GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

1

Was the Hydraulic Brake Diagnostic System Check performed?

Go to Step 2

Go to Hydraulic Brake Diagnostic System Check

2

Inspect the hydraulic brake system for leaks.

Are there any leaks?

Go to Step 3

Go to Step 5

3

  1. Tighten the brake hose or pipe fittings to specifications.
  2. Start the engine.
  3. Press the brake pedal several times.
  4. Turn OFF the engine.
  5. Inspect the hydraulic brake system for leaks.

Does the leak still exist?

Go to Step 4

Go to Hydraulic Brake Diagnostic System Check

4

Replace the applicable brake hose or the brake pipe.

Is the repair complete?

Go to Hydraulic Brake Diagnostic System Check

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5

Inspect the brake pads for the following:

    • Excessive wear
    • Uneven wear
    • Abuse
    • Glazing
    • Contaminated lining material
    • Incorrect lining material

Refer to Brake Pad Inspection in Disc Brakes.

Do any of the above conditions exist?

Go to Step 6

Go to Step 7

6

Replace the brake pads as necessary. Refer to Brake Pads Replacement in Disc Brakes.

Is the repair complete?

Go to Hydraulic Brake Diagnostic System Check

--

7

Inspect the following brake caliper assembly components for excessive wear or corrosion:

    • Mounting bolts
    • Boots
    • Steering knuckle
    • Brake caliper
    • Brake caliper pistons

Are any of the above components corroded or binding?

Go to Step 8

Go to Step 9

8

Repair or replace the brake calipers. Refer to the applicable repair procedures.

    • For the FRONT brake calipers, refer to Front Brake Caliper Overhaul or Front Brake Caliper Replacement in Disc Brakes.
    • For the REAR brake calipers, refer to Rear Brake Caliper Replacement in Disc Brakes.

Is the repair complete?

Go to Hydraulic Brake Diagnostic System Check

--

9

Inspect the brake components for loose, missing or broken components. Refer to Brake Pad Inspection in Disc Brakes.

Are there loose, missing or broken brake components?

Go to Step 10

Go to Step 11

10

Repair or replace the components as necessary.

Is the repair complete?

Go to Hydraulic Brake Diagnostic System Check

--

11

Inspect the proportioning valve or combination valve for leakage.

Is the proportioning valve or combination valve leaking?

Go to Step 12

Go to Step 13

12

Replace the proportioning valve or combination valve. Refer to Proportioning Valve Replacement or Combination Valve Replacement .

Is the repair complete?

Go to Hydraulic Brake Diagnostic System Check

--

13

  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 14

Go to Step 15

14

Repair or replace components as necessary.

Is the repair complete?

Go to Hydraulic Brake Diagnostic System Check

--

15

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

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

Are there any loose or interfering components?

Go to Step 16

Go to Step 17

16

Repair or replace the components as necessary.

Is the repair complete?

Go to Hydraulic Brake Diagnostic System Check

--

17

    • Check for collapsed, damaged, or bent brake pipes.
    • Check the brake hoses for kinks.

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

Go to Step 18

Go to Step 19

18

Repair or replace the brake hoses or pipes as necessary.

Is the repair complete?

Go to Hydraulic Brake Diagnostic System Check

--

19

  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 20

Go to Step 21

20

  1. Install the master cylinder reservoir cover.
  2. Loosen the master cylinder mounting nuts 13 mm (0.50 in).
  3. Separate the master cylinder from the vacuum brake booster.
  4. Apply the brake pedal 3 cm (1 in).

Does the booster output rod move?

Go to Step 21

Go to Step 22

21

Replace the master cylinder. Refer to Master Cylinder Replacement .

Is the repair complete?

Go to Hydraulic Brake Diagnostic System Check

--

22

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

Is the repair complete?

Go to Hydraulic Brake Diagnostic System Check

--

23

  1. Remove the master cylinder reservoir cover.
  2. Inspect the brake fluid for contamination.

Is the brake fluid contaminated?

Go to Step 24

Go to Step 25

24

Replace all of the hydraulic brake system rubber components.

  1. Flush the hydraulic brake system. Refer to Hydraulic Brake System Flushing .
  2. Replace the master cylinder. Refer to Master Cylinder Replacement .
  3. Replace the front brake hoses. Refer to Front Brake Hose Replacement .
  4. Replace the rear brake hoses. Refer to Rear Brake Hose Replacement .
  5. Repair or replace the FRONT brake calipers. Refer to Front Brake Caliper Overhaul or Front Brake Caliper Replacement in Disc Brakes.
  6. Repair or replace the REAR brake calipers. Refer to Rear Brake Caliper Overhaul or Rear Brake Caliper Replacement in Disc Brakes.
  7. Flush the hydraulic brake system. Refer to Hydraulic Brake System Flushing .

Is the repair complete?

Go to Hydraulic Brake Diagnostic System Check

--

25

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

Are the outlet ports restricted?

Go to Step 26

Go to Step 27

26

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

Is the repair complete?

Go to Hydraulic Brake Diagnostic System Check

--

27

Check the brake pipes and the brake hoses for restricted passages.

Check for the following:

    • 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 28

Go to Hydraulic Brake Diagnostic System Check

28

  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 pipe or the brake hose.
  3. If the restriction cannot be removed, replace the applicable brake hose or the brake pipe.
  4. Flush the hydraulic brake system. Refer to Hydraulic Brake System Flushing .

Is the repair complete?

Go to Hydraulic Brake Diagnostic System Check

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