
F-6 - 6 B-60 (RR)
(RH)
Continuity between
3
C-18 - 7 B-60 (FRT),
1
C-1 - 7 B-60 (SIDE)
1
F-5 - 7 B-60 (RR)

Repair or replace the
combination switch

Turn signal switch continuity

Poor switch point contact or
faulty switch
NG
OK OK

Repair open circuit or
connector contact

Open circuit or poor connector
contact
NG



3. Hazard warning light does not light



Repair or replace the hazard
SW.

Hazard SW. malfunction
NG
Voltage between 5 B-16 -
ground (Should be battery
voltage present)

Hazard SW. continuity


Reinstall or replace the fuse
No. EB-16 (10A)

Fuse No. EB-16 (10A, Relay
and fuse box)

Poor fuse contact or blown
fuse
NG
OK OK

Repair open circuit or
connector contact
Open circuit or poor
connector contact between
fuse No. EB-16 (10A) -
5
B-16 NG



4. Flashing rate too fast (One side)

Replace the bulb or repair
open circuitInspect bulbBurned out bulb NG