1998 ISUZU TROOPER relay

5A±20
BRAKE CONTROL SYSTEM
Part Location (LHD model)
D08RW808
Legend
(1) F±2
(2) F±3
(3) H±33
(4) H±7, H±8, H±25
(5) H±46
(6) C±16
(7) C±63
(8) Fuse Box
(9) B±13 or B±14
(10) C±13
(11) H±5
(12) H±10, H±11(13) E±30
(14) C±41
(15) H±42
(16) C±85
(17) C±4 (EHCU)
(18) Relay & Fuse Box
(19) C±39
(20) H±12, H±13, H±15, H±16
(21) E±47, E±48, M±1
(22) E±42, E±43, M±8
(23) B±25
(24) I±10
(25) I±9

5A±34
BRAKE CONTROL SYSTEM
Part Location (RHD model)
D08RW623
Legend
(1) F±2
(2) F±3
(3) H±33
(4) H±7
(5) H±46
(6) C±16
(7) E±42, E±43, M±8
(8) E±47, E±48, M±1
(9) B±13 or B±14
(10) C±13
(11) H±4, H±5, H±6
(12) H±10, H±11
(13) E±4 (4JX1)(14) E±30 (4GJ2, 6VD1/6VE1)
(15) Fuse Box
(16) H±42
(17) C±41
(18) C±85
(19) C±4 (EHCU)
(20) Relay & Fuse Box
(21) C±39
(22) H±13, H±15, H±16, H±26, H±27
(23) I±10
(24) I±9
(25) H±12
(26) C±63
(27) B±25

5A±39 BRAKE CONTROL SYSTEM
Diagnostic Trouble Codes
Choose and trace an appropriate flowchart by the
numbers listed below to find fault and repair.
Code
ItemDiagnosisChart No.
12Start CodeNormalÐ
14EHCU FunctionAbnormality in input/output, operational and
control circuitsB-2
15Power Voltage DropB-3
16CLASS±2 Communication Line Ab-
normalityB-4
21G-sensorWiring disconnectionB-5
23Transmission InputInput abnormalityB-6
24Transfer MonitorB-7
32Motor & Motor RelayShorted or disconnected coilB-8
35Valve RelayShorted or disconnected coil/wiringB-9
41FL Holding Solenoid ValveShorted or disconnected coil/wiringB-10
42FL Decompression Solenoid ValveShorted or disconnected coil/wiringB-11
43FR Holding Solenoid ValveShorted or disconnected coil/wiringB-12
44FR Decompression Solenoid ValveShorted or disconnected coil/wiringB-13
45Rear Holding Solenoid ValveShorted or disconnected coil/wiringB-14
46Rear Decompression Solenoid ValveShorted or disconnected coil/wiringB-15
51FL Wheel Speed SensorDisconnected coil/wiringB-16
52FR Wheel Speed SensorDisconnected coil/wiringB-17
53RL Wheel Speed SensorDisconnected coil/wiringB-18
54RR Wheel Speed SensorDisconnected coil/wiringB-19
61FL Wheel Speed SensorShorted coil/wiringB-20
62FR Wheel Speed SensorShorted coil/wiringB-21
63RL Wheel Speed SensorShorted coil/wiringB-22
64RR Wheel Speed SensorShorted coil/wiringB-23
65Sensor Signal InputWrong number of teethB-24

5A±47 BRAKE CONTROL SYSTEM
Chart B-7 Transfer Monitor (DTC 24)
StepActionYe sNo
11. Turn the key off.
2. Disconnect EHCU connector.
Is the EHCU connector terminal 9 line normally?
Go to Step 2
Repair
Go to Step 3
2Is the TOD ECU or 4WD controller normal?
Replace EHCU.
Go to Step 3
Repair or replace
TOD ECU or
4WD contrder.
Go to Step 3
31. Reconnect all components, ensure all components are
properly mounted.
2. Clear diagnostic trouble code.
Was this step finished?
Repeat the ªBasic
diagnostic flow
chart.º
Go to Step 3
Chart B-8 EHCU Pump Motor And Motor Relay Circuit (DTC 32)
StepActionYe sNo
11. Turn the key off.
2. Disconnect EHCU connector.
3. Measure voltage between EHCU connector terminal 13 and
body ground.
Is the voltage equal to battery voltage?
Go to Step 2
Repair
fuse/harness
between battery
and EHCU
connector
terminal 13.
Go to Step 3
2Is there continuity between EHCU connector terminal 12 and
ground?
Go to Step 3
Repair between
EHCU connector
terminal 12 and
ground.
Go to Step 3
31. Reconnect all components and ensure all components are
properly mounted.
2. Clear diagnostic trouble code.
Was this step finished?
Repeat the ªBasic
diagnostic flow
chart.º
Go to Step 3
Chart B-9 EHCU Pump Valve And Valve Relay Circuit (DTC 35)
StepActionYe sNo
11. Turn the key off.
2. Disconnect EHCU connector.
3. Measure voltage between EHCU connector terminal 14 and
body ground.
Is the voltage equal to battery voltage?
Replace EHCU.
Go to Step 2
Repair fuse and
harness EHCU
connector
terminal 14 and
battery.
Go to Step 2
21. Reconnect all components and ensure all components are
properly mounted.
2. Clear diagnostic trouble code.
Was this step finished?
Repeat the ªBasic
diagnostic flow
chart.º
Go to Step 2

5C – 10 POWER ASSISTED BRAKE SYSTEM
BLEEDING BRAKE HYDRAULIC SYSTEM
A bleeding operation is necessary to remove air from
the hydraulic brake system whenever air is introduced
into the hydraulic system. It may be necessary to
bleed the hydraulic system at all four brakes if air has
been introduced through a low fluid level or by
disconnecting brake pipes at the master cylinder. If a
brake pipe is disconneted at one wheel, only that
wheel cylinder/caliper needs to be bled. If pipes are
disconnected at any fitting located between master
cylinder and brakes, then the brake system served by
the disconnected pipe must be bled.
1. For 4-wheel Antilock Brake System (ABS)
equipped vehicle, be sure to remove the ABS main
fuse 40A located at the relay and fuse box before
bleeding air. If you attempt to bleed air without
removing the main fuse, air cannot be let out
thoroughly, and this may cause damage to the
hydraulic unit. After bleeding air, be sure to
replace the ABS main fuse back to its original
position.
2. Set the parking brake completely, then start the
engine.
NOTE:
The vacuum booster will be damaged if the bleeding
operation is performed with the engine off.
3. Remove the master cylinder reservoir cap.
4. Fill the master cylinder reservoir with brake fluid.
Keep the reservoir at least half full during the air
bleeding operation.
5. Always use new brake fluid for replenishment.
6. In replenishing brake fluid, take care that air
bubbles do not enter the brake fluid.
•When the master cylinder is replaced or
overhauled, first bleed the air from the master
cylinder, then from each wheel cylinder and
caliper following the procedures described
below.
Bleeding the Master Cylinder
7. Disconnect the rear wheel brake pipe 1from the
master cylinder. Check the fluid level and
replenish as necessary. If replenished, leave the
system for at least one minute.
8. Depress the brake pedal slowly once and hold it
depressed.
9. Completely seal the delivery port of the master
cylinder where the pipe was disconnected with
your finger, then release the brake pedal slowly.
10. Release your finger from the delivery port when
the brake pedal returns completely.
11. Repeat steps 7 through 9 until the brake fluid
comes out of the delivery port during step 7.
NOTE:
Do not allow the fluid level in the reservoir to go
below the half-way mark.
21

6A±5
ENGINE MECHANICAL
4. Engine Lacks Compression
Condition
Possible causeCorrection
Engine lacks compressionSpark plug loosely fitted or spark
plug gasket defectiveTighten to specified torque or replace
gasket
Valve timing incorrectAdjust
Cylinder head gasket defectiveReplace gasket
Valve incorrectly seatedLap valve
Valve stem seizedReplace valve and valve guide
Valve spring weakened or brokenReplace
Cylinder or piston rings wornOverhaul engine
Piston ring seizedOverhaul engine.
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; 1000 kPa (145 psi)

6A±6
ENGINE MECHANICAL
Rough Engine Idling or Engine Stalling
ConditionPossible causeCorrection
Trouble in fuel injection systemIdle air control valve defectiveReplace
Throttle shutting off incompleteCorrect or replace
Throttle position sensor circuit open
or shortedCorrect or replace
Fuel injector circuits open or shortedCorrect or replace
Fuel injectors damagedReplace
Fuel pump relay defectiveReplace
Mass Airflow Sensor circuit open or
poor connectionsCorrect or replace
Mass Airflow Sensor defectiveReplace
Manifold Absolute Pressure Sensor
circuit open or poor connectionsCorrect or replace
Manifold Absolute Pressure Sensor
defectiveReplace
Engine Coolant Temperature Sensor
circuit open or poor connectionsCorrect or replace
Engine Coolant Temperature Sensor
defectiveReplace
Intake Air Temperature sensor circuit
open or poor connectionsCorrect or replace
Intake Air Temperature sensor
defectiveReplace
Knock Sensor (KS) cable broken or
poor connectionsCorrect or replace
KS defectiveReplace
KS Module circuits open or groundCorrect or replace
KS Module defectiveReplace
Vehicle Speed Sensor circuit open or
shortedCorrect or replace
Vehicle Speed Sensor defectiveReplace
Trouble in emission control systemPowertrain Control Module defectiveReplace
Exhaust Gas Recirculation Valve
circuit open or poor connectionsCorrect or replace
Exhaust Gas Recirculation Valve
faultyReplace
Canister purge valve circuit open or
poor connectionsCorrect or replace
Canister purge valve defectiveReplace
Evaporative Emission Canister
Purge control valve defectiveReplace
Trouble in ignition systemRefer to ªHard Startº

6A±13
ENGINE MECHANICAL
Condition CorrectionPossible cause
Engine knockingPreignition due to use of spark plugs
of inadequate heat rangeInstall Spark Plugs of adequate heat
range
Carbon deposits in combustion
chambersClean
Fuel too low in octane ratingReplace fuel
Wide Open Throttle enrichment
system failureRefer to Section 6E
Selection of transmission gear
incorrectCaution operator of incorrect gear
selection
Engine overheatingRefer to ªEngine Lacks Powerº
OthersWater pump defectiveReplace
Drive belt slippingReplace auto tentioner or drive belt
Abnormal Combustion
ConditionPossible causeCorrection
Trouble in fuel systemFuel pressure control valve defectiveReplace
Fuel filter cloggedReplace
Fuel pump cloggedClean or replace
Fuel tank or fuel pipe cloggedClean or replace
Fuel injector cloggedClean or replace
Fuel pump relay defectiveReplace
Power supply cable for fuel pump
broken or poor connectionsReconnect, correct or replace
Mass Airflow (MAF) sensor circuit
open or defectiveCorrect or replace
MAF Sensor defectiveReplace
Manifold Absolute Pressure Sensor
circuit open or shortedCorrect or replace
Manifold Absolute Pressure Sensor
defectiveReplace
Engine Coolant Temperature (ECT)
Sensor circuit open or shortedCorrect or replace
ECT Sensor defectiveReplace
Throttle Position Sensor adjustment
incorrectReadjust
Throttle Position Sensor defectiveReplace
Throttle Position Sensor connector
poor connectionsReconnect
Vehicle Speed Sensor cable poor
connections or defectiveCorrect or replace
Vehicle Speed Sensor loosely fixedFix tightly
Vehicle Speed Sensor in wrong
contact or defectiveReplace
Powertrain Control Module cable
poor connections or defectiveCorrect or replace