check engine ISUZU TF SERIES 2004 Owner's Manual

5A-84 BRAKE CONTROL SYSTEM

DTC C0277 (Flash Code 77) Power Supply Low Input
DTC C0278 (Flash Code 78) Power Supply High Input



RTW45AMF000201

Step Action
Value(s) Yes No
1 Was the “Basic Diagnostic Flow Chart” performed?
- Go to Step 2 Go to Basic
Diagnostic
Flow Chart
2 1. Check for a poor connection at EHCU
2. If a problem is found, repair as necessary.
Was a problem found?
- Verify repair Go to Step 3
3 1. Ignition “OFF”, disconnect EHCU.
2. Ignition “ON”, engine “OFF”.
3. Check the supply voltage to EHCU.
Was the value normal? Battery
Voltage Go to Step 5 Go to Step 4
4 Repair or replace the power supply circuit.
Was the action complete? - Verify repair -
5 1. Check the power supply circuit.
(Circuit for an open, short to ground, or short to
voltage.)
2. If a problem is found, repair as necessary.
Was a problem found?
- Verify repair Go to Step 6

BRAKE CONTROL SYSTEM 5A-85

Step Action
Value(s) Yes No
6 1. Ignition “ON,” engine “OFF.”
2. Select “Display DTCs” with the Tech 2.
Note: Perform the various tests (actuator test, test
run, brake test, etc.) then observe the DTC with a
Tech2.
Are any DTCs stored? - Go to Step 7 Verify repair
7 Replace EHCU.
Note : Check the EHCU type for specification, when
the EHCU is replaced.
(Specification ; 2WD model or 4WD model)
Was the action complete? - Verify repair -

BRAKE CONTROL SYSTEM 5A-87

Step Action
Value(s) Yes No
5 1. Ignition "OFF".
2. Connect 2-4WD control unit.
3. Disconnect EHCU.
4. Ignition "ON," engine "OFF."
5. Install the high impedance digital multimeter.
6. Check the transfer (2-4WD control unit) signal
value.
Was the value normal? Transfer 2WD
Mode: 8.3Hz
(
15%)
Transfer 4WD
Mode: 4.2Hz
(
15%) Go to Step 7 Go to Step 6
6 Replace 2-4WD control unit.
Was the action complete?
- Go to Step 7 -
7 1. Ignition “ON,” engine “OFF.”
2. Select “Display DTCs” with the Tech 2.
Note: Perform the various tests (actuator test, test
run, brake test, etc.) then observe the DTC with a
Tech2.
Are any DTCs stored? - Go to Step 8 Verify repair
8 Replace EHCU.
Note : Check the EHCU type for specification, when
the EHCU is replaced.
(Specification ; 2WD model or 4WD model)
Was the action complete? - Verify repair -

BRAKE CONTROL SYSTEM 5A-89

Step Action Value(s) Yes No
4 1. Ignition "OFF".
2. Check for a poor condition at the EHCU harness
connector.
3. Check the EHCU circuit for an open, short to
ground, or short to voltage. Also, check the EHCU
ignition feed circuit for an open or short to ground
and the EHCU ground circuit for an open or short
to voltage.
4. If a problem is found, repair as necessary.
Was a problem found? - Verify repair Go to Step 9
5 1. Ignition "OFF," disconnect the EHCU and G-
sensor.
2. Check the circuit between EHCU and G-sensor.
(short to ground, or short to voltage.)
3. If a problem is found, repair as necessary.
Was a problem found? - Verify repair
Go to Step 6 Go to Step 6
6 1. Remove the G-sensor.
2. Reconnect G-sensor and EHCU
3. Install the Tech 2.
4. Ignition "ON", engine "OFF".
5. Observe the G-sensor reading on Tech 2.
If G-sensor inclines, reading voltage will change.
Is the reading voltage between specified value? 1.0 – 4.0 V Go to Step 7 Go to Step 8
7 1. Ignition "OFF".
2. Install the G-sensor.
3. Install the Tech 2.
4. Ignition "ON", engine "OFF".
5. Select "Display DTCs" with the Tech 2.
Are any DTCs stored? - Go to Step 8 Verify repair
8 1. Replace G-sensor.
2. Select "Display DTCs" with the Tech 2.
Note: Perform the various tests (actuator test, test
run, brake test, etc.) then observe the DTC with a
Tech2.
Are any DTCs stored? - Go to Step 9 Verify repair
9 Replace EHCU.
Note : Check the EHCU type for specification, when
the EHCU is replaced.
(Specification ; 2WD model or 4WD model)
Was the action complete? - Verify repair -

BRAKES 5C-25


Filling Master Cylinder Reservoir
CAUTION :
Use only specified brake fluid. Do not use any fluid which
contains a petroleum base. Do not use a container which
has been used for petroleum based fluids or a container
which is wet with water. Petroleum based fluid will cause
swelling and distortion of rubber parts in the hydraulic
brake system. Water mixed with brake fluid lowers the
fluid boiling point. Keep all fluid containers capped to
prevent contamination.
Always fill the master cylinder reservoir when the engine
is cold.
Never allow the brake fluid to come in contact with the
painted surfaces.
The master cylinder reservoir must be kept properly filled
to ensure adequate reserve and to prevent air and
moisture from entering the hydraulic system. However,
because of expansion due to heat absorbed from the
brakes and the engine, the reservoir must not be
overfilled. Thoroughly clean reservoir cap before removal
to avoid getting dirt into reservoir. Add fluid as required to
bring level to the “MAX” mark on the reservoir tank. Use
“DOT 3” Hydraulic Brake Fluid.

Leakage of Brake Fluid
With engine idling, set shift lever in the neutral position and
continue to depress brake pedal at a constant pedal
application force.
Should the pedal stroke become deeper gradually, leakage
from the hydraulic pressure system is possible.
Make sure by visual check that there is no leak.




BLEEDING OF THE BRAKE HYDRAULIC
CIRCUIT
If air enters the bake lines, it will cause poor brake action.
Therefore, bleeding should be performed if the brakes have
been used with the level of brake fluid in the reservoir
excessively low or if brake pipes have been disconnected in
the course of brake servicing.
Bleeding operation calls for co-operative action of 2 persons.

Set the parking brake firmly while bleeding.

Perform bleeding operation with ENGINE RUNNING, to
prevent damage to push rod seal.

Make sure exhaust is suitably ventilated.

Bleed the hydraulic system with the fluid reservoir filled to
the specified level.

Bleed the system starting with the rear wheel cylinde
r
farthest from the master cylinder.

5C-26 BRAKES


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 disconnected at one wheel, only that
wheel cylinder/caliper needs to be bled. If the pipes are
disconnected at any fitting located between the master cylinder
and brakes, then the brake system served by the disconnected
pipe must be bled.

1. 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.
2. Remove the master cylinder reservoir cap.

3. Fill the master cylinder reservoir with brake fluid. Keep the
reservoir at least half full during the air bleeding operation
4. Always use new brake fluid for replenishment.
5. In replenishing rake fluid, take care that air bubbles do no
t
enter the brake fluid.


When the master cylinder is replaced or overhauled, firs
t
bleed the air from the master cylinder, then from each
wheel cylinder and caliper following the procedures
described below.


Bleeding the Master Cylinder
6. Disconnect the rear wheel brake pipe (1) from the master
cylinder.
Check the fluid level and replenish as necessary. If
replenished, leave the system for at least one minute.
7. Depress the brake pedal slowly once and hold it depressed.
8. Completely seal the delivery port of the master cylinder with
your finger, where the pipe was disconnected then release
the brake pedal slowly.
9. Release your finger from the delivery port when the brake
pedal returns completely.
10. Repeat steps 7 through 9 until the brake fluid comes out o
f
the delivery port during step 7.
NOTE : Do not allow the fluid level in the reservoir to go below
the half-way mark.
11. Reconnect the brake pipe (1) to the master cylinder and
tighten the pipe.
12. Depress the brake pedal slowly once and hold it depressed.
13. Loosen the rear wheel brake pipe (1) at the master cylinder.
14. Retighten the brake pipe, then release the brake pedal
slowly.

5C-28 BRAKES


27. After the bleeding operation is completed on the each
individual wheel, check the level of the brake fluid in the
reservoir and replenish up to the “MAX" level as necessary.
28. Attach the reservoir cap.
29. Stop the engine.




05007-1


BRAKE LINE (HOSES AND PIPES)

Inspect all hoses and pipes for wear, bending, chafing,
cracks, dents, or any other damage.
Make necessary correction or parts replacement if these
abnormal conditions are found through inspection.

All hoses, pipes and joints can be damaged easily.
Do not allow the hose to become excessively twisted and
bent when working with then, and pay special attention to all
the brake lines not to damage them when repairing o
r
replacing other parts (axle, suspension, etc).

Inspection for leakage should be performed by depressing
the brake pedal fully.
If leakage is apparent at the circumference of joints,
retighten or replace these parts.
This procedure must be performed whenever brake lines
are installed.

After disconnecting the hoses and pipes, cap or tape the
openings to prevent entry of foreign material.

5C-60 BRAKES
Inspection and Repair
Vacuum Hose (The built in check valve)
360R300002


1) Inspect the check valve (2), which is installed inside the
vacuum hose.
2) Blow air into the hose from the booster side as shown in
the illustration. The air should pass freely through the
hose.
3) Blow air into the hose from the engine side. The check
valve should close to block the passage of air.
The vacuum hose and built-in check valve must be
replaced as a set if either is found to be defective.

Important Operation-Installation
8. Vacuum Booster Assembly
7. Vacuum Booster Fixing Nut
6. Snap Pin
1) Perform vacuum booster and vacuum booster push rod
adjustment.
Note :
When replacing either the master cylinder or vacuum booster,
be sure to measure push rod, and adjust if required.

RTW35CSH000901

2) Measure the dimension (B) of master cylinder.


3) Apply negative pressure by means of vacuum pump so
that the pressure in the vacuum booster becomes
GASOLINE ENGINE: 66.7 kPa (500 mm Hg) or DIESEL
ENGINE 93.3 kPa (700 mm Hg).
Note :
Be sure to apply NEGATIVE pressure after installing a push
rod gauge on the vacuum booster.

5C-62 BRAKES
360r300003
5. Vacuum Hose
The check valve (2) is built-in to the vacuum hose.
When installing the vacuum hose make sure that the arrow on
the hose is facing the engine (1).
Note :

Do not apply oil to the vacuum hose.



Installation direction is very important. The booster will no
t
operate if the vacuum hose is installed in the wrong
direction.


4JA1-T/4JA1-TC/4JH1-TC LHD model (with 2nd Battery)


RTW45CLF000101

ELECTRICAL-BODY AND CHASSIS 8A-19
Battery-1

BATTERY
Inspection
1. Check the battery terminals 1 for corrosion.
2. Check the battery cables
2 for looseness.
3. Check the battery case
3 for cracks and other damage.
4. Check the battery electrolyte level.

Battery-2

Battery Replacement
1. Disconnect the battery ground cable 1.
2. Disconnect the battery positive cable
2.
3. Remove the battery clamp
3.
4. Remove the battery
Caution:
It is important that the battery ground cable be removed
first.
Removing the battery positive cable first can result in a
short circuit.


Jump Starting the Engine with a Booster Battery
The following description assumes that you are using a booster
battery mounted on a second vehicle.
The listed steps (with some minor modifications) are also
applicable if you are using a naked booster battery or special
battery charging equipment.