Hydraulic Brake System Buick Enclave I

Fastener Tightening Specifications

Fastener Tightening Specifications

Brake System Specifications

Brake System Specifications

Scheme 1

Diagnostic Code Index

DIAGNOSTIC CODE INDEX

Diagnostic Instructions

1. Perform the «Diagnostic System Check - Vehicle»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Diagnostic Fault Information

Circuit/System Description

The brake fluid level switch monitors the level of brake fluid in the master cylinder. When the instrument panel cluster (IPC) sees the brake fluid level switch input closed, it turns ON the Red Brake Warning indicator and sends a serial data message to the electronic brake control module (EBCM) that the brake fluid level is low.

Conditions for Running the DTC

Ignition ON.

Conditions for Setting the DTC

1. Low brake fluid is detected.
2. A short to ground exists on the signal circuit.

Action Taken When the DTC Sets

1. The EBCM disables the antilock brake system (ABS)/traction control system (TCS) dynamic rear proportion (DRP) and vehicle stability enhancement system (VSES).
2. A DIC message and/or a warning indicator may be displayed.

Conditions for Clearing the DTC

1. The condition for the DTC is no longer present.
2. The EBCM clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

Reference Information

Schematic Reference

Hydraulic Brake Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Brake Warning System Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Inspect for proper brake fluid level, the fluid level should be at or above the proper level. If low, refer to «Brake Fluid Loss»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system__brake-fluid-loss) .
2. Ignition ON, observe the scan tool IPC Brake Fluid parameter. The reading should be OK.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the brake fluid level switch.
2. Test for less than 10 ohm between the ground circuit terminal A and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
3. Ignition ON, verify the scan tool IPC Brake Fluid parameter is Ok. If not the specified value, test the signal circuit for a short to ground. If the circuit tests normal, replace the IPC.
4. Install a 3A fused jumper wire between the signal circuit terminal B and ground. Verify the scan tool IPC Brake Fluid parameter is Low. If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the IPC.
5. If all circuits test normal, test or replace the brake fluid level switch.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Brake Fluid Level Indicator Switch Replacement»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system)
2. «Control Module References»(/buick/enclave/i-2007-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for IPC replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The power brake booster vacuum sensor monitors the vacuum level in the power brake booster. When the electronic brake control module (EBCM) detects the vacuum level is low a DTC is set.

The engine is running.

Low or no vacuum is detected in the power brake booster after start-up.

1. The condition for the DTC is no longer present.
2. The EBCM clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

Schematic Reference

Hydraulic Brake Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Brake Assist System Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

1. Verify that a vacuum leak is not present, refer to «Brake Assist System Diagnosis»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system__brake-assist-system-diagnosis) .
2. Verify that DTC C1100 is not set. If DTC is set, refer to «DTC C1100»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system) .

1. Perform the «Diagnostic System Check - Vehicle»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The electronic brake control module (EBCM) provides a 5-volt reference to the brake booster vacuum sensor. The brake booster vacuum sensor converts the change in vacuum levels in the brake booster into a signal voltage ranging from 0.13-3.30 volts and is monitored by EBCM.

Ignition ON.

The brake booster sensor signal voltage is not within 0.13-3.30 volts for more than 1 second.

1. The condition for the DTC is no longer present.
2. The EBCM clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

Schematic Reference

Hydraulic Brake Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Brake Assist System Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

1. Ignition OFF, disconnect the harness connector at the brake booster vacuum sensor.
2. Wait for 60 seconds, test for less than 11 ohms between the low reference circuit terminal 2 and ground. If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the EBCM.
3. Ignition ON, test for 4.8-5.2 V between the 5 V reference circuit terminal 3 and ground. If less than the specified range, test the 5 V reference circuit for an open/high resistance. If the circuit tests normal, replace the replace the EBCM. If greater than the specified range, test the 5 V reference circuit for a short to B+. If the circuit tests normal, replace the EBCM.
4. Ignition ON, test for 4.8-5.2 V between the 5 V reference circuit terminal 3 and the signal circuit terminal 1. If less than the specified range, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the EBCM. If greater than the specified range, test the signal circuit for a short to B+. If the circuit tests normal, replace the EBCM.
5. Ignition OFF, disconnect the harness connector at the EBCM.
6. Test for infinite resistance between the signal circuit terminal 1 and ground. If not the specified value, test the signal circuit for a short to ground.
7. If all circuits test normal, test or replace the brake booster vacuum sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Power Brake Booster Vacuum Sensor Replacement»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system)
2. «Control Module References»(/buick/enclave/i-2007-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for EBCM replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The engine control module (ECM) monitors the control circuit of the brake booster pump relay. The ECM supplies ground through the pump relay control circuit which then supplies B+ voltage to actuate the brake booster pump. B+ voltage is supplied at all times to the coil side of the pump relay.

P258A, P258C, P258D

Ignition ON.

P258B

1. Engine Running
2. Vacuum pump is activated for greater than 1.6 seconds.

P258A, P258C

The ECM detects an open/high resistance on the relay coil control circuit.

P258B

The ECM detects an excessive difference in vacuum levels between the power brake booster and the manifold absolute pressure (MAP).

P258D

The ECM detects a short to voltage on the relay control circuit.

DTC P258A, P258B, P258C, P258D are Type B DTCs.

DTC P258A, P258B, P258C, P258D are Type B DTCs.

Schematic Reference

Hydraulic Brake Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Brake Booster Vacuum Assist Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

1. Verify that a vacuum leak is not present, refer to «Brake System Vacuum Source Test»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system__brake-system-vacuum-source-test)
2. Ignition ON, command the relay ON and OFF with a scan tool. Observe to verify that the vacuum relay and motor turns ON and OFF with each command.

1. Ignition OFF, disconnect the vacuum pump relay.
2. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 87 and ground. If the test lamp illuminates, test the control circuit for a short to voltage.
3. Verify that a test lamp illuminates between the B+ circuit terminals listed below and ground. Terminal 30 Terminal 86 If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test or replace the relay.
4. Verify that a test lamp does not illuminate between the control circuit terminal 85 and ground. If the test lamp illuminates, test the control circuit for a short to voltage.
5. Disconnect the harness connector at the vacuum pump.
6. Test for less than 2 ohms between the vacuum pump ground circuit terminal 2 and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
7. Connect the harness connector at the vacuum pump.
8. Connect a 20A fused jumper wire between the B+ circuit terminal 30 and the control circuit terminal 87. Verify the vacuum pump is activated. If the vacuum pump does not activate, test the control circuit for a short ground or an open/high resistance. If the circuit tests normal, test or replace the vacuum pump.
9. Ignition OFF, test for infinite resistance between the control circuit terminal 85 and ground. If less than the specified value, test the control circuit for a short to ground. If the circuit tests normal, replace the ECM.
10. Disconnect the X1 harness connector at the ECM.
11. Test for less than 2 ohms between the control circuit terminal 85 at the relay cavity and terminal 18 at the ECM harness connector. If greater than the specified range, test the control circuit for an open/high resistance.
12. If all circuits test normal, replace the brake booster pump relay. If the DTC resets, replace the power brake booster vacuum pump.

Component Testing

1. Ignition OFF, disconnect the vacuum pump relay.
2. Test for 60-180 ohms between terminals 85 and 86. If the resistance is not within the specified range, replace the relay.
3. Test for infinite resistance between the following terminals: 30 and 85 30 and 87 30 and 86 86 and 87 If not the specified value, replace the relay.
4. Install a 30A fused jumper wire between relay terminal 86 and B+. Install a jumper wire between relay terminal 85 and ground.
5. Test for less than 2 ohms between terminals 30 and 87. If greater than the specified range, replace the relay.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Relay Replacement (Within an Electrical Center)»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions__relay-replacement-within-an-electrical-center) , «Relay Replacement (Attached to Wire Harness)»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions)
2. «Power Brake Booster Auxiliary Pump Replacement»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system)
3. «Control Module References»(/buick/enclave/i-2007-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for ECM replacement, setup, and programming

Symptoms - Hydraulic Brakes

Visual/Physical Inspection

1. Inspect for aftermarket devices which could affect the operation of the Hydraulic Brake System. Refer to «Checking Aftermarket Accessories»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__checking-aftermarket-accessories) .
2. Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.

Intermittent

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections .

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom

1. «Brake Warning Indicator Malfunction (Without UJ1)»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system)
2. «Brake Pulsation»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system__brake-pulsation)
3. «Brake System Noise»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system__brake-system-noise)
4. «Braking Action Uneven - Pulls to One Side»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system)
5. «Braking Action Uneven - Front to Rear»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system)
6. «Brake Pedal Excessive Travel»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system__brake-pedal-excessive-travel)
7. «Brake Pedal Excessive Effort»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system__brake-pedal-excessive-effort)
8. «Brakes Drag»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system__brakes-drag)
9. «Brake Fluid Loss»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system__brake-fluid-loss)
10. «Hydraulic Brake System Diagnosis»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system)
11. «Brake Assist System Diagnosis»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system__brake-assist-system-diagnosis)

1. Perform the «Diagnostic System Check - Vehicle»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The instrument panel cluster (IPC) sees the brake fluid level switch input opens and illuminates the Red Brake Warning indicator. The body control module (BCM) sees the park brake switch input grounded, it sends a serial data message to the IPC requesting illumination of the Red Brake Warning indicator.

Schematic Reference

Hydraulic Brake Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Brake Warning System Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

1. Verify the park brake is released and the brake fluid is at or above the proper level. If low, refer to «Brake Fluid Loss»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system__brake-fluid-loss) .
2. Command the IPC display test with a scan tool, the warning indicator should turn ON. If the red brake warning indicator does not illuminate, replace the IPC.
3. Ignition ON, observe the scan tool BCM Park Brake Switch parameter while applying and releasing the park brake. The parameter should cycle between Applied and Release. If the parameter does not cycle between the specified values, refer to Park Brake Switch Malfunction.
4. Observe the scan tool IPC Brake Fluid parameter. The reading should be OK. If not the specified value, refer to Brake Fluid Level Switch Malfunction.

Park Brake Switch Malfunction

1. Ignition OFF, disconnect the harness connector at the park brake switch.
2. Ignition ON, verify the scan tool BCM Park Brake Switch parameter is Released. If not the specified value, test the signal circuit terminal A for a short to ground. If the circuit tests normal, replace the BCM.
3. Install a 3A fused jumper wire between the signal circuit terminal A and ground. Verify the scan tool BCM Park Brake Switch parameter is Applied. If not the specified value, test the signal circuit for a short to voltage or an open/high resistance.
4. If all circuits test normal, test or replace the park brake switch.

Brake Fluid Level Switch Malfunction

1. Ignition OFF, disconnect the harness connector at the brake fluid level switch.
2. Test for less than 1 ohm between the ground circuit terminal A and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
3. Ignition ON, verify the scan tool IPC Brake Fluid parameter is Ok. If not the specified value, test the signal circuit for a short to ground. If the circuit tests normal, replace the IPC.
4. Install a 3A fused jumper wire between the signal circuit terminal B and ground. Verify the scan tool IPC Brake Fluid parameter is Low. If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the IPC.
5. If all circuits test normal, test or replace the brake fluid level switch.

Park Brake Switch Malfunction

1. Ignition OFF, disconnect the harness connector at the park brake switch.
2. Test for infinite resistance between the signal terminal A and ground with the park brake released. If less than the specified value, replace the park brake switch.
3. Test for less than 1 ohm between the signal terminal A and ground with the park brake applied. If greater than the specified range, replace the park brake switch.

Brake Fluid Level Switch Malfunction

1. Ignition OFF, disconnect the harness connector at the brake fluid level switch.
2. Test for infinite resistance between the ground terminal A and the signal terminal B. If less than the specified value, replace the brake fluid level switch.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Brake Fluid Level Indicator Switch Replacement»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system)
2. «Parking Brake Indicator Switch Replacement»(/buick/enclave/i-2007-2013/remont/parking-brake-system/#parking-brake-system)
3. «Control Module References»(/buick/enclave/i-2007-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM and IPC replacement, setup, and programming

Brake Pulsation

Brake Pulsation

Brake System Noise

Brake System Noise

Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. 4 Suspension components that are not operating properly may cause a disturbance to the vehicle during application of the brake system.
2. 5 Steering components that are not operating properly may cause a disturbance to the vehicle during application of the brake system.

Braking Action Uneven - Pulls to One Side

Test Descriptions

The number below refers to the step number on the diagnostic table.

1. 4 Suspension components that are not operating properly may cause a disturbance to the vehicle during application of the brake system.

Braking Action Uneven - Front to Rear

Brake Pedal Excessive Travel

Brake Pedal Excessive Travel

Brake Pedal Excessive Effort

Brake Pedal Excessive Effort

Brakes Drag

Brakes Drag

Brake System Slow Release

Brake System Slow Release

Brake Fluid Loss

Brake Fluid Loss

The numbers below refer to the step numbers on the diagnostic table.

1. 9 Lubricant leaks from non-brake system components may come in contact with and contaminate brake system components.
2. 10 Lubricant leaks from non-brake system components may come in contact with and contaminate brake system components.
3. 12 Disc brake rotor shields/backing plates that come in contact with disc brake rotors may cause brake system noise.

1. 15 Disc brake rotor thickness variation that exceeds the maximum acceptable level can cause brake pulsation.

1. 19 Disc brake rotor thickness variation that exceeds the maximum acceptable level can cause brake pulsation.

1. 22 Disc brake rotor assembled lateral runout (LRO) that exceeds the maximum acceptable level can lead to thickness variation.

Disc Brake System Diagnosis

Hydraulic Brake System Diagnosis

Brake Assist System Diagnosis

Brake Assist System Diagnosis

Preliminary Inspections

1. Visually inspect easily accessible brake system components for obvious damage and/or leaks which may indicate that the vehicle should not be driven until further inspections have been completed.
2. Inspect the brake master cylinder reservoir fluid level and adjust only if necessary for brake system road testing. Refer to «Master Cylinder Reservoir Filling»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system__master-cylinder-reservoir-filling) .
3. Inspect the tire inflation pressures and adjust as necessary.
4. Inspect the tire tread patterns to ensure that they are the same or very similar, especially per axle.
5. Ensure that the vehicle is not loaded unevenly prior to brake system road testing.

Road Testing Procedure

1. Start the engine and allow it to idle.
2. Check to see if the brake system warning lamp remains illuminated.
3. If the brake system warning lamp remains illuminated, DO NOT proceed to test drive the vehicle until it is diagnosed and repaired. Refer to «Symptoms - Hydraulic Brakes»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system__symptoms-hydraulic-brakes) .
4. Select a smooth, dry, clean and level road or large lot that is as free of traffic and obstacles as possible for brake system low speed road testing.
5. With the transmission in PARK, lightly apply the brake pedal. Observe both the pedal feel and the pedal travel.
6. If the brake pedal apply felt spongy, or the pedal travel was excessive, DO NOT drive the vehicle until it is repaired.
7. If the brake pedal apply did not feel spongy and the pedal travel was not excessive, proceed to step 8.
8. Release and apply the brakes.
9. While continuing to apply the brakes, shift the transmission into DRIVE, release the brakes and allow the engine to idle the vehicle away from the stopped position. Observe for a slow release of the brake system.
10. With the aid of an assistant to observe the vehicle's performance from outside of the vehicle, drive the vehicle at a low speed and lightly apply the brakes while driving past the assistant. Have the assistant observe for brake system noise from the side of the vehicle closest to them, while you observe both the pedal effort and the pedal travel.
11. If the brake pedal apply effort was excessive, or the pedal travel was excessive, DO NOT continue to test drive the vehicle until it is repaired.
12. If the brake pedal apply effort was not excessive and the pedal travel was not excessive, proceed to step 13.
13. Drive the vehicle in the opposite direction, at the same low speed and lightly apply the brakes while driving past the assistant. Have the assistant observe for brake system noise from the side of the vehicle closest to him.
14. Drive the vehicle at a low speed and shift the transmission into NEUTRAL without applying the brakes. Observe for a rapid deceleration in vehicle speed, indicating possible brake drag.
15. Select a smooth, dry, clean and level road that is as free of heavy traffic as possible for brake system moderate speed road testing.
16. Drive the vehicle at a moderate speed. Observe for a pull and/or incorrect tracking of the vehicle without the brakes applied.
17. While continuing to drive the vehicle at a moderate speed, perform several light applies of the brakes. Observe the pedal effort and the pedal travel, observe for brake system noise, pulsation and/or brake drag.
18. If the brake pedal apply effort was excessive, or the pedal travel was excessive, DO NOT continue to test drive the vehicle until it is repaired.
19. If the brake pedal apply effort was not excessive and the pedal travel was not excessive, proceed to step 20.
20. While continuing to drive the vehicle at a moderate speed, perform several moderate applies of the brakes. Observe the pedal effort and the pedal travel, observe for brake system pulsation and/or uneven braking action - either side to side, or front to rear. A small amount of vehicle front end dip is expected during a moderate apply of the brakes.
21. If the brake pedal apply effort was excessive, or the pedal travel was excessive, DO NOT continue to test drive the vehicle until it is repaired.

Brake Pedal Travel Measurement and Inspection

Special Tools

J 28662 Brake Pedal Effort Gauge

1. With the ignition OFF and the brakes cool, apply the brakes 3-5 times, or until the brake pedal becomes firm, in order to deplete the brake booster power reserve.
2. Install the J 28662 brake pedal effort gauge to the brake pedal.
3. Measure and record the distance (1) from the brake pedal to the rim of the steering wheel; note the points of measurement.
4. Apply and maintain the brakes with 445 N (100 lb) of force to the brake pedal, as indicated on the J 28662 brake pedal effort gauge.
5. While maintaining 445 N (100 lb) of force to the brake pedal, measure and record the distance (2) from the same point on the brake pedal to the same point on the rim of the steering wheel.
6. Release the brakes and repeat steps 4 and 5 to obtain a second measurement. After obtaining a second measurement, proceed to step 7.
7. Average the first and second measurements recorded during the two applies of the brakes.
8. Subtract the initial measurement, unapplied (1), from the averaged, applied measurement (2) to obtain the brake pedal travel distance. Specification Maximum brake pedal travel (measured with the ignition OFF, brake booster power assist depleted, and the brakes cool): 45 mm (1.77 in)

Brake System Vacuum Source Test

1. Disconnect the engine vacuum hose from the vacuum brake booster check valve.
2. Install a vacuum gauge to the engine vacuum hose.
3. Start the engine and allow the engine to idle until normal operating temperatures are reached.
4. With the vehicle in PARK, the engine idling, and the air conditioning (A/C) system OFF, check to see if the engine vacuum reading is within the specified normal engine vacuum range. Specification 47-68 kPa (14-20 in Hg)
5. Turn the ignition OFF.
6. If the engine vacuum reading was within the specified normal range, proceed to step 10.
7. If the engine vacuum reading was NOT within the specified normal range, inspect the engine vacuum hose for the following conditions: Loose connection to the engine Collapse, deformation or contamination Cracks, cuts, dry-rot
8. If any of these conditions were found with the engine vacuum hose, replace the hose, then repeat steps 2-4.
9. If none of these conditions were found with the engine vacuum hose, then there is an engine vacuum source problem, check the engine vacuum system.
10. Remove the vacuum brake booster check valve from the booster.
11. Install the check valve to the engine vacuum hose.
12. Install the vacuum gauge to the check valve.
13. Start the engine and allow the engine to idle in PARK with the A/C system OFF, until normal operating temperatures are reached.
14. Turn the ignition OFF.
15. Check to see if the engine vacuum reading is maintained within the specified normal engine vacuum range. Specification 47-68 kPa (14-20 in Hg)
16. If the engine vacuum reading is maintained within the specified normal range, proceed to step 18.
17. If the engine vacuum reading is NOT maintained within the specified normal range, replace the brake booster check valve, then repeat steps 11-15.
18. Inspect the brake booster check valve grommet for the following conditions: Loose connection to the vacuum brake booster Deformation or contamination Cracks, cuts, dry-rot
19. If any of these conditions were found with the check valve grommet, replace the grommet.

Brake System External Leak Inspection

1. In order to inspect for external brake fluid leaks, first check the fluid level in the master cylinder. While a slight brake fluid level drop can be considered a normal condition due to brake lining wear, a very low level may indicate a brake fluid leak in the hydraulic system.
2. If the fluid level is abnormally low, adjust the brake fluid level. Refer to «Master Cylinder Reservoir Filling»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system__master-cylinder-reservoir-filling) .
3. Start the engine and allow it to idle.
4. Apply constant, moderate foot pressure to the brake pedal. If the brake pedal gradually falls away while under foot pressure, there may be a brake fluid leak.
5. Turn OFF the ignition.
6. Visually inspect the following brake system components for brake fluid leaks, excessive corrosion, and damage. Give particular attention to all brake pipe and flexible hose connections to ensure that there are not any slight brake fluid leaks - even though the brake pedal may feel firm and hold steady: Master cylinder brake pipe fittings All brake pipe connections Brake pipes Brake hoses and connections Brake calipers and/or wheel cylinders, if equipped
7. While slight dampness around the master cylinder reservoir can be considered acceptable, brake fluid leaking from any of the brake system components requires immediate attention. If any of these components exhibit signs of brake fluid leakage, repair or replace those components. After the repair or replacement, reinspect the hydraulic brake system to assure proper function.

Brake System Internal Leak Test

1. Start the engine and allow it to idle.
2. Apply light, steady pressure to the brake pedal. Observe both the brake pedal feel and travel.
3. Release the brakes and turn OFF the ignition.
4. If the brake pedal apply felt spongy, but the brake pedal travel was not excessive, perform the following steps: Inspect the brake system for external leaks. Refer to «Brake System External Leak Inspection»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system__brake-system-external-leak-inspection) . Pressure bleed the brake system in order to purge any air that may be trapped in the system. Refer to «Hydraulic Brake System Bleeding (Manual)»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system) , «Hydraulic Brake System Bleeding (Pressure)»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system) .
5. If the brake pedal apply did not feel spongy, but the brake pedal travel was excessive, perform the following steps: Loosen the master cylinder-to-brake power booster mounting nuts. Carefully pull the master cylinder away from the brake power booster just enough to inspect the mounting surface of the master cylinder. Inspect the master cylinder mounting surface at the primary piston (2) for brake fluid leaks.
6. If the master cylinder exhibits any leakage around the primary piston (2), then the primary piston primary seal (4) and/or secondary seal (3) is leaking and the master cylinder requires overhaul or replacement.
7. If the master cylinder primary piston (2) does not exhibit any leakage, pressure bleed the brake system. Refer to «Hydraulic Brake System Bleeding (Manual)»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system) , «Hydraulic Brake System Bleeding (Pressure)»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system) .
8. If the brake pedal apply did not feel spongy, and the brake pedal travel was initially steady and not excessive, but then gradually fell, then the master cylinder requires overhaul or replacement due to an internal leak past the secondary piston (1) from the secondary piston primary seal (6) or secondary seal (5).
9. If the brake pedal apply did not feel spongy, and the brake pedal travel was initially steady and not excessive, then fell slightly, then became steady again, then the brake pressure modulator valve (BPMV) may be leaking internally, and may require replacement.

Hydraulic Brake Component Operation Visual Inspection

1. With the tire and wheel assemblies removed and the brake rotors retained by wheel lug nuts, visually inspect the caliper piston dust boot (2) sealing area to ensure that there are no brake fluid leaks.
2. If any evidence of a brake fluid leak is present, the brake caliper requires overhaul or replacement.
3. While the brake system is at rest (4), observe the position of the caliper piston (1) in relation to the caliper housing.
4. Have an assistant apply and release the brake pedal several times while you observe the operation of the hydraulic brake caliper. Observe the caliper piston (1) for unrestricted and even movement during each apply of the brake system (5). Observe the caliper piston (1) for an unrestricted and even return motion during each release of the brake system (6).
5. If the caliper piston (1) did not exhibit unrestricted and even movement during brake system apply and/or release, the piston square seal (3) may be worn or damaged and the caliper may require overhaul or replacement.

Brake Pipe and Hose Inspection

1. Visually inspect all of the brake pipes for the following conditions: Kinks, improper routing, missing or damaged retainers Leaking fittings, excessive corrosion
2. If any of the brake pipes exhibited any of the conditions listed, then the identified pipe, or pipes, require replacement.
3. Ensure that the vehicle axles are properly supported at ride height in order to maintain the proper relationship of the flexible brake hoses to the chassis.
4. Visually inspect all of the flexible brake hoses for the following conditions: Kinks (1), improper routing, twists, chafing, missing or damaged retainers Leaking connections, cracking, dry-rot, blisters, bulges
5. If any of the flexible brake hoses exhibited any of the conditions listed, then the identified flexible brake hose, or hoses require replacement.
6. Squeeze the flexible brake hoses with firm finger pressure to check for soft spots (2), indicating an internal restriction. Check the entire length of each flexible brake hose.
7. If any of the flexible brake hoses were found to have soft spots (2), then the identified flexible brake hose, or hoses require replacement.

Brake Pedal Pushrod Inspection

1. Disconnect the brake pedal pushrod (1) from the brake pedal.
2. Inspect the brake pedal pushrod eyelet bushing (2), if equipped, for cracks and/or excessive wear.
3. Reposition the pedal pushrod boot (3) toward the front of the vehicle to expose as much of the pedal pushrod (1) as possible.
4. Inspect the brake pedal pushrod (1) for straightness.
5. If the brake pedal pushrod eyelet bushing (2) exhibited cracks and/or excessive wear, then the bushing requires replacement.
6. If the brake pedal pushrod (1) is not straight, then the pushrod requires replacement.
7. Return the pedal pushrod boot (3) to its original position on the pedal pushrod (1).
8. Connect the brake pedal pushrod (1) to the brake pedal.

Master Cylinder Reservoir Filling

1. Visually inspect the brake fluid level through the brake master cylinder reservoir.
2. If the brake fluid level is at or below the half-full point during routine fluid checks, the brake system should be inspected for wear and possible brake fluid leaks.
3. If the brake fluid level is at or below the half-full point during routine fluid checks, and an inspection of the brake system did not reveal wear or brake fluid leaks, the brake fluid may be topped-off up to the maximum-fill level.
4. If brake system service was just completed, the brake fluid may be topped-off up to the maximum-fill level.
5. If the brake fluid level is above the half-full point, adding brake fluid is not recommended under normal conditions.
6. If brake fluid is to be added to the master cylinder reservoir, clean the outside of the reservoir on and around the reservoir cap prior to removing the cap and diaphragm. Use only GM approved brake fluid from a clean, sealed brake fluid container.

Scheme 2

Master Cylinder Reservoir Replacement

Scheme 3

Master Cylinder Replacement

Master Cylinder Bench Bleeding

1. Secure the mounting flange of the brake master cylinder in a bench vise so that the rear of the primary piston is accessible.
2. Remove the master cylinder reservoir cap and diaphragm.
3. Install suitable fittings to the master cylinder ports that match the type of flare seat required and also provide for hose attachment.
4. Install transparent hoses to the fittings installed to the master cylinder ports, then route the hoses into the master cylinder reservoir.
5. Fill the master cylinder reservoir to at least the half-way point with GM approved brake fluid from a clean, sealed brake fluid container. Refer to «Master Cylinder Reservoir Filling»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system__master-cylinder-reservoir-filling) .
6. Ensure that the ends of the transparent hoses running into the master cylinder reservoir are fully submerged in the brake fluid.
7. Using a smooth, round-ended tool, depress and release the primary piston as far as it will travel, a depth of about 25 mm (1 in), several times. Observe the flow of fluid coming from the ports. As air is bled from the primary and secondary pistons, the effort required to depress the primary piston will increase and the amount of travel will decrease.
8. Continue to depress and release the primary piston until fluid flows freely from the ports with no evidence of air bubbles.
9. Remove the transparent hoses from the master cylinder reservoir.
10. Install the master cylinder reservoir cap and diaphragm.
11. Remove the fittings with the transparent hoses from the master cylinder ports. Wrap the master cylinder with a clean shop cloth to prevent brake fluid spills.
12. Remove the master cylinder from the vise.

Scheme 4

Brake Fluid Level Indicator Switch Replacement

Removal Procedure

1. Remove the left side instrument panel (I/P) insulator panel. Refer to «Instrument Panel Insulator Panel Replacement - Left Side (Enclave)»(/buick/enclave/i-2007-2013/remont/exteriorinterior-trim/#instrument-panel-trim-and-console-trim) , «Instrument Panel Insulator Panel Replacement - Left Side (Acadia)»(/buick/enclave/i-2007-2013/remont/exteriorinterior-trim/#instrument-panel-trim-and-console-trim) , «Instrument Panel Insulator Panel Replacement - Left Side (Traverse)»(/buick/enclave/i-2007-2013/remont/exteriorinterior-trim/#instrument-panel-trim-and-console-trim) .
2. Remove the driver knee bolster. Refer to «Driver Knee Bolster Replacement (Acadia)»(/buick/enclave/i-2007-2013/remont/exteriorinterior-trim/#instrument-panel-trim-and-console-trim) , «Driver Knee Bolster Replacement (Traverse)»(/buick/enclave/i-2007-2013/remont/exteriorinterior-trim/#instrument-panel-trim-and-console-trim) , «Driver Knee Bolster Replacement (Enclave)»(/buick/enclave/i-2007-2013/remont/exteriorinterior-trim/#instrument-panel-trim-and-console-trim) .
3. Remove the accelerator pedal position sensor. Refer to «Accelerator Pedal Position Sensor Replacement»(/buick/enclave/i-2007-2013/remont/testing-diagnostics/#engine-controlsfuel-36l-repair-instructions) .
4. Disconnect the brake pedal position sensor electrical connector (1).
5. Remove the 2 brake pedal bracket bolts (2).
6. Remove the brake pedal pushrod retainer (1).
7. Remove the brake pedal pushrod clevis pin.
8. Remove the intermediate steering shaft. Refer to «Intermediate Steering Shaft Replacement»(/buick/enclave/i-2007-2013/remont/steering-column-switches/#steering-wheel-and-steering-column) .
9. Remove the 4 vacuum booster nuts.
10. Position the vacuum brake booster and master cylinder assembly forward slightly to allow the brake pedal and bracket assembly to clear the booster studs.
11. Remove the brake pedal assembly.

Installation Procedure

1. Position the brake pedal assembly to the dash panel.
2. Position the vacuum brake booster and master cylinder assembly to the dash panel.
3. Install the 4 vacuum booster nuts. Tighten Tighten the nuts to 25 N.m (18 lb ft).
4. Position the brake pedal pushrod to the brake pedal.
5. Install the brake pedal pushrod clevis pin.
6. Install the brake pedal pushrod retainer (1).
7. Install the intermediate steering shaft. Refer to «Intermediate Steering Shaft Replacement»(/buick/enclave/i-2007-2013/remont/steering-column-switches/#steering-wheel-and-steering-column) .
8. Connect the brake pedal position sensor electrical connector (1).
9. Install the 2 brake pedal bracket bolts (2). Tighten Tighten the bolts to 22 N.m (16 lb ft).
10. Install the accelerator pedal position sensor. Refer to «Accelerator Pedal Position Sensor Replacement»(/buick/enclave/i-2007-2013/remont/testing-diagnostics/#engine-controlsfuel-36l-repair-instructions) .
11. Install the driver knee bolster. Refer to «Driver Knee Bolster Replacement (Acadia)»(/buick/enclave/i-2007-2013/remont/exteriorinterior-trim/#instrument-panel-trim-and-console-trim) , «Driver Knee Bolster Replacement (Traverse)»(/buick/enclave/i-2007-2013/remont/exteriorinterior-trim/#instrument-panel-trim-and-console-trim) , «Driver Knee Bolster Replacement (Enclave)»(/buick/enclave/i-2007-2013/remont/exteriorinterior-trim/#instrument-panel-trim-and-console-trim) .
12. Install the left side I/P insulator panel. Refer to «Instrument Panel Insulator Panel Replacement - Left Side (Enclave)»(/buick/enclave/i-2007-2013/remont/exteriorinterior-trim/#instrument-panel-trim-and-console-trim) , «Instrument Panel Insulator Panel Replacement - Left Side (Acadia)»(/buick/enclave/i-2007-2013/remont/exteriorinterior-trim/#instrument-panel-trim-and-console-trim) , «Instrument Panel Insulator Panel Replacement - Left Side (Traverse)»(/buick/enclave/i-2007-2013/remont/exteriorinterior-trim/#instrument-panel-trim-and-console-trim) .
13. Calibrate the brake pedal position sensor. Refer to «Brake Pedal Position Sensor Calibration»(/buick/enclave/i-2007-2013/remont/exterior-lights/#lighting-system__brake-pedal-position-sensor-calibration) .

Brake Pipe Replacement

Special Tools

J 45405 Pipe Flaring Tool Kit

1. Inspect the area of brake pipe to be repaired or replaced.
2. Release the brake pipe to be replaced from the retainers, as required.
3. Select an appropriate location to section the brake pipe, if necessary. Allow adequate clearance in order to maneuver the J 45405 Pipe Flaring Tool Kit. Avoid sectioning the brake pipe at bends or mounting points.
4. Using a string or wire, measure the length of the pipe to be replaced including all pipe bends.
5. Add to the measurement taken the appropriate additional length required for each flare to be created. Specification 6.35 mm (0.250 in) for 4.76 mm (3/16 in) diameter pipe 9.50 mm (0.374 in) for 6.35 mm (1/4 in) diameter pipe 12.67 mm (0.499 in) for 7.94 mm (5/16 in) diameter pipe
6. Using the pipe cutter included in the J 45405 Pipe Flaring Tool Kit , carefully cut the brake pipe squarely to the measured length.
7. Remove the sectioned brake pipe from the vehicle.
8. Select the appropriate size of brake pipe and tube nuts, as necessary. The brake pipe outside diameter determines brake pipe size.
9. Strip the nylon coating from the brake pipe end to be flared, if necessary. Select the appropriate blade on the coating stripping tool included in the J 45405 Pipe Flaring Tool Kit , by unthreading the blade block from the stripping tool and installing the block with the desired blade facing the tool rollers. Specification 6.35 mm (0.250 in) blade for 4.76 mm (3/16 in) diameter pipe 9.50 mm (0.374 in) blade for 6.35 mm (1/4 in) and 7.94 mm (5/16 in) diameter pipe Insert the brake pipe end to be flared into the stripping tool to the depth of the ledge on the tool rollers. While holding the brake pipe firmly against the stripping tool roller ledges, rotate the thumbwheel of the tool until the blade contacts the brake pipe coated surface. NOTE: Do not gouge the metal surface of the brake pipe. Rotate the stripping tool in a clockwise direction, ensuring that the brake pipe end remains against the tool roller ledges. After each successive revolution of the stripping tool, carefully rotate the thumbwheel of the tool clockwise, in order to continue stripping the coating from the brake pipe until the metal pipe surface is exposed. Loosen the thumbwheel of the tool and remove the brake pipe. NOTE: Ensure that all loose remnants of the nylon coating have been removed from the brake pipe. Inspect the stripped end of the brake pipe to ensure that the proper amount of coating has been removed. Specification 6.35 mm (0.250 in) for 4.76 mm (3/16 in) diameter pipe 9.50 mm (0.374 in) for 6.35 mm (1/4 in) and 7.94 mm (5/16 in) diameter pipe
10. Chamfer the inside and outside diameter of the pipe with the de-burring tool included in the J 45405 Pipe Flaring Tool Kit.
11. Install the tube nuts on the brake pipe, noting their orientation.
12. Clean the brake pipe and the J 45405 Pipe Flaring Tool Kit of lubricant, contaminants, and debris.
13. Loosen the die clamping screw of the J 45405 Pipe Flaring Tool Kit.
14. Select the corresponding die set and install the die halves into the die cage with the full, flat face of one die facing the clamping screw, and the counterbores of both dies facing the forming ram.
15. Place the flat face of an unused die (1) against the die halves in the clamping cage and hold firmly against the counterbored face of the dies.
16. Insert the prepared end of the pipe to be flared through the back of the dies until the pipe is seated against the flat surface of the unused die (1).
17. Remove the unused die (1).
18. Ensure that the rear of both dies are seated firmly against the enclosed end of the die cage.
19. Firmly hand tighten the clamping screw (2) against the dies.
20. Select the appropriate forming mandrel and place into the forming ram.
21. Rotate the hydraulic fluid control valve clockwise to the closed position.
22. Rotate the body of the J 45405 Pipe Flaring Tool Kit until it bottoms against the die cage.
23. While guiding the forming mandrel into the exposed end of pipe to be flared, operate the lever of the J 45405 Pipe Flaring Tool Kit until the forming mandrel bottoms against the clamping dies.
24. Rotate the hydraulic fluid control valve counterclockwise to the open position to allow the hydraulic forming ram to retract.
25. Insert the finishing cone into the forming ram.
26. Rotate the hydraulic fluid control valve clockwise to the closed position.
27. Rotate the body of the J 45405 Pipe Flaring Tool Kit until it bottoms against the die cage.
28. While guiding the finishing cone into the exposed end of pipe to be flared, operate the lever of the J 45405 Pipe Flaring Tool Kit until the finishing cone bottoms against the dies.
29. Rotate the hydraulic fluid control valve counterclockwise to the open position to allow the hydraulic forming ram to retract.
30. Loosen the die clamping screw and remove the dies and pipe.
31. If necessary, lightly tap the dies until the die halves separate.
32. Inspect the brake pipe flare for correct shape and diameter (a). Specification 6.74-7.10 mm (0.265-0.279 in) flare diameter for 4.76 mm (3/16 in) diameter pipe 8.57-9.27 mm (0.344-0.358 in) flare diameter for 6.35 mm (1/4 in) diameter pipe 10.42-10.79 mm (0.410-0.425 in) flare diameter for 7.94 mm (5/16 in) diameter pipe
33. If necessary, using the removed section of brake pipe as a template, shape the new pipe with a suitable brake pipe bending tool.
34. Install the pipe to the vehicle with the appropriate brake pipe unions, as required.
35. If previously released, secure the brake pipe to the retainers.
36. Bleed the hydraulic brake system. Refer to «Hydraulic Brake System Bleeding (Manual)»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system) , «Hydraulic Brake System Bleeding (Pressure)»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system) .
37. With the aid of an assistant, inspect the brake pipe flares for leaks by starting the engine and applying the brakes.

Scheme 5

Front Brake Hose Replacement

1. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#general-information__lifting-and-jacking-the-vehicle) .
2. Remove the tire and wheel assembly. Refer to «Tire and Wheel Removal and Installation»(/buick/enclave/i-2007-2013/remont/wheel-tire-system/#tires-and-wheels__tire-and-wheel-removal-and-installation) .
3. Remove any dirt or debris from the brake pipe fitting (1).
4. Using a backup wrench on the brake hose fitting, disconnect the brake pipe fitting. Cap the brake pipe fitting to prevent brake fluid loss and contamination.
5. Remove the brake hose bracket bolt (2).
6. Remove the brake hose fitting bolt (1).
7. Remove and discard the 2 brake hose fitting gaskets (2).
8. Remove the brake hose (3).

1. Assemble the brake hose fitting bolt (1) and 2 new brake hose fitting gaskets (2) to the brake hose (3).
2. Install the brake hose assembly to the caliper and tighten the brake hose fitting bolt to 50 N.m (37 lb ft).
3. Install the brake hose bracket bolt (2) and tighten to 9 N.m (80 lb in).
4. Using a backup wrench on the brake hose fitting, connect the brake pipe fitting (1) and tighten to 17 N.m (13 lb ft).
5. Bleed the hydraulic brake system. Refer to «Hydraulic Brake System Bleeding (Manual)»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system) , «Hydraulic Brake System Bleeding (Pressure)»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system) .
6. Install the tire and wheel assembly. Refer to «Tire and Wheel Removal and Installation»(/buick/enclave/i-2007-2013/remont/wheel-tire-system/#tires-and-wheels__tire-and-wheel-removal-and-installation) .

If hydraulic components were serviced on only one wheel hydraulic circuit, perform the following procedure.

Bleeding a Single Hydraulic Brake Circuit

1. 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.
2. Place a clean shop cloth beneath the brake master cylinder to catch brake fluid spills.
3. Clean the outside of the reservoir on and around the reservoir cap prior to removing the cap and diaphragm.
4. Fill the brake master cylinder reservoir to the maximum-full level with GM approved brake fluid from a clean, sealed brake fluid container. Add brake fluid as needed to ensure that the brake master cylinder reservoir remains at least half-full throughout the bleed procedure. The reservoir cap must be installed at all times except when filling the reservoir. Refer to «Fluid and Lubricant Recommendations»(/buick/enclave/i-2007-2013/remont/lubrication-system/#maintenance-and-lubrication__fluid-and-lubricant-recommendations) .
5. Install a proper box-end wrench onto the wheel hydraulic circuit bleeder valve which has been serviced.
6. Install a transparent hose over the end of the bleeder valve.
7. Submerge the open end of the transparent hose into a transparent container partially filled with brake fluid from a clean, sealed brake fluid container.
8. Have an assistant slowly press the brake pedal fully and maintain steady pressure on the pedal.
9. Loosen the bleeder valve to purge air from the wheel hydraulic circuit.
10. Tighten the bleeder valve, then have the assistant slowly release the brake pedal.
11. Wait 15 seconds, then repeat steps 8-10 until all air is purged from the wheel hydraulic circuit.
12. After all air has been purged from the hydraulic circuit, tighten the bleeder valve and install the dust cap.
13. Fill the brake master cylinder reservoir to the maximum-fill level with GM approved brake fluid from a clean, sealed brake fluid container.
14. Slowly press and release the brake pedal. Observe the brake pedal feel.
15. If the brake pedal feels spongy, perform the Bleeding the Complete Brake Hydraulic System procedure
16. Turn the ignition key ON, with the engine OFF. Check to see if the brake system warning lamp remains illuminated.
17. If the brake system warning lamp remains illuminated, refer to «Diagnostic Starting Point - Vehicle»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-starting-point-vehicle) .

Bleeding the Complete Brake Hydraulic System

1. 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.
2. Place a clean shop cloth beneath the brake master cylinder to catch brake fluid spills.
3. Clean the outside of the reservoir on and around the reservoir cap prior to removing the cap and diaphragm.
4. Fill the brake master cylinder reservoir to the maximum-full level with GM approved brake fluid from a clean, sealed brake fluid container. Add brake fluid as needed to ensure that the brake master cylinder reservoir remains at least half-full throughout the bleed procedure. The reservoir cap must be installed at all times except when filling the reservoir. Refer to «Fluid and Lubricant Recommendations»(/buick/enclave/i-2007-2013/remont/lubrication-system/#maintenance-and-lubrication__fluid-and-lubricant-recommendations) .
5. If the master cylinder was replaced, the master cylinder must be bench bled. Refer to «Master Cylinder Bench Bleeding»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system__master-cylinder-bench-bleeding) .
6. If the brake pipes have been removed from the master cylinder, the following steps must be performed. With the rear brake pipe installed securely to the master cylinder, loosen and separate the front brake pipe fitting from the front port of the brake master cylinder. Allow a small amount of brake fluid to gravity bleed from the open port of the master cylinder. Capture and properly dispose of the brake fluid in an approved container. Install the front brake pipe fitting to the front port of the brake master cylinder and tighten the fitting. Refer to «Fastener Tightening Specifications»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system__fastener-tightening-specifications) . Have an assistant slowly press the brake pedal fully and maintain steady pressure on the pedal. Loosen the front brake pipe fitting from the front port of the brake master cylinder to purge air from the master cylinder port. Tighten the front brake pipe fitting, then have the assistant slowly release the brake pedal. Wait 15 seconds, then repeat steps 6.4-6.6 until all air is purged from the front brake pipe fitting of the front port of the master cylinder. After all air is purged from the front port of the brake master cylinder, tighten the front master cylinder brake pipe fitting. Refer to «Fastener Tightening Specifications»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system__fastener-tightening-specifications) . With the front brake pipe fitting installed securely to the front port of the brake master cylinder, loosen and separate the rear brake pipe fitting from the rear port of the brake master cylinder. Repeat steps 6.2-6.7 for the rear port of the brake master cylinder. After all air is purged from the rear port of the brake master cylinder, tighten the rear master cylinder brake pipe fitting. Refer to «Fastener Tightening Specifications»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system__fastener-tightening-specifications) . Slowly press and release the brake pedal. Observe the brake pedal feel. If the brake pedal feels spongy, proceed to step 7. If the brake pedal feels firm, proceed to step 24.
7. If the brake pipes have been removed from the brake pressure modulator valve (BPMV) assembly, if equipped, or the brake proportion valve assembly, if equipped, air must be purged from each port of the respective assembly beginning with the feed pipes from the master cylinder. Loosen and separate one of the master cylinder brake pipe fittings from the inlet port of the assembly to be bled. Allow a small amount of brake fluid to gravity bleed from the open port of the assembly. Capture and properly dispose of the brake fluid in an approved container. Install the brake pipe fitting and to the inlet port of the assembly and tighten securely. Have an assistant slowly press the brake pedal fully and maintain steady pressure on the pedal. Loosen the same brake pipe fitting to purge air from the open port of the assembly. Tighten the brake pipe fitting, then have the assistant slowly release the brake pedal. Wait 15 seconds, then repeat steps 7.4-7.6 until all air is purged from the brake pipe fitting of the assembly. Repeat steps 7.1-7.7 for all of the remaining ports of the assembly. After bleeding each port of the assembly, tighten all of the brake pipe fittings on the assembly. Refer to «Fastener Tightening Specifications»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system__fastener-tightening-specifications) . Fill the master cylinder reservoir to the maximum-full level with GM approved brake fluid from a clean, sealed brake fluid container. Slowly press and release the brake pedal. Observe the brake pedal feel. If the brake pedal feels spongy, proceed to step 8. If the brake pedal feels firm, proceed to step 24.
8. Install a proper box-end wrench onto the RIGHT REAR wheel hydraulic circuit bleeder valve.
9. Install a transparent hose over the end of the bleeder valve.
10. 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.
11. Have an assistant slowly press the brake pedal fully and maintain steady pressure on the brake pedal.
12. Loosen the bleeder valve to purge air from the wheel hydraulic circuit.
13. Tighten the bleeder valve, then have the assistant slowly release the brake pedal.
14. Wait 15 seconds, then repeat steps 11-13 until all air is purged from the wheel hydraulic circuit.
15. Tighten the RIGHT REAR hydraulic wheel circuit bleeder valve securely.
16. Install a proper box-end wrench onto the LEFT REAR wheel hydraulic circuit bleeder valve, then repeat steps 9-14..
17. Install a proper box-end wrench onto the RIGHT FRONT wheel hydraulic circuit bleeder valve, then repeat steps 9-14..
18. Install a proper box-end wrench onto the LEFT FRONT wheel hydraulic circuit bleeder valve, then repeat steps 9-14..
19. After completing the final wheel hydraulic circuit bleeding procedure, tighten all of the wheel hydraulic circuit bleeder valves and install the bleeder valve dust caps.
20. Fill the master cylinder reservoir to the maximum-full level with GM approved brake fluid from a clean, sealed brake fluid container.
21. Slowly press and release the brake pedal. Observe the brake pedal feel.
22. If the brake pedal feels spongy, perform the following procedure. If equipped with antilock brakes, install a scan tool and perform the «Antilock Brake System Automated Bleed»(/buick/enclave/i-2007-2013/remont/anti-locktraction-control/#antilock-brake-system) to remove air which may be trapped in the BPMV. Inspect the hydraulic brake system for external leaks. Refer to «Brake System External Leak Inspection»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system__brake-system-external-leak-inspection) . Repeat the Bleeding the Complete Brake Hydraulic System procedure.
23. If the brake pedal still feels spongy, pressure bleed the hydraulic brake system. Refer to «Hydraulic Brake System Bleeding (Manual)»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system) , «Hydraulic Brake System Bleeding (Pressure)»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system)
24. Turn the ignition switch ON with the engine OFF. Check to see if the brake system warning lamp remains illuminated.
25. If the brake system warning lamp remains illuminated, refer to «Diagnostic Starting Point - Vehicle»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-starting-point-vehicle) .

If hydraulic components were serviced on only one wheel hydraulic circuit, perform the following procedure.

Bleeding a Single Hydraulic Brake Circuit

1. 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.
2. Place a clean shop cloth beneath the brake master cylinder to catch brake fluid spills.
3. Clean the outside of the reservoir on and around the reservoir cap prior to removing the cap and diaphragm.
4. Fill the brake master cylinder reservoir to the maximum-full level with GM approved brake fluid from a clean, sealed brake fluid container. Refer to «Fluid and Lubricant Recommendations»(/buick/enclave/i-2007-2013/remont/lubrication-system/#maintenance-and-lubrication__fluid-and-lubricant-recommendations) .
5. Following the brake pressure bleeder manufacturers instructions, fill the brake pressure bleeder with GM approved brake fluid from a clean, sealed brake fluid container.
6. Install the appropriate master cylinder reservoir adapter and connect the brake pressure bleeder.
7. Charge the brake pressure bleeder air tank to 170-200 kPa/1.7-2.0 bar (25-30 psi), or as recommended by the brake pressure bleeder manufacturers instructions.
8. Open the brake pressure bleeder fluid tank valve to allow pressurized brake fluid to enter the brake hydraulic system.
9. Wait approximately 30 seconds, then inspect the entire hydraulic brake system for external brake fluid leaks.
10. Wait approximately 30 seconds, then inspect the entire hydraulic brake system in order to ensure that there are no existing external brake fluid leaks.
11. Install a proper box-end wrench onto the wheel hydraulic circuit bleeder valve which has been serviced.
12. Install a transparent hose over the end of the bleeder valve.
13. Submerge the open end of the transparent hose into a transparent container partially filled with brake fluid from a clean, sealed brake fluid container.
14. Loosen the bleeder valve to purge air from the wheel hydraulic circuit.
15. Allow fluid to flow until air bubbles stop flowing from the bleeder.
16. After all air has been purged from the hydraulic circuit, tighten the bleeder valve and install the dust cap.
17. Close the brake pressure bleeder fluid tank valve then disconnect the brake pressure bleeder from the master cylinder reservoir bleeder adapter.
18. Remove the master cylinder reservoir bleeder adapter from the master cylinder reservoir.
19. Fill the brake master cylinder reservoir to the maximum-fill level with GM approved brake fluid from a clean, sealed brake fluid container.
20. Slowly press and release the brake pedal. Observe the brake pedal feel.
21. If the brake pedal feels spongy, perform the Bleeding the Complete Brake Hydraulic System procedure
22. Turn the ignition key ON, with the engine OFF. Check to see if the brake system warning lamp remains illuminated.
23. If the brake system warning lamp remains illuminated, refer to «Diagnostic Starting Point - Vehicle»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-starting-point-vehicle) .

Bleeding the Complete Brake Hydraulic System

1. 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.
2. Place a clean shop cloth beneath the brake master cylinder to catch brake fluid spills.
3. Clean the outside of the reservoir on and around the reservoir cap prior to removing the cap and diaphragm.
4. Fill the brake master cylinder reservoir to the maximum-full level with GM approved brake fluid from a clean, sealed brake fluid container. Refer to «Fluid and Lubricant Recommendations»(/buick/enclave/i-2007-2013/remont/lubrication-system/#maintenance-and-lubrication__fluid-and-lubricant-recommendations) .
5. If the master cylinder was replaced, the master cylinder must be bench bled. Refer to «Master Cylinder Bench Bleeding»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system__master-cylinder-bench-bleeding) .
6. If the brake pipes have been removed from the master cylinder, the following steps must be performed. With the rear brake pipe installed securely to the master cylinder, loosen and separate the front brake pipe fitting from the front port of the brake master cylinder. Allow a small amount of brake fluid to gravity bleed from the open port of the master cylinder. Capture and properly dispose of the brake fluid in an approved container. Install the front brake pipe fitting to the front port of the brake master cylinder and tighten the fitting. Have an assistant slowly press the brake pedal fully and maintain steady pressure on the pedal. Loosen the front brake pipe fitting from the front port of the brake master cylinder to purge air from the master cylinder port. Tighten the front brake pipe fitting, then have the assistant slowly release the brake pedal. Wait 15 seconds, then repeat steps 6.4-6.6 until all air is purged from the front brake pipe fitting of the front port of the master cylinder. After all air is purged from the front port of the brake master cylinder, tighten the front master cylinder brake pipe fitting. Refer to «Fastener Tightening Specifications»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system__fastener-tightening-specifications) . With the front brake pipe fitting installed securely to the front port of the brake master cylinder, loosen and separate the rear brake pipe fitting from the rear port of the brake master cylinder. Repeat steps 6.2-6.7 for the rear port of the brake master cylinder. After all air is purged from the rear port of the brake master cylinder, tighten the rear master cylinder brake pipe fitting. Refer to «Fastener Tightening Specifications»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system__fastener-tightening-specifications) . Slowly press and release the brake pedal. Observe the brake pedal feel. If the brake pedal feels spongy, proceed to step 7. If the brake pedal feels firm, proceed to step 24.
7. If the brake pipes have been removed from the brake pressure modulator valve (BPMV) assembly, if equipped, or the brake proportion valve assembly, if equipped, air must be purged from each port of the respective assembly beginning with the feed pipes from the master cylinder. Loosen and separate one of the master cylinder brake pipe fittings from the inlet port of the assembly to be bled. Allow a small amount of brake fluid to gravity bleed from the open port of the assembly. Capture and properly dispose of the brake fluid in an approved container. Install the brake pipe fitting and to the inlet port of the assembly and tighten securely. Have an assistant slowly press the brake pedal fully and maintain steady pressure on the pedal. Loosen the same brake pipe fitting to purge air from the open port of the assembly. Tighten the brake pipe fitting, then have the assistant slowly release the brake pedal. Wait 15 seconds, then repeat steps 7.4-7.6 until all air is purged from the brake pipe fitting of the assembly. Repeat steps 7.1-7.7 for all of the remaining ports of the assembly. After bleeding each port of the assembly, tighten all of the brake pipe fittings on the assembly. Refer to «Fastener Tightening Specifications»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system__fastener-tightening-specifications) . Fill the master cylinder reservoir to the maximum-full level with GM approved brake fluid from a clean, sealed brake fluid container. Slowly press and release the brake pedal. Observe the brake pedal feel. If the brake pedal feels spongy, proceed to step 8. If the brake pedal feels firm, proceed to step 24.
8. Following the brake pressure bleeder manufacturers instructions, fill the brake pressure bleeder with GM approved brake fluid from a clean, sealed brake fluid container.
9. Install the appropriate master cylinder reservoir adapter and connect the brake pressure bleeder.
10. Charge the brake pressure bleeder air tank to 170-200 kPa/1.7-2.0 bar (25-30 psi), or as recommended by the brake pressure bleeder manufacturers instructions.
11. Open the brake pressure bleeder fluid tank valve to allow pressurized brake fluid to enter the brake hydraulic system.
12. Wait approximately 30 seconds, then inspect the entire hydraulic brake system for external brake fluid leaks.
13. Install a proper box-end wrench onto the RIGHT REAR wheel hydraulic circuit bleeder valve.
14. Install a transparent hose over the end of the bleeder valve.
15. 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.
16. Have an assistant slowly press the brake pedal fully and maintain steady pressure on the brake pedal.
17. Loosen the bleeder valve to purge air from the wheel hydraulic circuit.
18. Tighten the bleeder valve, then have the assistant slowly release the brake pedal.
19. Wait 15 seconds, then repeat steps 11-13 until all air is purged from the wheel hydraulic circuit.
20. Tighten the RIGHT REAR hydraulic wheel circuit bleeder valve securely.
21. Install a proper box-end wrench onto the LEFT REAR wheel hydraulic circuit bleeder valve, then repeat steps 9-14..
22. Install a proper box-end wrench onto the RIGHT FRONT wheel hydraulic circuit bleeder valve, then repeat steps 9-14..
23. Install a proper box-end wrench onto the LEFT FRONT wheel hydraulic circuit bleeder valve, then repeat steps 9-14..
24. After completing the final wheel hydraulic circuit bleeding procedure, tighten all of the wheel hydraulic circuit bleeder valves and install the bleeder valve dust caps.
25. Close the brake pressure bleeder fluid tank valve.
26. Remove the brake pressure bleeding equipment from the vehicle.
27. Fill the brake master cylinder reservoir to the maximum-full level with GM approved brake fluid from a clean, sealed brake fluid container. Refer to «Fluid and Lubricant Recommendations»(/buick/enclave/i-2007-2013/remont/lubrication-system/#maintenance-and-lubrication__fluid-and-lubricant-recommendations) .
28. Slowly press and release the brake pedal. Observe the brake pedal feel.
29. If the brake pedal feels spongy, perform the following procedure. If equipped with antilock brakes, install a scan tool and perform the «Antilock Brake System Automated Bleed»(/buick/enclave/i-2007-2013/remont/anti-locktraction-control/#antilock-brake-system) to remove air which may be trapped in the BPMV. Inspect the hydraulic brake system for external leaks. Refer to «Brake System External Leak Inspection»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system__brake-system-external-leak-inspection) . Repeat the Bleeding the Complete Brake Hydraulic System procedure.
30. If the brake pedal still feels spongy, pressure bleed the hydraulic brake system. Refer to «Hydraulic Brake System Bleeding (Manual)»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system) , «Hydraulic Brake System Bleeding (Pressure)»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system)
31. Turn the ignition switch ON with the engine OFF. Check to see if the brake system warning lamp remains illuminated.
32. If the brake system warning lamp remains illuminated, refer to «Diagnostic Starting Point - Vehicle»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-starting-point-vehicle) .

1. Inspect the brake fluid for the following conditions, indicating brake fluid contamination: Fluid separation, indicating 2 types of fluid are present; a substance other than the recommended brake fluid has been introduced into the brake hydraulic system Swirled appearance - oil-based substance Layered appearance - silicone-based substance Fluid discoloration, indicating the presence of moisture or particles that have been introduced into the brake hydraulic system Cloudy appearance - moisture Dark appearance/suspended particles in fluid - dirt, rust, corrosion, brake dust
2. Inspect the master cylinder reservoir cap diaphragm and the reservoir-to-master cylinder grommets for swelling, indicating brake fluid contamination.
3. If the brake fluid WAS contaminated with an oil-based or a silicone-based substance, indicated by fluid separation and/or a swollen master cylinder reservoir cap diaphragm and/or swollen reservoir-to-master cylinder grommets, perform the following: Remove ALL of the following components listed from the vehicle. Each component contains internal rubber seals/linings which have been contaminated by the contaminated brake fluid in the brake hydraulic system. Refer to the procedures indicated: «Master Cylinder Reservoir Replacement»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system) «Master Cylinder Replacement»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system) «Front Brake Hose Replacement»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system) «Rear Brake Hose Replacement»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system) «Front Brake Caliper Replacement»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#disc-brake-system) «Rear Brake Caliper Replacement»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#disc-brake-system) «Brake Pressure Modulator Valve Replacement»(/buick/enclave/i-2007-2013/remont/anti-locktraction-control/#antilock-brake-system) Clean out all the hydraulic brake pipes using denatured alcohol, or equivalent. Dry the brake pipes using non-lubricated, filtered air. Repair or replace ALL of the following components listed and install them to the vehicle. Each component contains internal rubber seals/linings which have been contaminated by the contaminated brake fluid in the brake hydraulic system. Refer to the procedures indicated: «Master Cylinder Replacement»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system) ; also perform the following: Clean the brake master cylinder reservoir using denatured alcohol, or equivalent, then dry the reservoir using non-lubricated, filtered air. Inspect the reservoir for cracks and/or damage and replace if necessary. Refer to «Master Cylinder Reservoir Replacement»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system) . Replace the brake master cylinder reservoir cap diaphragm. «Front Brake Hose Replacement»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system) «Rear Brake Hose Replacement»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system) «Front Brake Caliper Replacement»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#disc-brake-system) «Rear Brake Caliper Replacement»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#disc-brake-system) «Brake Pressure Modulator Valve Replacement»(/buick/enclave/i-2007-2013/remont/anti-locktraction-control/#antilock-brake-system)
4. If the brake fluid was NOT contaminated with an oil-based or a silicone-based substance, but WAS contaminated with water or dirt, rust, corrosion, and/or brake dust, replace the brake master cylinder reservoir cap diaphragm. The diaphragm may have allowed the moisture or particles to enter the hydraulic system.
5. Fill the brake master cylinder reservoir to the maximum-fill level with approved brake fluid from a clean, sealed brake fluid container as specified in the owners manual.
6. Pressure bleed the hydraulic brake system. Begin the procedure with the pressure bleeder reservoir filled to the maximum-fill level with the correct brake fluid as indicated. Refer to «Hydraulic Brake System Bleeding (Manual)»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system) , «Hydraulic Brake System Bleeding (Pressure)»(/buick/enclave/i-2007-2013/remont/mechanical-hydraulic/#hydraulic-brake-system) .

1. Place the vehicle on a level surface and apply the park brake.
2. With the engine OFF, apply and release the brake pedal several times until the brake pedal becomes firm to deplete the vacuum reserve in the vacuum brake booster.
3. Remove the air cleaner housing cover and duct. Refer to «Air Cleaner Element Replacement»(/buick/enclave/i-2007-2013/remont/testing-diagnostics/#engine-controlsfuel-36l-repair-instructions) .
4. Disconnect the brake fluid level indicator switch electrical connector.
5. Remove the power brake booster vacuum check valve and hose assembly (1) from the brake booster and position aside.
6. Disconnect the power brake booster vacuum sensor electrical connector.
7. Remove the power brake booster vacuum sensor (1).
8. Release the front and rear brake pipes (1) from the routing clip on the frame rail.
9. Remove the 2 nuts (2) from the brake pressure modulator valve (BPMV) assembly.
10. Carefully lift the BPMV assembly over the studs and position forward slightly.
11. Remove the master cylinder nuts (1).
12. Without disconnecting the brake pipes from the master cylinder, remove the master cylinder assembly and position aside.
13. Place the brake master cylinder in an upright position and support with heavy mechanics wire or equivalent.
14. Remove the left side instrument panel insulator panel. Refer to «Instrument Panel Insulator Panel Replacement - Left Side (Enclave)»(/buick/enclave/i-2007-2013/remont/exteriorinterior-trim/#instrument-panel-trim-and-console-trim) , «Instrument Panel Insulator Panel Replacement - Left Side (Acadia)»(/buick/enclave/i-2007-2013/remont/exteriorinterior-trim/#instrument-panel-trim-and-console-trim) , «Instrument Panel Insulator Panel Replacement - Left Side (Traverse)»(/buick/enclave/i-2007-2013/remont/exteriorinterior-trim/#instrument-panel-trim-and-console-trim) .
15. Remove the driver knee bolster. Refer to «Driver Knee Bolster Replacement (Acadia)»(/buick/enclave/i-2007-2013/remont/exteriorinterior-trim/#instrument-panel-trim-and-console-trim) , «Driver Knee Bolster Replacement (Traverse)»(/buick/enclave/i-2007-2013/remont/exteriorinterior-trim/#instrument-panel-trim-and-console-trim) , «Driver Knee Bolster Replacement (Enclave)»(/buick/enclave/i-2007-2013/remont/exteriorinterior-trim/#instrument-panel-trim-and-console-trim) .
16. Remove the brake pedal pushrod retaining clip (1).
17. Remove the brake pedal pushrod clevis pin (2) and disconnect the pushrod from the brake pedal.
18. Remove the intermediate steering shaft. Refer to «Intermediate Steering Shaft Replacement»(/buick/enclave/i-2007-2013/remont/steering-column-switches/#steering-wheel-and-steering-column) .
19. Remove the 4 vacuum brake booster nuts.
20. Pull the vacuum brake booster forward and tilt upward slightly until the mounting studs clear the dash panel.
21. Remove the vacuum brake booster.

1. Align the vacuum brake booster mounting studs to the dash panel.
2. Install the vacuum brake booster.
3. Install the 4 vacuum brake booster nuts and tighten to 25 (18 lb ft).
4. Install the intermediate steering shaft. Refer to «Intermediate Steering Shaft Replacement»(/buick/enclave/i-2007-2013/remont/steering-column-switches/#steering-wheel-and-steering-column) .
5. Connect the brake pedal pushrod to the brake pedal and install the clevis pin (2).
6. Install the brake pedal pushrod retaining clip (1).
7. Install the driver knee bolster. Refer to «Driver Knee Bolster Replacement (Acadia)»(/buick/enclave/i-2007-2013/remont/exteriorinterior-trim/#instrument-panel-trim-and-console-trim) , «Driver Knee Bolster Replacement (Traverse)»(/buick/enclave/i-2007-2013/remont/exteriorinterior-trim/#instrument-panel-trim-and-console-trim) , «Driver Knee Bolster Replacement (Enclave)»(/buick/enclave/i-2007-2013/remont/exteriorinterior-trim/#instrument-panel-trim-and-console-trim) .
8. Install the left side instrument panel insulator panel. Refer to «Instrument Panel Insulator Panel Replacement - Left Side (Enclave)»(/buick/enclave/i-2007-2013/remont/exteriorinterior-trim/#instrument-panel-trim-and-console-trim) , «Instrument Panel Insulator Panel Replacement - Left Side (Acadia)»(/buick/enclave/i-2007-2013/remont/exteriorinterior-trim/#instrument-panel-trim-and-console-trim) , «Instrument Panel Insulator Panel Replacement - Left Side (Traverse)»(/buick/enclave/i-2007-2013/remont/exteriorinterior-trim/#instrument-panel-trim-and-console-trim) .
9. Inspect the master cylinder to vacuum brake booster seal for damage and replace, if necessary.
10. Position the master cylinder to the vacuum booster.
11. Install the master cylinder nuts (1) and tighten to 20 (15 lb ft).
12. Position the BPMV assembly over the studs.
13. Install the 2 nuts (2) to the BPMV and bracket assembly and tighten to 20 (15 lb ft).
14. Install the front and rear brake pipes (1) to the routing clip on the frame rail.
15. Install the power brake booster vacuum sensor (1).
16. Connect the power brake booster vacuum sensor electrical connector.
17. Install the power brake booster vacuum check valve and hose assembly (1) to the brake booster.
18. Connect the brake fluid level indicator switch electrical connector.
19. Install the air cleaner housing cover and duct. Refer to «Air Cleaner Element Replacement»(/buick/enclave/i-2007-2013/remont/testing-diagnostics/#engine-controlsfuel-36l-repair-instructions) .

1. Turn the ignition switch to the OFF position.
2. Apply and release the brake pedal several times until the brake pedal becomes firm to deplete the brake booster vacuum reserve.
3. Remove the power brake booster vacuum check valve (1) from the power vacuum brake booster.
4. Remove the fuel injector sight shield. Refer to «Fuel Injector Sight Shield Replacement»(/buick/enclave/i-2007-2013/remont/mechanical/#engine-mechanical-36l-repair-instructions-on-vehicle) .
5. Release the vacuum hose routing clip (1) from the intake manifold ball stud.
6. Disconnect the power vacuum brake booster hose (1) from the intake manifold vacuum port.
7. Release the quick connect (2) from the power brake booster auxiliary pump.
8. Disconnect the power brake booster check valve and hose assembly (1) from the brake booster.
9. Remove the vacuum brake booster hose assembly from the vehicle.

1. Install the power brake booster check valve and hose assembly (1) to the brake booster.
2. Connect the power vacuum brake booster hose (1) to the intake manifold vacuum port.
3. Connect the quick connect (2) to the power brake booster auxiliary pump.
4. Connect the vacuum hose routing clip (1) to the intake manifold ball stud.
5. Install the power brake booster vacuum check valve (1) to the power vacuum brake booster.
6. Install the fuel injector sight shield. Refer to «Fuel Injector Sight Shield Replacement»(/buick/enclave/i-2007-2013/remont/mechanical/#engine-mechanical-36l-repair-instructions-on-vehicle) .

1. Turn the ignition switch to the OFF position.
2. Apply and release the brake pedal several times until the brake pedal becomes firm to deplete the brake booster vacuum reserve.
3. Disconnect the power brake booster vacuum sensor electrical connector.
4. Remove the power brake booster vacuum sensor (1) from the brake booster.

1. Install the power brake booster vacuum sensor (1) to the brake booster.
2. Connect the power brake booster vacuum sensor electrical connector.

1. Turn the ignition switch to the OFF position.
2. Apply and release the brake pedal several times until the brake pedal becomes firm to deplete the brake booster vacuum reserve.
3. Remove the fuel injector sight shield. Refer to «Fuel Injector Sight Shield Replacement»(/buick/enclave/i-2007-2013/remont/mechanical/#engine-mechanical-36l-repair-instructions-on-vehicle) .
4. Release the quick connect (2) from the power brake booster auxiliary pump.
5. Position the vacuum brake booster hose assembly aside.
6. Disconnect the power brake booster auxiliary pump electrical connector.
7. Release the power brake booster auxiliary pump electrical connector (1) from the bracket.
8. Remove the power brake booster auxiliary pump nuts (1).
9. Remove the power brake booster auxiliary pump bolts and the pump.
10. If necessary, remove the power brake booster auxiliary pump insulators (1) and sleeves (2).
11. If necessary, remove the power brake booster auxiliary pump bracket bolts (1) and bracket (2).

1. If removed, install the power brake booster auxiliary pump bracket bolts (1) and bracket (2) and tighten the bolts to 10 N.m (89 lb in).
2. If removed, install the power brake booster auxiliary pump insulators (1) and sleeves (2).
3. Install the power brake booster auxiliary pump bolts and the pump to the bracket.
4. Install the power brake booster auxiliary pump nuts (1) and tighten the nuts to 10 N.m (89 lb in).
5. Install the power brake booster auxiliary pump electrical connector (1) to the bracket.
6. Connect the power brake booster auxiliary pump electrical connector.
7. Connect the quick connect (2) to the power brake booster auxiliary pump.
8. Install the fuel injector sight shield. Refer to «Fuel Injector Sight Shield Replacement»(/buick/enclave/i-2007-2013/remont/mechanical/#engine-mechanical-36l-repair-instructions-on-vehicle) .

System Component Description

The brake assist system consists of the following

System Operation

Brake system input force from the driver is multiplied by the brake pedal and transferred by the pedal pushrod to the hydraulic brake master cylinder. Effort required to apply the brake system is reduced by the operation of the vacuum brake booster.

When brake system force is applied, vacuum to the rear of the diaphragm(s) is cut off, and air at atmospheric pressure is admitted in its place. The vacuum acts to pull the diaphragm(s) forward, while the atmospheric pressure acts to push from behind. As a result, the amount of effort required by the driver is reduced. When input force is removed, vacuum again replaces atmospheric pressure within the vacuum power brake booster to help return the booster to rest. Return springs maintain the system in a rest position.

If the vehicle is equipped with a vacuum monitoring system, the powertrain control module(s) typically will alter powertrain functions and/or command the vacuum pump ON, if equipped, to provide for the vacuum needs of the brake assist system, as operating conditions warrant.

The brake booster vacuum assist system consists of the following

The engine control module (ECM) actuates the brake booster vacuum pump to generate additional vacuum to the vacuum brake booster if low vacuum is detected by the ECM.

Brake Warning Indicator

The instrument panel cluster (IPC) illuminates the Red Brake Warning indicator when one or more of the following occurs.

1. The body control module (BCM) detects that the park brake is engaged.
2. The IPC detects the low brake fluid level switch is closed.
3. The electronic brake control module (EBCM) detects an ABS malfunction which disables dynamic rear proportioning (DRP), and sends a serial data message to the IPC.
4. The IPC performs the bulb check at the start of each ignition cycle. The Red Brake Warning indicator illuminates momentarily.
5. The IPC detects a loss of serial data with the EBCM.

The hydraulic brake system consists of the following

Mechanical force is converted into hydraulic pressure by the master cylinder, regulated to meet braking system demands by the pressure balance control system, and delivered to the hydraulic brake wheel circuits by the pipes and flexible hoses. The wheel apply components then convert the hydraulic pressure back into mechanical force which presses linings against rotating brake system components.

Special Tools

Illustration Tool Number/ Description J 28662 Brake Pedal Effort Gauge J 29532 Diaphragm Pressure Bleeder J 44894-A Brake Pressure Bleeder Adapter J 45405 Brake Pipe Flaring Kit

Scheme 6

Scheme 7

Scheme 8

Scheme 9

See also:
• Diagnostic System Check - Vehicle
• Strategy Based Diagnosis
• Diagnostic Procedure Instructions
• COMPONENT CONNECTOR END VIEWS - INDEX
• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs
• Control Module References
• Diagnostic Repair Verification
• Relay Replacement (Within an Electrical Center)
• Relay Replacement (Attached to Wire Harness)
• Checking Aftermarket Accessories
• Parking Brake Indicator Switch Replacement
• Park Brake System Diagnosis
• Symptoms - Suspension General Diagnosis
• Brake Pad Inspection
• Front Disc Brake Pads Replacement
• Front Disc Brake Mounting and Hardware Inspection
• Rear Disc Brake Mounting and Hardware Inspection
• Front Wheel Drive Shaft Outer Joint and Boot Replacement
• Rear Wheel Drive Shaft Outer Joint and Boot Replacement
• Brake Rotor Thickness Measurement
• Brake Rotor Thickness Variation Measurement
• Brake Rotor Surface and Wear Inspection
• Brake Rotor Refinishing
• Brake Rotor Assembled Lateral Runout Measurement
• Brake Rotor Assembled Lateral Runout Correction
• Brake Pressure Modulator Valve Replacement
• Lifting and Jacking the Vehicle
• Tire and Wheel Removal and Installation
• Brake Fluid Irritant Warning
• Brake Fluid Effects on Paint and Electrical Components Caution
• Air Cleaner Element Replacement
• Fastener Caution
• Windshield Washer Solvent Heater Replacement (Traverse)
• Instrument Panel Insulator Panel Replacement - Left Side (Enclave)
• Intermediate Steering Shaft Replacement
• Brake Pedal Position Sensor Calibration
• Brake Dust Warning
• Fluid and Lubricant Recommendations
• Diagnostic Starting Point - Vehicle
• Fuel Injector Sight Shield Replacement
• ABS Description and Operation
• DTC C0267
• Brake Fluid Loss
• Brake Assist System Diagnosis
• Brake System Vacuum Source Test
• Hydraulic Brake Component Operation Visual Inspection
• Brake Pulsation
• Brake System Noise
• Brake Pedal Excessive Travel
• Brake Pedal Excessive Effort
• Brakes Drag
• Symptoms - Hydraulic Brakes
• Brake Pedal Travel Measurement and Inspection
• Brake Pedal Pushrod Inspection
• Brake Pipe Replacement
• Master Cylinder Reservoir Filling
• Brake Pipe and Hose Inspection
• Brake System Internal Leak Test
• Brake System External Leak Inspection
• Master Cylinder Bench Bleeding
• Fastener Tightening Specifications