Isuzu Trooper (1998-2002 year). Manual - part 213

5C – 4 POWER ASSISTED BRAKE SYSTEM

rod length. If an incorrect length push rod is found,
adjust or replace the push rod. Check the brake pedal
travel and the parking brake adjustment.
When checking the fluid level, the master cylinder
fluid level may be low from the “MAX” mark if the
front and rear linings are worn. This is not abnormal.

WARNING LIGHT OPERATION

When the ignition switch is in the START position, the
“BRAKE” warning light should glow and go OFF when
the ignition switch returns to the ON position.
The following conditions will activate the “BRAKE”
light:
1. Parking brake applied. The light should be ON

whenever the parking brake is applied and the
ignition switch is ON.

2. Low fluid level. A low fluid level in the master

cylinder will turn the “BRAKE” light ON.

3. During engine cranking the “BRAKE” light should

remain ON. This notifies the driver that the
warning circuit is operating properly.

4. Low vacuum warning light. The vacuum warning

device is equipped on the diesel engine equipped
vehicles. The “BRAKE” light comes on when the
reserved vacuum is lowered to a critical level or
power brake line is damaged.

NOTE:

Depressing the brake pedal repeatedly may cause the
brake warning light to come ON when the engine is
running at idling speed or at low speed. This is
because the amount of vacuum is used more than
that supplied by the vacuum pump, however, no
problem will occur actually.

If the lamp is still lighting even after 2 or 3 seconds at
idling speed, the vacuum line may be defective.

ANTILOCK BRAKE SYSTEM (ABS)

Refer to Brake Control System for inspection and
diagnosis procedure of the hydraulic unit.

POWER ASSISTED BRAKE SYSTEM  5C – 5

TROUBLESHOOTING

Condition

Possible Cause

Correction

Brake Pull

1. Tire inflation pressures unequal.

1. Adjust

2. Front wheel alignment incorrect.

2. Adjust

3. Unmatched tires on same axle.

3. Tire with approx. the same amount of

tread should be used on the same axle.

4. Restricted brake pipes or hoses. 

4. Check for soft hoses and damaged 

lines. Replace with new hoses and new 
double-walled steel brake piping.

5. Water or oil on brake pads.

5. Clean or replace.

6. Brake pads hardened.

6. Replace.

7. Brake pads worn excessively.

7. Replace.

8. Brake rotor worn or scored.

8. Grind or replace.

9. Disc brake caliper malfunctioning.

9. Clean or replace.

10. Front hub bearing preload incorrect.

10. Adjust or replace.

11. Loose suspension parts.

11. Check all suspension mountings.

12. Loose calipers.

12. Check and tighten bolts to specifications.

Brake 

1. Excessive lateral runout.

1. Check per instructions.

Roughness-or

If not within specifications, replace or

Chatter

machine the rotor.

(Pulsates)

2. Parallelism not within specifications.

2. Check per instructions.

If not within specifications, replace or 
machine the rotor.

3. Wheel bearings not adjusted.

3. Adjust wheel bearings to correct

specifications.

4. Pad reversed (steel against iron).

4. Replace brake pad and machine rotor

to within specifications.

Excessive 

1. Malfunctioning vacuum booster.

1. Check vacuum booster operation and

Pedal 

repair, if necessary.

Effort

2. Partial system failure.

2. Check front and rear brake system for

failure and repair. Also, check brake
warning light. If a failed system is
found, the light should indicate a 
failure.

3. Excessively worn pad.

3. Check and replace pads in sets.

4. Piston in caliper stuck or sluggish.

4. Remove caliper and rebuild.

5. Fading brakes due to incorrect pad.

5. Remove and replace with original

equipment pad or equivalent.

6. Vacuum leak to vacuum booster.

6. Check for ruptured or loose hose.

7. Check direction of check valve within

7. Correct vacuum hose direction.

vacuum hose.

8. Grease on the brake pads.

8. Replace or clean.

Excessive 

1. Air in hydraulic circuit.

1. Bleed hydraulic circuit.

Brake Pedal 

2. Level of brake fluid in resevoir too low.

2. Replenish brake fluid resevoir to

Travel

specified level and bleed hydraulic
circuit as necessary.

3. Master cylinder push rod clearance

3. Adjust.

excessive.

4. Leakage in hydraulic system.

4. Correct or replace defective parts.

5C – 6 POWER ASSISTED BRAKE SYSTEM

Condition

Possible Cause

Correction

Brake Drag

1. Master cylinder pistons not returning

1. Adjust stop light switch and vacuum

correctly.

booster operating rod. If necessary,
rebuild.

2. Restricted brake pipes or hoses.

2. Check for soft hoses or damaged pipes,

and replace with new hoses and new
double-walled steel brake piping.

3. Parking brake maladjusted.

3. Adjust.

4. Parking brake lining clearance

4. Adjust.

insufficient.

5. Brake pedal free play insufficient.

5. Adjust brake pedal height or power

cylinder operating rod.

6. Piston in master cylinder sticking.

6. Replace.

7. Piston in disc brake caliper sticking.

7. Replace piston seals.

8. Brake pads sticking in caliper.

8. Clean.

9. Return spring weakened.

9. Replace.

10. Parking brake binding.

10. Overhaul parking brakes and correct.

11. Front hub bearing preload incorrect.

11. Adjust or replace.

12. Parking brake shoes not returning.

12. Correct or replace brake back plate and

brake shoe as necessary.

13. Obstructions in hydraulic circuit.

13. Clean.

14. Rotor warped excessively.

14. Grind or replace.

15. Rear brake drum distorted.

15. Grind or replace.

16. Parking cable sticking.

16. Clean or replace.

Grabbing or

1. Malfunctioning vacuum booster.

1. Check operation and correct as

Uneven 

necessary.

Braking Action 

2. Binding brake pedal mechanism.

2. Check and lubricate, if necessary.

(All conditions

3. Corroded caliper assembly.

3. Clean and lubricate.

listed under
“Pulls”)

Brake Noisy

1. Brake pads worn.

1. Replace.

2. Brake pads hardened.

2. Replace.

3. Brake pads in poor contact with rotor.

3. Correct.

4. Brake disc(s) warped, worn or

4. Grind or replace.

damaged.

5. Disc brake anti-squeak shims fatigued.

5. Replace.

6. Front hub bearings loose or preload is

6. Adjust or replace.

incorrect.

7. Brake disc rusted.

7. Grind or replace.

Poor Brake

1. Master cylinder faulty.

1. Correct or replace.

Action

2. Vacuum booster faulty.

2. Correct or replace.

3. Level of brake fluid in reservoir too

3. Replenish and bleed.

low.

4. Air in hydraulic circuit.

4. Bleed.

5. Disc brake caliper faulty.

5. Clean or replace.

6. Water or oil on brake pads.

6. Clean or replace.

7. Brake pads in poor contact with rotor.

7. Correct.

8. Brake pads worn.

8. Replace.

9. Brake disc rusted.

9. Grind or replace.

10. Check valve in vacuum hose faulty.

10. Correct or replace.

POWER ASSISTED BRAKE SYSTEM  5C – 7

MAIN DATA AND SPECIFICATIONS

MASTER CYLINDER

Type

Dual-circuit

Piston Bore Diameter

mm (in)

25.4 (1.000)

VACUUM BOOSTER

Diaphragm Diameter

Front; mm (in)

205 (8.07) (Gasoline) / 180 (7.09) (Diesel)

Rear; mm (in)

230 (9.06) (Gasoline) / 205 (8.07) (Diesel)

Push Rod Stroke

mm (in)

More than 32.0 (1.26)

Plunger Diameter

mm (in)

10.13 (0.399)

Push Rod Diameter

mm (in)

27.4 (1.08)

FRONT DISC BRAKE

Type

Floating, Pin Slide

Pad Dimension

cm

2

(in

2

)

55 (8.52)

Adjusting Method

Self-adjusting

Piston Diameter

mm (in)

60.33 (2.38)

Disc (Rotor) Type

Ventilated

Disc (Rotor) Thickness

mm (in)

26 (1.02)

Disc (Rotor) Effective Diameter

mm (in)

222 (8.74)

REAR DISC BRAKE

Type

Floating, Pin Slide

Pad Dimension

cm

2

(in

2

)

33 (5.11)

Adjusting Method

Self-adjusting

Piston Diameter

mm (in)

41.3 (1.63)

Disc (Rotor) Type

Ventilated

Disc (Rotor) Thickness

mm (in)

18 (0.71)

Disc (Rotor) Effective Diameter

mm (in)

269.2 (10.60)