Hydraulic Brake System Bleeding (Pressure)
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Hydraulic Brake System Bleeding (Pressure)
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Refer to
Brake Fluid Irritant Warning
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Refer to
Brake Fluid Effects on Paint and Electrical Components Caution
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1.
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Place a clean shop cloth beneath the brake master cylinder to prevent brake fluid spills.
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2.
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With the ignition OFF and the brakes cool, apply the brakes 3-5 times, or until the brake pedal effort increases significantly, in order to deplete the brake booster power reserve.
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3.
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If you have performed a brake master cylinder bench bleeding on this vehicle, or if you disconnected the brake pipes from the master cylinder, you must perform the following steps:
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3.1.
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Ensure that the brake master cylinder reservoir is full to the maximum fill level. If necessary add GM approved brake fluid from a clean sealed brake fluid container. Refer to
Fluid and Lubricant Recommendations
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If removal of the reservoir cap and diaphragm is necessary, clean the outside of the reservoir on and around the cap prior to removal.
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3.2.
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With the rear brake pipe installed securely to the master cylinder, loosen and separate the front brake pipe from the front port of the brake master cylinder.
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3.3.
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Allow a small amount of brake fluid to gravity bleed from the open port of the master cylinder.
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3.4.
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Reconnect the brake pipe to the master cylinder port and tighten securely.
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3.5.
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Have an assistant slowly depress the brake pedal fully and maintain steady pressure on the pedal.
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3.6.
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Loosen the same brake pipe to purge air from the open port of the master cylinder.
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3.7.
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Tighten the brake pipe, then have the assistant slowly release the brake pedal.
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3.8.
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Wait for 15 seconds. Then repeat steps 3.3-3.7 until all air is purged from the same port of the master cylinder.
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3.9.
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After all air has been purged from the front port of the master cylinder and with the front brake pipe reassembled to the master cylinder, loosen and separate the rear brake pipe from the master cylinder. Then repeat steps 3.3-3.8.
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3.10.
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After completing the final master cylinder port bleeding procedure, ensure that both of the brake pipe-to-master cylinder fittings are properly tightened.
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4.
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Note
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Clean the outside of the reservoir on and around the reservoir cap prior to removing the cap and diaphragm.
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Fill the brake master cylinder reservoir to the maximum-fill level with GM approved brake fluid from a clean, sealed brake fluid container. Refer to
Master Cylinder Reservoir Filling
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5.
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Install an appropriate brake pressure bleeder adapter to the brake master cylinder reservoir.
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6.
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Check the brake fluid level in the brake pressure bleeder. Add GM approved brake fluid from a clean, sealed brake fluid container as necessary to bring the level to approximately the half-full point.
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7.
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Connect the brake pressure bleeder to the brake pressure bleeder adapter.
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8.
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Charge the brake pressure bleeder air tank to 175-205 kPa (25-30 psi).
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9.
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Open the brake pressure bleeder fluid tank valve to allow pressurized brake fluid to enter the brake system.
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10.
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Wait approximately 30 seconds, then inspect the entire hydraulic brake system in order to ensure that there are no existing external brake fluid leaks.
Any brake fluid leaks identified require repair prior to completing this procedure.
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11.
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Install a proper box-end wrench onto the RIGHT REAR wheel hydraulic circuit bleeder valve.
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12.
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Install a transparent hose over the end of the bleeder valve.
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13.
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Submerge the open end of the transparent hose into a transparent container partially filled with GM approved brake fluid from a clean, sealed brake fluid container.
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14.
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Loosen the bleeder valve to purge air from the wheel hydraulic circuit. Allow fluid to flow until air bubbles stop flowing from the bleeder, then tighten the bleeder valve.
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15.
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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 FRONT wheel hydraulic circuit bleeder valve.
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16.
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Install a transparent hose over the end of the bleeder valve, then repeat steps 13-14.
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17.
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With the left front wheel hydraulic circuit bleeder valve tightened securely, after all air has been purged from the left front hydraulic circuit, install a proper box-end wrench onto the LEFT REAR wheel hydraulic circuit bleeder valve.
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18.
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Install a transparent hose over the end of the bleeder valve, then repeat steps 13-14.
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19.
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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
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20.
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Install a transparent hose over the end of the bleeder valve, then repeat steps 13-14.
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21.
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After completing the final wheel hydraulic circuit bleeding procedure, ensure that each of the 4 wheel hydraulic circuit bleeder valves are properly tightened.
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22.
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Close the brake pressure bleeder fluid tank valve, then disconnect the brake pressure bleeder from the brake pressure bleeder adapter.
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23.
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Remove the brake pressure bleeder adapter from the brake master cylinder reservoir.
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24.
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Fill the brake master cylinder reservoir to the maximum-fill level with GM approved brake fluid from a clean, sealed brake fluid container.
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25.
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Slowly depress and release the brake pedal. Observe the feel of the brake pedal.
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26.
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If the brake pedal feels spongy, perform the following steps:
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26.2.
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Using a scan tool, perform the antilock brake system automated bleeding procedure to remove any air that may have been trapped in the brake pressure modulator valve (BPMV). Refer to
Antilock Brake System Automated Bleed
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27.
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Turn the ignition key ON, with the engine OFF. Check to see if the brake system warning lamp remains illuminated.
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28.
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Note
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DO NOT allow the vehicle to be driven until it is diagnosed and repaired.
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If the brake system warning lamp remains illuminated, refer to
Diagnostic Starting Point - Vehicle
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