oil ISUZU TROOPER 1995 Workshop Manual

5A4-4 4-WHEEL ANTILOCK BRAKE SYSTEM (ABS)
ABS WARNING LIGHT
Vehicles equipped with the Antilock Brake System
have an
amber "ABS" warning light in the
instrument panel. The "ABS" warning light will
illuminate if a malfunction in the Antilock Brake
System is detected by the Electronic Brake
Control
Module (EBCM). In case of an electronic
malfunction, the EBCM will turn "ON" the "ABS"
warning light and disable the Antilock braking
function.
The
"ABS" light 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.
If the "ABS" light stays "ON" after engine start-up,
or comes "ON" and stays "ON" while driving, the
Antilock Brake System should be inspected
for a
malfunction according to the diagnosis procedure.
Fig. 5A4-2
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
"sine curve" 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 EBCM. It is normally on, and is turned
off when the vehicle deceleration speed exceeds
about 0.35G.
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
EBCM's operating system to ensure ABS control.
NORMAL AND ANTILOCK BRAKING
Under normal driving conditions, the Antilock 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 antilock function or until the vehicle is
stopped. A
slight ticking or popping noise may be
heard
during brake applications when the Antilock
features is being used.
When the
Antilock 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 Antilock 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.
ABBREVIATIONS
Several abbreviations are commonly used
throughout this section:
ABS .......................................... Antilock Brake System
CKT ...................................................................... Circuit
DLC ............................................... Data Link Connector
EBCM ....................... Eiectronic Brake Control Module
FL. ................................................................... Front Left
FR ................................................................. Front Right
GEN ............................................................... Generator
HU .......................................................... Hydraulic Unit
MV ................................................................... Millivolts
RL .................................................................... Rear Left
RR ................................................................. Rear Right
RPS .......................................... Revolution per Second
UVR ............................................................. Valve Relay
VDC .................................................................. DC Volts
VAC .................................................................. AC Volts
W/L .........................................................
Warning Light
WSS ............................................ Wheel Speed Sensor

5A4-22 4-WHEEL ANTI LOCK BRAKE SYSTEM (ABS)
(j): Pump Motor Relay Test
The pump motor operates when current flows through the pump motor relay coil (Fig. 5A4-9).
PUMP
MOTOR
~ II
....----
EBCM ~ .____
MOTOR RELAY
Fig. 5A4-9
Confirm the operation of the pump motor by its operating sound in the engine compartment.
TECH 1 Display Key Operation
Display 1 Is the pump motor working ? If so, press the YES key. If not, press the NO
key. (The pump motor works for about 5 seconds.)
P.MOTOR RELAY
COMMANDED ON * If the YES key is pressed, the menu display will be returned.
OKAY ?
(YES/NO)
If the NO key was pressed above
Display 2
A test failure.
The pump motor has mechanical trouble.
P.MOTOR RELAY
TEST FAILED * If the YES key is pressed, the menu display will be returned.
(YES)
If the YES or NO key was not pressed within 5 sec. on Display 1 above
Display 3
Did the pump motor work normally?
If so, press the YES key. If not, press the NO key.
P.MOTOR RELAY
OKAY ? * YES key c:::> Menu display
(YES/NO) *No key c:::>Display 2
•

4-WHEEL ANTILOCK BRAKE SYSTEM (ABS) 5A4-23
BRAKE
SYSTEM TEST (®, @, and @)
When conducting these tests, jack up the vehicle. Be sure to confirm that the brakes work normally.
Place transmission
in Neutral.
\V CAUTION: When testing the valves successively, leave time intervals of 10min. or more between tests so as to
protect the valves.
The operating conditions
of solenoid valve and resulting brake effect change during the test:
Test
Steps
1) Confirmation of no brake effect (Can the wheel(s) be turned by hand when the brake pedal is
released?).
2) Confirmation of brake effect (Can the wheel(s) be locked when the brake pedal is depressed?)
3) Brake oil pressure is reduced and held at that level.
4) Can the wheel(s) be turned by hand?
5) Solenoid valve is released so that brake pedal pressure reaches brake. Is the wheel(s) locked?
(2) (5)
I
(3)
(1) (4) I
I
..,. ;.,.. lncrea~e ..,.1.,.. Reduce I Increase ... : ... 1 -Retam 1 -Retain I -Retain I I I
I I I
I I I
I I I
ON
Brake
pedal OFF
Reduce
r
Retain
I Solenoid valve
Pump
motor ~

4-WHEEL ANTILOCK BRAKE SYSTEM (ABS) 5A4-49
2. Diagnostic trouble codes:
Choose and trace an appropriate flowchart by the numbers listed below to find fault and repair.
Code
Item Diagnosis Chart
No.
12 Start code Normal -
14 EBCM function Abnormality in input/output, operational and B-3
control circuits
15 Power voltage drop B-4
21 G-sensor Wiring disconnection B-5
22 Brake light switch Wiring disconnection B-6
23 Transmission input Input abnormality B-7
32 Motor & motor relay
Shorted or disconnected coil B-8
41 FL wheel valve
Shorted or disconnected coil/wiring
42 FR wheel valve
Shorted or disconnected coil/wiring B-9
44 Rear wheel valve Shorted or disconnected coil/wiring
45 Valve relay Shorted or disconnected coil/wiring B-10
51 FL wheel speed sensor Disconnected coil/wiring
52 FR wheel speed sensor Disconnected coil/wiring B-11
53 RL wheel speed sensor Disconnected coil/wiring
54
RR wheel speed sensor Disconnected coil/wiring
61 FL wheel speed sensor Shorted coil/wiring
62 FR wheel speed sensor Shorted coil/wiring B-12
63 RL wheel speed sensor Shorted coil/wiring
64 RR wheel speed sensor Shorted coil/wiring
65 Sensor signal input Wrong number of teeth B-13

ENGINE DIAGNOSIS S-1
ENGINE
CONTENTS
Engine General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Section S
General
Engine Mechanical .................................................... Section SA
3.2L VS Engine ............................................................... Section SA1
Engine Cooling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Section S8
Engine Fuel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Section SC
Engine Electrical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Section SD
Driveability and Emissions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Section SE2
Engine Exhaust . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Section SF
SECTION 6
ENGINE GENERAL INFORMATION
CONTENTS
Description of Engine Section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S-1
General Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S-2
Engine Diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S-2
DESCRIPTION OF ENGINE SECTION
SECTIONS-ENGINE GENERAL INFORMATION SECTION S8-ENGINE COOLING
General description
Engine cleanliness and care, and general information
on engine service are covered in this section.
Engine diagnosis
This section covers the components of the fuel,
ignition, and mechanical systems that could cause a
particular complaint, and then outlines repairs in a
logical sequence.
SECTION SA-ENGINE MECHANICAL
This section contains information on the mechanical
parts of the engine, such as cylinder block, cylinder
head, crankshaft, pistons, valve train, camshaft, and
engine
lubrication.
Overhaul
procedures, removal and replacement
procedures, and specifications are also covered.
Specific subsections are:
SA-GENERAL;
Disassembly and reassembly procedures,
inspection and repair procedures
off the vehicle.
6A 1-3.2L V6 ENGINE;
Removal
and replacement procedures on the
vehicle.
Engine cooling system components such as radiator,
engine
coolant pump, thermostat, and cooling fan, are
covered
in this section.
SECTION SC-ENGINE FUEL
This section contains information on all the parts of the
fuel system except the fuel injectors, or throttle body II
unit itself. Items covered are: fuel tank, fuel pump, fuel
filter,
and fuel lines. Specific sections are used for each
fuel system type:
Port
Injection fuel rail and injectors will be found in
Section
6E2.
SECTION SD-ENGINE ELECTRICAL
Items covered in this section are battery, generator,
starter, ignition
coil, spark plugs and wires.
Ignition system diagnosis will be found in Section 6E2
as a "C4" chart.
Specific sections are:
601 -Battery
602 - Cranking System
603 -Charging System
604 -Ignition System

6-2 ENGINE DIAGNOSIS
SECTION 6E-DRIVEABILITY
AND EMISSIONS
This section covers emission control systems general
information, and diagnostic procedures which will lead
to repairing performance and driveability related
problems.
Emission components are covered, as well
as removal and replacement procedures.
Instructions on use
of special tools are also given.
SECTION 6F-ENGINE EXHAUST
This section has information on all exhaust system
parts, such
as tailpipes, mufflers, and the catalytic
converter.
GENERAL DESCRIPTION
ENGINE CLEANLINESS AND CARE
An automobile engine is a combination of many
machined, honed,
polished and lapped surfaces with
tolerances that are measured in the thousandths of a
millimeter (ten thousandths of an inch). Accordingly,
when any
internal engine parts are serviced, care and
cleanliness are important. Throughout this section, it
should be understood that proper cleaning and
protection
of machined surfaces and friction areas is
part
of the repair procedure. This is considered
standard shop practice even
if not specifically stated.
• A liberal coating of engine oil should be applied to
all friction areas during assembly to protect and
lubricate the surfaces on initial operation.
• Whenever valve train components, pistons, piston
rings, connecting rods, rod bearings, and
crankshaft
journal bearings are removed for
service, they should be retained in order.
• At the time of installation, they should be installed
in the same locations and with the same mating
surfaces
as when removed.
• Battery cables should be disconnected before any
major
work is performed on the engine. Failure to
disconnect
cables may result in damage to wire
harness
or other electrical parts.
• The six cylinders of this engine are identified by
numbers; Right side
cylinders 1, 3 and 5, Left side
cylinders 2, 4 and 6, as counted from crankshaft
pulley side to flywheel side.
GENERAL INFORMATION ON ENGINE
SERVICE
The following information on engine service should be
noted
carefully, as it is important in preventing damage
and contributing
to reliable engine performance.
• When raising or supporting the engine for any
reason,
do not use a jack under the oil pan. Due to
the
small clearance between the oil pan and the oil
pump strainer, jacking against the oil pan may
cause damage to the
oil pick-up unit.
• The 12-volt electrical system is capable of
damaging circuits. When performing any work
where electrical terminals could possibly be
grounded, the ground cable of the battery should
be disconnected at the battery.
• Any time the intake air duct or air cleaner is
removed, the intake opening
should be covered.
This
will protect against accidental entrance of
foreign material into the cylinder which could
cause extensive damage when the engine is
started.
ENGINE DIAGNOSIS
CONTENTS
Hard Starting . . . . . . . . . . . . . . . . . . . . . . . . . 6-3
Engine Compression
Test Procedure ..... 6-4
Rough Engine
Idling or Engine Stalling . . . 6-5
Rough Engine Running . . . . . . . . . . . . . . . . .
6-6
Hesitation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-7
Engine Lacks
Power . . . . . . . . . . . . . . . . . . . . 6-8
Engine
Noisy .......................... 6-10
Abnormal Combustion . . . . . . . . . . . . . . . . . . 6-12
Engine Oil Consumption Excessive . . . . . . . 6-13
Fuel Consumption Excessive ............. 6-14
Oil Problems . . . . . . . . . . . . . . . . . . . . . . . . . . 6-14
Malfunction Indicator Lamp . . . . . . . . . . . . . . 6-15
Engine Oil Pressure Check ............... 6-16
Inspection of Hydraulic Lash Adjuster . . . . . 6-17

ENGINE DIAGNOSIS 6-3
HARD STARTING
1. Starting motor does not turn over
Trouble shooting procedure
Turn on headlights and starter switch.
Condition Possible cause Correction
Headlights go out or dim Battery run down or under charged Recharge or replace battery
considerably
Terminals poorly connected Clean battery posts and
terminals and connect properly
Starting motor coil circuit shorted Overhaul or replace
Starting motor defective
Headlights stay
bright Starting motor circuit open Refer to Section 6D
Starting
motor coil open Replace
2. Ignition trouble -Starting motor turns over but engine does not start
Spark Test
Disconnect a high tension cable from any spark plug. Connect the spark plug tester J-26792 (ST-1 25).
start the engine, and check if a spark is generated in the spark plug tester.
Before starting the engine, make sure
that the spark plug tester is properly grounded. To avoid
electrical shock, do not touch the high tension cable while the engine is running.
Condition Possible cause Correction
Spark jumps across gap
Spark plug defective Clean, adjust spark gap or
replace
Ignition
timing incorrect Refer to Section 6E2
Fuel not reaching fuel injector(s) or Refer to item 3
engine (Trouble
in
fuel system)
Valve
timing incorrect Adjust
Engine
lacks compression Refer to item 4
(Engine
lacks compression)
No sparking takes
place Spark plug wire disconnected or broken Connect properly or replace
Electronic Ignition System with module Replace
Poor connections in engine harness
Correct
Engine Control
Module cable Correct or replace
disconnected or defective
3. Trouble in fuel system
Condition Possible cause Correction
Starting motor turns over and
Fuel tank empty Fill
spark occurs but engine does
not start. Water in fuel system Clean
Fuel filter clogged Replace filter
Fuel pipe clogged Clean or replace
Fuel pump defective
Replace
Fuel
pump circuit open Correct or replace
Evaporative Emission Control System Correct or replace
circuit clogged
Multipart Fuel Injection System faulty Refer to "Electronic Fuel
Injection"
section

6-4 ENGINE DIAGNOSIS
HARD STARTING (Cont'd)
4. Engine lacks compression
Condition Possible cause
Spark plug loosely fitted or spark plug
gasket defective
Valve timing incorrect
Cylinder head gasket defective
Valve incorrectly seated
Valve stem seized
Valve spring weakened
Cylinder or piston rings worn
Piston ring seized
ENGINE COMPRESSION TEST
PROCEDURE
1. Start and run the engine until the engine reaches
normal operating temperature.
2. Turn the engine off.
3. Remove all the spark plugs.
4. Remove ignition coil fuse (15A) and disable the
ignition system.
5. Remove the fuel pump relay from the relay and
fuse box.
6. Engage the starter and check that the cranking
speed is approximately
300 rpm.
7. Install cylinder compression gauge into spark plug
hole.
8. With the throttle valve opened fully, keep the
starter engaged
until the compression gage
needle reaches the
maximum level. Note the
reading.
9. Repeat the test with each cylinder.
If
the compression pressure obtained falls below the
limit, engine overhaul is necessary.
Limit; 883
kPa (128 psi) Correction
Tighten
to specified torque or
replace gasket
Adjust
Replace gasket
Lap
valve
Replace valve
and valve guide
Replace
Overhaul engine
Overhaul engine.

6-6 ENGINE DIAGNOSIS
ROUGH ENGINE RUNNING
Complaint
Faulty parts Possible cause Correction
Engine misfires Ignition coil
Coil layer shorted Replace
regularly
high-tension Primary lead wire broken leakage due
Correct cables to defective insulator
Spark plugs
Fouling Clean
or install hotter type
plug
Insulator
nose leaking Replace
Fuel
injectors Fuel injector(s) defective Replace
Dropping register defective Replace
Engine Control
Faulty Replace
Module
Engine knocks Spark plugs
Spark plugs running too hot Install colder type spark
regularly
plugs
Engine Control Faulty
Replace
Module
Engine lacks Spark plugs
Fouled Clean
power Multipart Fuel
Fuel injectors defective Replace
Injection Manifold Absolute Pressure (MAP)
Correct or replace system Sensor or Manifold Absolute Pressure
Sensor
circuit defective
Engine
Coolant Temperature Sensor or Correct or replace
Engine Coolant Temperature Sensor
circuit dcefective
Engine
Control Module faulty Replace
Intake
Air Temperature Sensor or Intake
Air Temperature Sensor circuit Correct or replace
defective
Throttle Position Sensor or Throttle Correct or replace
Position Sensor
circuit defective
Knock
Sensor or Knock Sensor circuits Correct or replace
defective (DOHC only)
Knock Sensor Module or Knock Sensor Correct or replace .
Module
circuits defective (DOHC only)
•

ENGINE DIAGNOSIS 6-9
ENGINE LACKS POWER (Cont'd)
Condition Possible cause Correction
Engine overheating
Level of Engine Coolant too low Replenish
Thermo switch or fan motor defective Replace
Thermostat defective Replace
Engine
Coolant pump defective Correct or replace
Radiator clogged
Clean or replace
Radiator
filler cap defective Replace
Level
of oil in engine crankcase too low Change or replenish
or
wrong oil engine
Resistance in exhaust system
Clean exhaust system or
increased replace
defective parts
Throttle Position Sensor adjustment Adjust
Wide Open Throttle
incorrect switch setting
Throttle Position Sensor circuit open
or Correct or replace
shorted
Cylinder head gasket damaged Replace
Engine overcooling
Radiator
overcooling Install cover
in front of
radiator
Thermostat defective Replace
(Use a thermostat set
to open at a2·c (180.F))
Engine
lacks compression Refer to Hard Start
Others Tire inflation pressure
abnormal Adjust to recommend
pressures
Brake drag Adjust
Clutch slipping Adjust or replace
Level
of oil in engine crankcase too Correct level of engine oil
high
Exhaust Gas
Recirculation Valve Replace
defective
Back pressure transducer defective
Replace