Hummer H3. Manual — part 1334

Fig. 42: View Of Master Cylinder And Brake Pipes
Courtesy of GENERAL MOTORS CORP.

2. With all brake pipes installed securely to the master cylinder, loosen and separate the

left front brake pipe (4) from the left front port of the brake master cylinder.

3. Allow a small amount of brake fluid to gravity bleed from the open port of the master

cylinder.

4. Reconnect the brake pipe to the master cylinder port and tighten securely.

2007 Hummer H3

2007 BRAKES Hydraulic Brakes - H3

5. Have an assistant slowly depress the brake pedal fully and maintain steady pressure on

the pedal.

6. Loosen the same brake pipe to purge air from the open port of the master cylinder.

7. Tighten the brake pipe, then have the assistant slowly release the brake pedal.

8. Wait 15 seconds, then repeat steps 2.5-2.7 until all air is purged from the same port of

the master cylinder.

9. With the left front brake pipe (4) installed securely to the master cylinder, after all air

has been purged from the left front port of the master cylinder, loosen and separate the
right front brake pipe (3) from the master cylinder, then repeat steps 2.5-2.8.

10. Turn the ignition key to the ON position.

11. With the right front brake pipe (3) installed securely to the master cylinder, after all

air has been purged from the right front port of the master cylinder, loosen and
separate the left rear brake pipe (1) from the master cylinder, then repeat steps 2.5-2.8.

12. With the left rear brake pipe (1) installed securely to the master cylinder, after all air

has been purged from the left rear port of the master cylinder, loosen and separate the
right rear brake pipe (2) from the master cylinder, then repeat steps 2.5-2.8.

13. After completing the final master cylinder port bleeding procedure, ensure that all of

the brake pipe-to-master cylinder fittings are properly tightened.

14. Turn the ignition key to the OFF position. Depress the brake pedal 20 times.

3. Fill the brake master cylinder reservoir with Delco Supreme 11®, GM P/N 12377967

(Canadian P/N 992667) or equivalent DOT-3 brake fluid from a clean, sealed brake fluid
container. Ensure that the brake master cylinder reservoir remains at least half-full during
this bleeding procedure. Add fluid as needed to maintain the proper level.

Clean the outside of the reservoir on and around the reservoir cap prior to removing the cap
and diaphragm.

4. Install a proper box-end wrench onto the RIGHT REAR wheel hydraulic circuit bleeder

valve.

5. Install a transparent hose over the end of the bleeder valve.

6. Submerge the open end of the transparent hose into a transparent container partially filled

with Delco Supreme 11®, GM P/N 12377967 (Canadian P/N 992667) or equivalent DOT-
3 brake fluid from a clean, sealed brake fluid container.

7. Have an assistant turn the ignition ON, then partially apply and hold the brake pedal. DO

NOT pump the brake pedal. Fluid will flow when the bleed valves are opened.

8. Loosen the bleeder valve to purge air from the wheel hydraulic circuit.

2007 Hummer H3

2007 BRAKES Hydraulic Brakes - H3

9. Tighten the bleeder valve, then have the assistant slowly release the brake pedal.

10. Wait 15 seconds, then repeat steps 7-9 until all air is purged from the same wheel hydraulic

circuit.

11. With the right rear wheel hydraulic circuit bleeder valve tightened securely, after all air has

been purged from the right rear hydraulic circuit, install a proper box-end wrench onto the
LEFT REAR wheel hydraulic circuit bleeder valve.

12. Install a transparent hose over the end of the bleeder valve, then repeat steps 6-10.

13. Turn the ignition OFF. The assistant will now have to pump the brake pedal for fluid to

flow from open bleed valves.

14. With the left rear wheel hydraulic circuit bleeder valve tightened securely, after all air has

been purged from the left rear hydraulic circuit, install a proper box-end wrench onto the
RIGHT FRONT wheel hydraulic circuit bleeder valve.

15. Install a transparent hose over the end of the bleeder valve, then repeat steps 7-11.

16. With the right front wheel hydraulic circuit bleeder valve tightened securely, after all air has

been purged from the right front hydraulic circuit, install a proper box-end wrench onto the
LEFT FRONT wheel hydraulic circuit bleeder valve.

17. Install a transparent hose over the end of the bleeder valve, then repeat steps 7-11.

18. After completing the final wheel hydraulic circuit bleeding procedure, ensure that each of

the 4 wheel hydraulic circuit bleeder valves are properly tightened.

19. Fill the brake master cylinder reservoir to the maximum-fill level with Delco Supreme 11®,

GM P/N 12377967 (Canadian P/N 992667) or equivalent DOT-3 brake fluid from a clean,
sealed brake fluid container. Refer to Master Cylinder Reservoir Filling.

20. Slowly depress and release the brake pedal. Observe the feel of the brake pedal.

21. If the brake pedal feels spongy, repeat the bleeding procedure again. If the brake pedal still

feels spongy after repeating the bleeding procedure, perform the following steps:

1. Inspect the brake system for external leaks. Refer to Brake System External Leak

Inspection .

2. Pressure bleed the hydraulic brake system in order to purge any air that may still be

trapped in the system.

22. Turn the ignition key ON, with the engine OFF. Check to see if the brake system warning

lamp remains illuminated.

IMPORTANT: If the brake system warning lamp remains illuminated, DO

NOT allow the vehicle to be driven until it is diagnosed and
repaired.

2007 Hummer H3

2007 BRAKES Hydraulic Brakes - H3

23. If the brake system warning lamp remains illuminated, refer to Symptoms - Hydraulic

Brakes.

HYDRAULIC BRAKE SYSTEM BLEEDING (MANUAL WITH RPO BRM)

1. Place a clean shop cloth beneath the brake master cylinder to prevent brake fluid spills.

2. If you disconnected the brake pipes from the master cylinder, you must perform the

following steps:

1. Ensure that the brake master cylinder reservoir is full to the maximum-fill level. If

CAUTION: Refer to Brake Fluid Irritant Caution .

CAUTION: Refer to DOT 4 BRAKE FLUID CAUTION .

CAUTION: Do not remove the reservoir cap while depressing and

releasing the brake pedal. If the cap is removed while
depressing and releasing the brake pedal, pressurized brake
fluid being returned to the reservoir may leave the reservoir.
Personal injury or vehicle damage could result.

NOTE:

Refer to Brake Fluid Effects on Paint and Electrical Components
Notice .

NOTE:

When adding fluid to the brake master cylinder reservoir, use only
GM Vehicle Care Brake and Clutch Fluid Super DOT-4, GM P/N
88958860 (Canadian P/N 88901244) or equivalent DOT-4 brake fluid
from a clean, sealed container. This polyglycol brake fluid is
hygroscopic and absorbs moisture. Do not use fluid from an open
container that may be contaminated with water. Improper or
contaminated fluid could result in damage to the system
components.

NOTE:

Do Not allow the HBCi pump and motor to run more than 1 minute
continuously. Allow 2 minutes cool down time between pump run
times. Extended pump and motor run time could create excessive
heat and damage the pump and motor assembly.

2007 Hummer H3

2007 BRAKES Hydraulic Brakes - H3