GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Isuzu 🢒 1999 🢒 S/T Isuzu - 4WD 🢒 Brakes 🢒 Hydraulic Brakes 🢒 Brake System Slow Release

Step

Action

Value(s)

Yes

No

1

Did you perform the Hydraulic Brake System Diagnostic Check?

--

Go to Step 2

Go to Hydraulic Brake Diagnostic System Check

2

Inspect the park brake lever for proper operation by performing the following steps:

  1. Turn the ignition switch to the ON position.
  2. Press the park brake pedal until it stops. Verify that the Brake Warning Lamp is ON.
  3. Pull the park brake release lever. Verify that the Brake Warning Lamp is OFF.

Did the park brake warning lamp turn OFF and the pedal return to the original height?

--

Go to Step 4

Go to Step 3

3
  1. Inspect the park brake pedal assembly for interference, binding or for broken components.
  2. Lubricate the park brake pedal assembly.
  3. If lubricating the park brake pedal assembly does not solve the problem, replace the park brake pedal. Refer to Park Brake Lever Assembly Replacement in Park Brake.

Is the repair complete?

--

Go to Step 33

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4
  1. Start the engine.
  2. Shift the vehicle into DRIVE.
  3. Attempt to move the vehicle by slowly pressing the accelerator pedal.

Does the engine RPM increase without the vehicle moving?

--

Go to Step 5

Go to Step 7

5

Inspect the park brake cables for corrosion, kinks, or interference with other components.

Are the park brake cables corroded, kinked, or interfering with other components?

--

Go to Step 6

Go to Step 7

6

Realign or replace the park brake cable(s). Refer to the appropriate procedure:

    •  Parking Brake Front Cable Replacement in Park Brake
    •  Parking Brake Rear Cable Replacement in Park Brake

Is the repair complete?

--

Go to Step 33

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7
  1. Remove the brake drum.
  2. Inspect the brake linings for the following conditions:
    3. • Excessive wear
    • Uneven wear
    • Abuse
    • Glazing
    • Contaminated lining material
    • Incorrect lining material

Refer to Brake Shoe Inspection in Drum Brakes.

Do any of the above conditions apply?

--

Go to Step 8

Go to Step 9

8

Replace the brake shoe linings. Refer to Brake Shoe Replacement in Drum Brakes.

Is the repair complete?

--

Go to Step 9

Go to Step 10

9

Inspect the brake shoe mounting hardware and springs for corrosion or binding.

Is the mounting hardware or springs corroded or binding?

-

Go to Step 10

Go to Step 11

10

Replace the mounting hardware or springs as necessary.

Is the repair complete?

--

Go to Step 33

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11

Inspect the park brake lever for corrosion and free movement without binding.

Does the park brake lever move freely without binding?

--

Go to Step 12

Go to Step 13

12

Clean the park brake lever components. Inspect for proper movement. If the park brake lever still does not move freely, replace the park brake lever components. Refer to Park Brake Lever Assembly Replacement in Park Brake.

Is the repair complete?

--

Go to Step 33

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13

Inspect the disc brake caliper mounting bolts for corrosion. Refer to Brake Caliper Inspection in Disc Brakes.

Are the sleeves or mounting bolts corroded?

--

Go to Step 14

Go to Step 15

14

Replace the mounting bolt sleeves and bolts as necessary.

Is the repair complete?

--

Go to Step 33

--

15
  1. Remove the caliper piston. Refer to the appropriate procedure:
    2. •  Front Brake Caliper Overhaul in Disc Brakes
    •  Rear Brake Caliper Overhaul in Disc Brakes
  2. Inspect the caliper bore and the piston for scoring, corrosion, plating damage or pitting.

Is there damage to the piston or caliper bore?

--

Go to Step 16

Go to Step 17

16

Replace the piston or the caliper as needed.

Is the repair complete?

--

Go to Step 33

--

17
  1. Inspect the brake pedal assembly for bent or misaligned components.
  2. Inspect the brake pedal for interference (binding) between the pedal and the booster input rod.

Is the brake pedal binding?

--

Go to Step 18

Go to Step 19

18
  1. Disassemble and realign or replace components as necessary.
  2. Replace the brake pedal. Refer to Brake Pedal Replacement .

Is the repair complete?

--

Go to Step 33

--

19

Inspect the brake pedal for interference with other components. Inspect the brake pedal area for the following conditions:

    • Loose or misaligned the trim panels
    • Loose components, wiring harnesses or aftermarket devices

Are there any loose or interfering components?

--

Go to Step 20

Go to Step 21

20

Realign or reposition components as necessary.

Is the repair complete?

--

Go to Step 33

--

21
    • Inspect for collapsed, dented, or bent brake pipes. Refer to Brake Fluid Leak .
    • Inspect the brake hoses for sharp kinks. Refer to Brake Fluid Leak .

Are the brake hoses or the brake pipes collapsed, bent, or kinked?

--

Go to Step 22

Go to Step 23

22

Reroute or replace the brake hoses or the brake pipes as necessary. Refer to the appropriate procedure:

    •  Brake Pipe Replacement

Is the repair complete?

--

Go to Step 33

--

23
  1. Remove the master cylinder reservoir cover.
  2. Rapidly apply the brake pedal 3 cm (1 in), observing the brake fluid in the reservoir.

Does the fluid surface in the forward reservoir show movement, or spouting?

--

Go to Step 24

Go to Step 25

24
  1. Install the master cylinder reservoir cover.
  2. Loosen the master cylinder mounting nuts 13 mm (½ in).
  3. Separate the master cylinder from the hydraulic brake booster.
  4. Apply the brake pedal 3 cm (1 in).

Does the booster output rod move?

--

Go to Step 25

Go to Step 26

25

Overhaul or replace the master cylinder. Refer to Master Cylinder Overhaul or Master Cylinder Replacement .

Is the repair complete?

--

Go to Step 33

--

26

Replace the vacuum brake booster. Refer to Power Vacuum Brake Booster Replacement .

Is the repair complete?

--

Go to Step 33

--

27
  1. Remove the master cylinder reservoir cover.
  2. Inspect the brake fluid for contamination. Refer to Brake Fluid and Brake Fluid Handling .

Is the brake fluid contaminated?

--

Go to Step 28

Go to Step 29

28
  1. Replace all of the rubber brake system components. Refer to the following procedures:
    2. •  Wheel Cylinder Overhaul in Drum Brakes
    •  Front Brake Caliper Overhaul in Disc Brakes
    •  Front Brake Caliper Overhaul in Disc Brakes
    •  Rear Brake Caliper Overhaul in Disc Brakes
  2. Flush the hydraulic brake system. Refer to Hydraulic Brake System Flushing .

Is the repair complete?

--

Go to Step 33

--

29

Inspect the master cylinder outlet ports for restricted passages. Refer to Hydraulic Brake System Bleeding .

Are the outlet ports restricted?

--

Go to Step 30

Go to Step 31

30
  1. Overhaul the master cylinder. Refer to Master Cylinder Overhaul .
  2. Flush the hydraulic brake system. Refer to Hydraulic Brake System Flushing .

Is the repair complete?

--

Go to Step 33

--

31

Inspect the brake pipes and the brake hoses for restricted passages. Refer to Hydraulic Brake System Flushing .

Inspect for the following conditions:

    • Low fluid or no fluid output
    • Spurting of fluid while pressing the brake pedal
    • Particles suspended in the fluid

Do any of the above conditions apply?

--

Go to Step 32

Go to Step 33

32
  1. Determine the area of the restriction. This will involve the disassembly of individual brake lines and checking for low fluid output.
  2. Flush the individual brake line or the brake hose.
  3. If the restriction cannot be removed, replace the brake hose or the brake pipe as necessary. Refer to the appropriate procedure:
  4. Flush the hydraulic brake system. Refer to Hydraulic Brake System Flushing .

Is the repair complete?

--

Go to Step 33

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33

Verify proper brake system operation.

Does the brake system operate properly?

--

System OK

Go to Hydraulic Brake Diagnostic System Check