Hydraulic Brake System Cadillac ATS I

Fastener Tightening Specifications

Fastener Tightening Specifications

Brake Component Specifications

Brake Component Specifications

Brake System Specifications

Brake System Specifications

Scheme 5

Diagnostic Code Index

DIAGNOSTIC CODE INDEX

Diagnostic Instructions

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/ats/i-2012-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/ats/i-2012-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/ats/i-2012-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

DTC Descriptor

For symptom byte information refer to Symptom Byte List .

Diagnostic Fault Information

Circuit/System Description

The brake fluid level switch monitors the level of the brake fluid in the brake fluid reservoir. When the electronic brake control module sees the brake fluid level switch input closed, the DTC is set.

Conditions for Running the DTC

Ignition ON.

Conditions for Setting the DTC

1. Low brake fluid level is detected for 5 s.
2. An open is detected on the ground circuit.
3. An open, short to ground, or short to voltage is detected on the signal circuit.

Action Taken When the DTC Sets

1. The electronic brake control module disables the traction control and stability control for the duration of the ignition cycle.
2. The traction control/stability control-active indicator turns ON.
3. The brake warning indicator turns ON.

Conditions for Clearing the DTC

The condition for setting the DTC is no longer present.

Reference Information

Schematic Reference

Hydraulic Brake Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Hydraulic Brake System Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/cadillac/ats/i-2012-2014/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/cadillac/ats/i-2012-2014/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/ats/i-2012-2014/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/cadillac/ats/i-2012-2014/remont/body-electrical/#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. Verify that the brake fluid level is above the minimum level. If low Refer to «Brake Fluid Loss»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system__brake-fluid-loss) . If above minimum level
2. Refer to Circuit/System Testing.

Circuit/System Testing

1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the B20 Brake Fluid Level Switch. It may take up to 2 minutes for all vehicle systems to power down.
2. Test for less than 10 ohms between the ground circuit terminal 2 and ground. If 10 ohms or greater Ignition OFF. Test for less than 2 ohms in the ground circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, repair the open/high resistance in the ground connection. If less than 10 ohms
3. Ignition ON.
4. Verify the scan tool Brake Fluid Level Sensor parameter is OK. If the parameter is not OK Ignition OFF, disconnect the harness connector at the K17 Electronic Brake Control Module. Test for infinite resistance between the signal circuit terminal 1 and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance, replace the K17 Electronic Brake Control Module. If the parameter is OK
5. Install a 3 A fused jumper wire between the signal circuit terminal 1 and ground.
6. Verify the scan tool Brake Fluid Level Sensor parameter is Low. If the parameter is not Low Ignition OFF, disconnect the harness connector at the K17 Electronic Brake Control Module, ignition ON. Test for less than 1 V between the signal circuit and ground. If 1 V or greater, repair the short to voltage on the circuit. If less than 1 V. Test for less than 2 ohms in the signal circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, replace the K17 Electronic Brake Control Module. If the parameter is Low
7. Test or replace the B20 Brake Fluid Level Switch.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

1. «Brake Fluid Level Indicator Switch Replacement»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system)
2. «Control Module References»(/cadillac/ats/i-2012-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for electronic brake control module replacement, programming and setup.

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/ats/i-2012-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/ats/i-2012-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/ats/i-2012-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

For symptom byte information refer to Symptom Byte List .

The brake booster vacuum sensor measures the vacuum in the brake booster assembly. The electronic brake control module supplies a 5 V reference and a low reference circuit to the brake booster vacuum sensor. The vacuum sensor supplies a voltage signal in relation to the pressure in the brake booster to the electronic brake control module. When the vacuum within the system becomes weak, the electronic brake control module turns ON the brake booster pump motor by providing ground to the brake booster pump motor relay. The relay activates and supplies battery voltage to the brake booster pump motor.

Ignition ON.

A short to ground or open/high resistance is detected on the control circuit.

The DTC is stored in memory.

The condition for setting the DTC is no longer present.

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»(/cadillac/ats/i-2012-2014/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/cadillac/ats/i-2012-2014/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/ats/i-2012-2014/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/cadillac/ats/i-2012-2014/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

1. Ignition ON.
2. Verify the M9 Brake Booster Pump Motor turns ON and OFF when commanding the Brake Booster Electric Vacuum Pump On and Off with a scan tool. If the M9 Brake Booster Pump Motor does not turn ON and OFF Refer to Circuit/System Testing. If the M9 Brake Booster Pump Motor turn ON and OFF
3. All OK.

1. Ignition OFF, disconnect the KR14 Brake Booster Pump Motor Relay, ignition ON.
2. Verify a test lamp illuminates between the B+ circuit terminal 30 and ground. If the test lamp does not illuminate and the circuit fuse is good Ignition OFF, remove the test lamp. Test for less than 2 ohms in the B+ circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, verify the fuse is not open and there is voltage at the fuse. If the test lamp does not illuminate and the circuit fuse is open Ignition OFF, remove the test lamp. Test for infinite resistance between the B+ circuit and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance, Disconnect the M9 Brake Booster Pump Motor. Test for greater than 10 ohms between the control circuit terminal 87 and ground. If less than 10 ohms, repair the short to ground on the circuit. If greater than 10 ohms, test or replace the M9 Brake Booster Pump Motor. If the test lamp illuminates
3. Ignition OFF and all vehicle systems OFF. It may take up to 2 min for all vehicle systems to power down.
4. Test for less than 10 ohms between the ground circuit terminal 86 and ground. If 10 ohms or greater Ignition OFF. Test for less than 2 ohms in the ground circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, repair the open/high resistance in the ground connection. If less than 10 ohms
5. Connect a test lamp between the control circuit terminal 85 and the ground circuit terminal 86.
6. Verify the test lamp turns ON and OFF when commanding the Brake Booster Pump Motor On and Off with a scan tool. If the test lamp is always OFF Ignition OFF, remove the test lamp, disconnect the harness connector at the K17 Electronic Brake Control Module, ignition ON. Test for infinite resistance between the control circuit and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance Test for less than 2 ohms in the control circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, replace the K17 Electronic Brake Control Module. If the test lamp is always ON Ignition OFF, remove the test lamp, disconnect the harness connector at the K17 Electronic Brake Control Module. Test for less than 1 V between the control circuit and ground. If 1 V or greater, repair the short to voltage on the circuit. If less than 1 V, replace the K17 Electronic Brake Control Module. If the test lamp turns ON and OFF
7. Verify a test lamp does not illuminate between the control circuit terminal 87 and ground. If the test lamp illuminates Repair the short to voltage on the circuit. If the test lamp does not illuminate
8. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the M9 Brake Booster Pump Motor. It may take up to 2 minutes for all vehicle systems to power down.
9. Test for less than 10 ohms between the M9 Brake Booster Pump Motor ground circuit terminal 2 and ground. If 10 ohms or greater Ignition OFF. Test for less than 2 ohms in the ground circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, repair the open/high resistance in the ground connection. If less than 10 ohms
10. Connect the harness connector at the M9 Brake Booster Pump Motor.
11. Ignition ON, connect a 30 A fused jumper wire between the B+ circuit terminal 30 and the control circuit terminal 87.
12. Verify the M9 Brake Booster Pump Motor is activated. If the M9 Brake Booster Pump Motor does not activate Ignition OFF, remove the jumper wire. Test for less than 2 ohms in the control circuit terminal 87 end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, test or replace the M9 Brake Booster Pump Motor. If the M9 Brake Booster Pump Motor activates
13. Test or replace the KR14 Brake Booster Pump Motor Relay.

Component Testing

Relay Test

1. Ignition OFF, remove the KR14 Brake Booster Pump Motor Relay.
2. Test for 70-150 ohms between terminals 85 and 86. If less than 70 ohms or greater than 150 ohms Replace the KR14 Brake Booster Pump Motor Relay. If between 70-150 ohms
3. Test for infinite resistance between the terminals listed below: 30 and 86 30 and 87 30 and 85 85 and 87 If less than infinite resistance Replace the KR14 Brake Booster Pump Motor Relay. If infinite resistance
4. Install a 30 A fused jumper wire between relay terminal 85 and 12 V. Install a jumper wire between relay terminal 86 and ground.
5. Test for less than 10 ohms between terminals 30 and 87. If 10 ohms or greater Replace the KR14 Brake Booster Pump Motor Relay. If less than 10 ohms
6. All OK.

Perform the Diagnostic Repair Verification after completing the repair.

1. «Power Brake Booster Pump Replacement (3.6L)»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system) , «Power Brake Booster Pump Replacement (2.0L, 2.5L)»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system)
2. «Control Module References»(/cadillac/ats/i-2012-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for electronic brake control module replacement, programming and setup

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/ats/i-2012-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/ats/i-2012-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/ats/i-2012-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

For symptom byte information refer to Symptom Byte List .

The brake booster vacuum sensor measures the vacuum in the brake booster assembly. The electronic brake control module supplies a 5 V reference and a low reference circuit to the brake booster vacuum sensor. The vacuum sensor supplies a voltage signal in relation to the pressure in the brake booster to the electronic brake control module.

Engine running.

The electronic brake control module detected a weak vacuum in the brake booster assembly for 120 s.

The DTC is stored in memory.

1. A current DTC clears when the diagnostic runs and passes.
2. The electronic brake control module will turn OFF the indicator in the next ignition cycle.

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»(/cadillac/ats/i-2012-2014/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/cadillac/ats/i-2012-2014/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/ats/i-2012-2014/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/cadillac/ats/i-2012-2014/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References Control Module References for scan tool information

1. Ignition ON.
2. Verify that DTC C1100 is not set. If the DTC is set Refer to «DTC C1100»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system) . If the DTC is not set
3. Verify that the brake booster vacuum system has no damage, leakage or incorrect installation. If damage, leakage or incorrect installation is found Refer to «Brake Assist System Diagnosis»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system__brake-assist-system-diagnosis) . If the inspection is OK
4. Test or replace the B19B Brake Booster Vacuum Sensor.
5. Verify the DTC does not set while operating the vehicle under the Conditions for Running the DTC. If the DTC sets Replace the K17 Electronic Brake Control Module. If the DTC does not set
6. All OK.

Perform the Diagnostic Repair Verification after completing the repair.

Control Module References for electronic brake control module replacement, programming and setup

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/ats/i-2012-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/ats/i-2012-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/ats/i-2012-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

DTC Descriptors

For symptom byte information refer to Symptom Byte List .

The brake booster vacuum sensor monitors the pressure in the brake booster. The electronic brake control module supplies a 5 V reference and a low reference circuit to the brake booster vacuum sensor. The vacuum sensor supplies a voltage signal in relation to the pressure in the brake booster to the electronic brake control module.

Ignition ON.

C1100 00

1. A short to ground, short to voltage or open/high resistance is detected on the signal circuit.
2. An open/high resistance is detected on the 5 V reference circuit.
3. An open/high resistance is detected on the low reference circuit.
4. The electronic brake control module detects an erratic vacuum sensor signal.

C1100 01

A short to voltage is detected on the vacuum sensor 5 V reference circuit.

C1100 02

A short to ground is detected on the vacuum sensor 5 V reference circuit.

C1100 09

The vacuum sensor signal too fast transitions.

C1100 5A

The vacuum sensor signal is not plausible.

The brake warning indicator turns ON.

1. A current DTC clears when the diagnostic runs and passes.
2. The electronic control module will turn OFF the indicator in the next ignition cycle.

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»(/cadillac/ats/i-2012-2014/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/cadillac/ats/i-2012-2014/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/ats/i-2012-2014/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/cadillac/ats/i-2012-2014/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the B19B Brake Booster Vacuum Sensor. It may take up to 2 min for all vehicle systems to power down.
2. Test for less than 10 ohms between the low reference circuit terminal 2 and ground. If 10 ohms or greater Disconnect the harness connector at the K17 Electronic Brake Control Module. Test for less than 2 ohms in the low reference circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, replace the K17 Electronic Brake Control Module. If less than 10 ohms
3. Ignition ON.
4. Test for 4.8-5.2 V between the 5 V reference circuit terminal 3 and ground. If less than 4.8 V Ignition OFF, disconnect the harness connector at the K17 Electronic Brake Control Module. Test for infinite resistance between the 5 V reference circuit and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance Test for less than 2 ohms in the 5 V reference circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, replace the K17 Electronic Brake Control Module. If greater than 5.2 V Ignition OFF, disconnect the harness connector at the K17 Electronic Brake Control Module, ignition ON. Test for less than 1 V between the 5 V reference circuit and ground. If 1 V or greater, repair the short to voltage on the circuit. If less than 1 V, replace the K17 Electronic Brake Control Module. If between 4.8-5.2 V
5. Ignition OFF, disconnect the harness connector at the K17 Electronic Brake Control Module, ignition ON.
6. Test for less than 1 V between the B19B Brake Booster Vacuum Sensor signal circuit terminal 1 and ground. If greater than 1 V Repair the short to voltage on the circuit. If less than 1 V
7. Ignition OFF.
8. Test for infinite resistance between the B19B Brake Booster Vacuum Sensor signal circuit terminal 1 and ground. If less than infinite resistance Repair the short to ground on the circuit. If infinite resistance
9. Test for less than 2 ohms between the B19B Brake Booster Vacuum Sensor signal circuit terminal 1 and the K17 Electronic Brake Control Module signal circuit terminal 4. If 2 ohms or greater Repair the open/high resistance in the circuit. If less than 2 ohms
10. Replace the B19B Brake Booster Vacuum Sensor.
11. Verify the DTC does not set while operating the vehicle under Conditions for Running the DTC. If the DTC sets Replace the K17 Electronic Brake Control Module. If the DTC does not set
12. All OK.

Perform the Diagnostic Repair Verification after completing the repair.

1. «Power Vacuum Brake Booster Replacement»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system) for Power Brake Booster Vacuum Sensor Replacement
2. «Control Module References»(/cadillac/ats/i-2012-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for electronic brake control module replacement, programming and setup

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/ats/i-2012-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/ats/i-2012-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/ats/i-2012-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

For symptom byte information refer to Symptom Byte List .

The brake booster vacuum sensor monitors the pressure in the brake booster. The engine control module supplies a 5 V reference and a low reference circuit to the brake booster vacuum sensor. The vacuum sensor supplies a voltage signal in relation to the pressure in the brake booster to the engine control module.

Ignition ON.

The engine control module detects less than 0.04 V on the brake booster sensor signal circuit for more than 12.5 ms.

DTC P0557 is a Type B DTC.

DTC P0557 is a Type B DTC.

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»(/cadillac/ats/i-2012-2014/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/cadillac/ats/i-2012-2014/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/ats/i-2012-2014/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/cadillac/ats/i-2012-2014/remont/body-electrical/#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. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the B19B Brake Booster Vacuum Sensor. It may take up to 2 min for all vehicle systems to power down.
2. Test for less than 10 ohms between the low reference circuit terminal 2 and ground. If 10 ohms or greater Disconnect the harness connector X1 at the K20 Engine Control Module. Test for less than 2 ohms in the low reference circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, replace the K20 Engine Control Module. If less than 10 ohms
3. Ignition ON.
4. Test for 4.8-5.2 V between the 5 V reference circuit terminal 3 and ground. If less than 4.8 V Ignition OFF, disconnect the harness connector X1 at the K20 Engine Control Module. Test for infinite resistance between the 5 V reference circuit and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance Test for less than 2 ohms in the 5 V reference circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, replace the K20 Engine Control Module. If greater than 5.2 V Ignition OFF, disconnect the harness connector X1 at the K20 Engine Control Module, ignition ON. Test for less than 1 V between the 5 V reference circuit and ground. If 1 V or greater, repair the short to voltage on the circuit. If less than 1 V, replace the K20 Engine Control Module. If between 4.8-5.2 V
5. Ignition OFF, disconnect the harness connector X1 at the K20 Engine Control Module, ignition ON.
6. Test for less than 1 V between the B19B Brake Booster Vacuum Sensor signal circuit terminal 1 and ground. If greater than 1 V Repair the short to voltage on the circuit. If less than 1 V
7. Ignition OFF.
8. Test for infinite resistance between the B19B Brake Booster Vacuum Sensor signal circuit terminal 1 and ground. If less than infinite resistance Repair the short to ground on the circuit. If infinite resistance
9. Test for less than 2 ohms between the B19B Brake Booster Vacuum Sensor signal circuit terminal 1 and the K20 Engine Control Module X1 signal circuit terminal 4. If 2 ohms or greater Repair the open/high resistance in the circuit. If less than 2 ohms
10. Replace the B19B Brake Booster Vacuum Sensor.
11. Verify the DTC does not set while operating the vehicle under Conditions for Running the DTC. If the DTC sets Replace the K20 Engine Control Module. If the DTC does not set
12. All OK.

Perform the Diagnostic Repair Verification after completing the repair.

1. «Power Brake Booster Vacuum Check Valve and Hose Replacement (3.6L)»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system) , «Power Brake Booster Vacuum Check Valve and Hose Replacement (2.0L, 2.5L)»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system) for Brake Booster Vacuum Sensor replacement
2. «Control Module References»(/cadillac/ats/i-2012-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for engine control module replacement, programming and setup.

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/ats/i-2012-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/ats/i-2012-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/ats/i-2012-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

For symptom byte information refer to Symptom Byte List .

The brake booster vacuum sensor monitors the pressure in the brake booster. The engine control module supplies a 5 V reference and a low reference circuit to the brake booster vacuum sensor. The vacuum sensor supplies a voltage signal in relation to the pressure in the brake booster to the engine control module.

Ignition ON.

The engine control module detects greater than 4.89 V on the brake booster sensor signal circuit for more than 12.5 ms.

DTC P0558 is a Type B DTC.

DTC P0558 is a Type B DTC.

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»(/cadillac/ats/i-2012-2014/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/cadillac/ats/i-2012-2014/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/ats/i-2012-2014/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/cadillac/ats/i-2012-2014/remont/body-electrical/#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. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the B19B Brake Booster Vacuum Sensor. It may take up to 2 min for all vehicle systems to power down.
2. Test for less than 10 ohms between the low reference circuit terminal 2 and ground. If 10 ohms or greater Disconnect the harness connector X1 at the K20 Engine Control Module. Test for less than 2 ohms in the low reference circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, replace the K20 Engine Control Module. If less than 10 ohms
3. Ignition ON.
4. Test for 4.8-5.2 V between the 5 V reference circuit terminal 3 and ground. If less than 4.8 V Ignition OFF, disconnect the harness connector X1 at the K20 Engine Control Module. Test for infinite resistance between the 5 V reference circuit and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance Test for less than 2 ohms in the 5 V reference circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, replace the K20 Engine Control Module. If greater than 5.2 V Ignition OFF, disconnect the harness connector X1 at the K20 Engine Control Module, ignition ON. Test for less than 1 V between the 5 V reference circuit and ground. If 1 V or greater, repair the short to voltage on the circuit. If less than 1 V, replace the K20 Engine Control Module. If between 4.8-5.2 V
5. Ignition OFF, disconnect the harness connector X1 at the K20 Engine Control Module, ignition ON.
6. Test for less than 1 V between the B19B Brake Booster Vacuum Sensor signal circuit terminal 1 and ground. If greater than 1 V Repair the short to voltage on the circuit. If less than 1 V
7. Ignition OFF.
8. Test for infinite resistance between the B19B Brake Booster Vacuum Sensor signal circuit terminal 1 and ground. If less than infinite resistance Repair the short to ground on the circuit. If infinite resistance
9. Test for less than 2 ohms between the B19B Brake Booster Vacuum Sensor signal circuit terminal 1 and the K20 Engine Control Module X1 signal circuit terminal 4. If 2 ohms or greater Repair the open/high resistance in the circuit. If less than 2 ohms
10. Replace the B19B Brake Booster Vacuum Sensor.
11. Verify the DTC does not set while operating the vehicle under Conditions for Running the DTC. If the DTC sets Replace the K20 Engine Control Module. If the DTC does not set
12. All OK.

Perform the Diagnostic Repair Verification after completing the repair.

1. «Power Brake Booster Vacuum Check Valve and Hose Replacement (3.6L)»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system) , «Power Brake Booster Vacuum Check Valve and Hose Replacement (2.0L, 2.5L)»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system) for Brake Booster Vacuum Sensor replacement
2. «Control Module References»(/cadillac/ats/i-2012-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for engine control module replacement, programming and setup.

Symptoms - Hydraulic Brakes

Note. The following steps must be completed before using the symptom tables.

1. Perform the «Brake System Vehicle Road Test»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system) before using the hydraulic brake symptom tables in order to duplicate the customers concern.
2. Review the system operation in order to familiarize yourself with the system functions. Refer to the following: «Brake Warning System Description and Operation»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system) «Hydraulic Brake System Description and Operation»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system) «Brake Booster Vacuum Assist Description and Operation»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system) «Brake Assist System Description and Operation»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system) «ABS Description and Operation»(/cadillac/ats/i-2012-2014/remont/anti-locktraction-control/#antilock-brake-system__abs-description-and-operation)

Visual/Physical Inspection

1. Inspect for aftermarket devices which could affect the operation of the hydraulic brake system. Refer to «Checking Aftermarket Accessories»(/cadillac/ats/i-2012-2014/remont/body-electrical/#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 Booster Pump Motor Malfunction»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system)
2. «Brake Warning Indicator Malfunction»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system)
3. «Brake Pulsation»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system__brake-pulsation)
4. «Brake System Noise»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system__brake-system-noise)
5. «Braking Action Uneven - Pulls to One Side»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system)
6. «Braking Action Uneven - Front to Rear»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system)
7. «Brake Pedal Excessive Travel»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system__brake-pedal-excessive-travel)
8. «Brake Pedal Excessive Effort»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system__brake-pedal-excessive-effort)
9. «Brakes Drag»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system__brakes-drag)
10. «Brake System Slow Release»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system__brake-system-slow-release)
11. «Brake Fluid Loss»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system__brake-fluid-loss)

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/ats/i-2012-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/ats/i-2012-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/ats/i-2012-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The brake booster vacuum sensor measures the vacuum in the brake booster assembly. The electronic brake control module supplies a 5 V reference and a low reference circuit to the brake booster vacuum sensor. The vacuum sensor supplies a voltage signal in relation to the pressure in the brake booster to the electronic brake control module. When the vacuum within the system becomes weak, the electronic brake control module turns ON the brake booster pump motor by providing ground to the brake booster pump motor relay. The relay activates and supplies battery voltage to the brake booster pump motor.

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»(/cadillac/ats/i-2012-2014/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/cadillac/ats/i-2012-2014/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/ats/i-2012-2014/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/cadillac/ats/i-2012-2014/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References

1. Ignition ON.
2. Verify that DTC C1100 is not set. If the DTC is set Refer to «DTC C1100»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system) . If the DTC is not set
3. Verify the M9 Brake Booster Pump Motor turns ON and OFF when commanding the Brake Booster Electric Vacuum Pump On and Off with a scan tool. If the M9 Brake Booster Pump Motor does not turn ON and OFF Refer to Circuit/System Testing. If the M9 Brake Booster Pump Motor turn ON and OFF
4. Verify that the brake booster vacuum system has no damage, leakage or incorrect installation. If damage, leakage or incorrect installation is found Refer to «Brake Assist System Diagnosis»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system__brake-assist-system-diagnosis) . If the inspection is OK
5. All OK.

1. Ignition OFF, disconnect the KR14 Brake Booster Pump Motor Relay, ignition ON.
2. Verify a test lamp illuminates between the B+ circuit terminal 30 and ground. If the test lamp does not illuminate and the circuit fuse is good Ignition OFF, remove the test lamp. Test for less than 2 ohms in the B+ circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, verify the fuse is not open and there is voltage at the fuse. If the test lamp does not illuminate and the circuit fuse is open Ignition OFF, remove the test lamp. Test for infinite resistance between the B+ circuit and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance, Disconnect the M9 Brake Booster Pump Motor. Test for greater than 10 ohms between the control circuit terminal 87 and ground. If less than 10 ohms, repair the short to ground on the circuit. If greater than 10 ohms, test or replace the M9 Brake Booster Pump Motor. If the test lamp illuminates
3. Ignition OFF and all vehicle systems OFF. It may take up to 2 min for all vehicle systems to power down.
4. Test for less than 10 ohms between the ground circuit terminal 86 and ground. If 10 ohms or greater Ignition OFF. Test for less than 2 ohms in the ground circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, repair the open/high resistance in the ground connection. If less than 10 ohms
5. Connect a test lamp between the control circuit terminal 85 and the ground circuit terminal 86.
6. Verify the test lamp turns ON and OFF when commanding the Brake Booster Pump Motor On and Off with a scan tool. If the test lamp is always OFF Ignition OFF, remove the test lamp, disconnect the harness connector at the K17 Electronic Brake Control Module, ignition ON. Test for infinite resistance between the control circuit and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance Test for less than 2 ohms in the control circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, replace the K17 Electronic Brake Control Module. If the test lamp is always ON Ignition OFF, remove the test lamp, disconnect the harness connector at the K17 Electronic Brake Control Module. Test for less than 1 V between the control circuit and ground. If 1 V or greater, repair the short to voltage on the circuit. If less than 1 V, replace the K17 Electronic Brake Control Module. If the test lamp turns ON and OFF
7. Verify a test lamp does not illuminate between the control circuit terminal 87 and ground. If the test lamp illuminates Repair the short to voltage on the circuit. If the test lamp does not illuminate
8. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the M9 Brake Booster Pump Motor. It may take up to 2 minutes for all vehicle systems to power down.
9. Test for less than 10 ohms between the M9 Brake Booster Pump Motor ground circuit terminal 2 and ground. If 10 ohms or greater Ignition OFF. Test for less than 2 ohms in the ground circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, repair the open/high resistance in the ground connection. If less than 10 ohms
10. Connect the harness connector at the M9 Brake Booster Pump Motor.
11. Ignition ON, connect a 30 A fused jumper wire between the B+ circuit terminal 30 and the control circuit terminal 87.
12. Verify the M9 Brake Booster Pump Motor is activated. If the M9 Brake Booster Pump Motor does not activate Ignition OFF, remove the jumper wire. Test for less than 2 ohms in the control circuit terminal 87 end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, test or replace the M9 Brake Booster Pump Motor. If the M9 Brake Booster Pump Motor activates
13. Test or replace the KR14 Brake Booster Pump Motor Relay.

Relay Test

1. Ignition OFF, remove the KR14 Brake Booster Pump Motor Relay.
2. Test for 70-150 ohms between terminals 85 and 86. If less than 70 ohms or greater than 150 ohms Replace the KR14 Brake Booster Pump Motor Relay. If between 70-150 ohms
3. Test for infinite resistance between the terminals listed below: 30 and 86 30 and 87 30 and 85 85 and 87 If less than infinite resistance Replace the KR14 Brake Booster Pump Motor Relay. If infinite resistance
4. Install a 30 A fused jumper wire between relay terminal 85 and 12 V. Install a jumper wire between relay terminal 86 and ground.
5. Test for less than 10 ohms between terminals 30 and 87. If 10 ohms or greater Replace the KR14 Brake Booster Pump Motor Relay. If less than 10 ohms
6. All OK.

Perform the Diagnostic Repair Verification after completing the repair.

1. «Power Brake Booster Pump Replacement (3.6L)»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system) , «Power Brake Booster Pump Replacement (2.0L, 2.5L)»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system)
2. «Control Module References»(/cadillac/ats/i-2012-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for electronic brake control module replacement, programming and setup.

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/ats/i-2012-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/ats/i-2012-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/ats/i-2012-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The electronic brake control module monitors the brake fluid level in the brake fluid reservoir. When the fluid within the brake fluid reservoir is below the MIN level, contacts within the brake fluid level switch closes causing the voltage within the signal circuit to drop. The electronic brake control module will detect the voltage drop and will send a serial data message to the instrument cluster commanding the brake warning indicator to illuminate.

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»(/cadillac/ats/i-2012-2014/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/cadillac/ats/i-2012-2014/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/ats/i-2012-2014/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/cadillac/ats/i-2012-2014/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

1. Verify that the brake fluid level is above the minimum level. If low Refer to «Brake Fluid Loss»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system__brake-fluid-loss) . If above minimum level
2. Ignition ON.
3. Verify the scan tool Brake Fluid Level Sensor parameter is OK. If the parameter is Low Refer to Circuit/System Testing If the parameter is Ok
4. Verify the brake warning indicator turns ON and OFF when commanding the Instrument Cluster All Indicators On and Off with a scan tool. If the brake warning indicator does not turn ON and OFF Replace the P16 Instrument Cluster. If the brake warning indicator turns ON and OFF
5. All OK.

1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the B20 Brake Fluid Level Switch. It may take up to 2 min for all vehicle systems to power down.
2. Test for less than 10 ohms between the ground circuit terminal 2 and ground. If 10 ohms or greater Ignition OFF. Test for less than 2 ohms in the ground circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, repair the open/high resistance in the ground connection. If less than 10 ohms
3. Ignition ON.
4. Verify the scan tool Brake Fluid Level Sensor parameter is OK. If the parameter is not OK Ignition OFF, disconnect the harness connector at the K17 Electronic Brake Control Module. Test for infinite resistance between the signal circuit terminal 1 and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance, replace the K17 Electronic Brake Control Module. If the parameter is OK
5. Install a 3 A fused jumper wire between the signal circuit terminal 1 and ground.
6. Verify the scan tool Brake Fluid Level Sensor parameter is Low. If the parameter is OK Ignition OFF, disconnect the harness connector at the K17 Electronic Brake Control Module, ignition ON. Test for less than 1 V between the signal circuit and ground. If 1 V or greater, repair the short to voltage on the circuit. If less than 1 V. Test for less than 2 ohms in the signal circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, replace the K17 Electronic Brake Control Module. If the parameter is Low
7. Test or replace the B20 Brake Fluid Level Switch.

Perform the Diagnostic Repair Verification after completing the repair.

1. «Brake Fluid Level Indicator Switch Replacement»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system)
2. «Control Module References»(/cadillac/ats/i-2012-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for electronic brake control module and Instrument Cluster replacement, programming and setup.

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»(/cadillac/ats/i-2012-2014/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»(/cadillac/ats/i-2012-2014/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

CH-28662 Brake Pedal Effort Gauge

For equivalent regional tools, refer to Special Tools .

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 CH-28662 gauge (1), or equivalent, to the brake pedal (3).
3. Measure and record the distance (a) from the brake pedal (3) to the rim of the steering wheel (2). Note the points of measurement.
4. Apply and maintain a force of 445 N (100 lb) to the brake pedal, as indicated on the CH-28662 gauge (1), or equivalent.
5. While maintaining 445 N (100 lb) of force to the brake pedal (3), measure and record the distance (b) from the same point on the brake pedal (3) to the same point on the rim of the steering wheel (2).
6. Release the brake pedal (3) 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 for the 2 applies of the brakes.
8. Subtract the initial unapplied distance (a), from the average applied distance (b) to obtain the brake pedal travel measurement (c).
9. Compare the measurement obtained with the specification. Refer to «Brake System Specifications»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system__brake-system-specifications) .

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. If the fluid level is abnormally low, adjust the brake fluid level. Refer to «Master Cylinder Reservoir Filling»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system__master-cylinder-reservoir-filling) .
2. Start the engine and allow it to idle.
3. 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.
4. Turn OFF the ignition.
5. 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
6. 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»(/cadillac/ats/i-2012-2014/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)»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system) , «Hydraulic Brake System Bleeding (Pressure)»(/cadillac/ats/i-2012-2014/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)»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system) , «Hydraulic Brake System Bleeding (Pressure)»(/cadillac/ats/i-2012-2014/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.

Removal Procedure

1. Using a suitable tool, remove and properly discard the brake fluid from the master cylinder reservoir.
2. Remove the brake fluid level indicator switch. Refer to «Brake Fluid Level Indicator Switch Replacement»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system) .
3. Remove the master cylinder reservoir bolt (1).
4. Lift the master cylinder reservoir (1) upward to release the reservoir from the reservoir seals and the master cylinder.
5. Remove the 2 master cylinder reservoir seals (1).

Installation Procedure

1. Lubricate the master cylinder reservoir seals with GM approved brake fluid from a clean, sealed, brake fluid container.
2. Install the 2 master cylinder reservoir seals (1).
3. Firmly and squarely press the master cylinder reservoir (1) into the master cylinder.
4. Install the master cylinder reservoir bolt (1) and tighten to 8 (71 lb in).
5. Install the brake fluid level indicator switch. Refer to «Brake Fluid Level Indicator Switch Replacement»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system) .
6. Fill the master cylinder reservoir. Refer to «Master Cylinder Reservoir Filling»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system__master-cylinder-reservoir-filling) .

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 power vacuum brake booster vacuum reserve.
3. Using a suitable tool, remove and properly dispose of the brake fluid from the master cylinder reservoir.
4. Disconnect the brake fluid level indicator switch electrical connector.
5. Disconnect the brake pressure modulator valve secondary brake pipe fitting (1).
6. Cap the brake pipe fitting to prevent brake fluid loss and contamination.
7. Disconnect the brake pressure modulator valve primary brake pipe fitting (1).
8. Cap the brake pipe fitting to prevent brake fluid loss and contamination.
9. Remove and discard the master cylinder nuts (1).
10. Remove the master cylinder.

1. If installing a new master cylinder, bench bleed the master cylinder. Refer to «Master Cylinder Bench Bleeding»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system__master-cylinder-bench-bleeding) .
2. Install the master cylinder.
3. Install new master cylinder nuts (1) and tighten to 23 (17 lb ft).
4. Connect the brake pressure modulator valve primary brake pipe fitting (1) and tighten to 30 (22 lb ft).
5. Connect the brake pressure modulator valve secondary brake pipe fitting (1) and tighten to 30 (22 lb ft).
6. Connect the brake fluid level indicator switch electrical connector.
7. Bleed the hydraulic brake system. Refer to «Hydraulic Brake System Bleeding (Manual)»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system) , «Hydraulic Brake System Bleeding (Pressure)»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system) .

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»(/cadillac/ats/i-2012-2014/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.

1. Disconnect the brake fluid level indicator switch electrical connector.
2. Compress the locking tabs on the inboard side of the master cylinder reservoir and remove the brake fluid level indicator switch (1).

1. Install the brake fluid level indicator switch (1).
2. Ensure the locking tabs of the brake fluid level indicator switch are fully engaged in the master cylinder reservoir.
3. Connect the brake fluid level indicator switch electrical connector.

1. Remove the instrument panel tie bar (1). Refer to «Instrument Panel Tie Bar Replacement»(/cadillac/ats/i-2012-2014/remont/exteriorinterior-trim/#instrument-panel-trim-and-console-trim) .
2. Remove the brake pedal position sensor (1). Refer to «Brake Pedal Position Sensor Replacement»(/cadillac/ats/i-2012-2014/remont/exterior-lights/#lighting-system-repair-instructions__brake-pedal-position-sensor-replacement) .
3. Pull the brake pedal (1) rearward to release the power vacuum brake booster pushrod retainer.
4. Remove and discard the power vacuum brake booster pushrod retainer (1).
5. Remove the power vacuum brake booster nuts (1).
6. Remove the brake pedal assembly nuts (1).
7. Remove the brake pedal assembly.

1. Install the brake pedal assembly.
2. Install the brake pedal assembly nuts (1) and tighten to 25 (18 lb ft).
3. Install the power vacuum brake booster nuts (1) and tighten to 25 (18 lb ft).
4. Install a new power vacuum brake booster pushrod retainer (1) to the brake pedal.
5. Install the brake pedal (1) to the power vacuum brake booster pushrod.
6. Install the brake pedal position sensor (1). Refer to «Brake Pedal Position Sensor Replacement»(/cadillac/ats/i-2012-2014/remont/exterior-lights/#lighting-system-repair-instructions__brake-pedal-position-sensor-replacement) .
7. Install the instrument panel tie bar (1). Refer to «Instrument Panel Tie Bar Replacement»(/cadillac/ats/i-2012-2014/remont/exteriorinterior-trim/#instrument-panel-trim-and-console-trim) .

1. Remove the instrument panel tie bar (1). Refer to «Instrument Panel Tie Bar Replacement»(/cadillac/ats/i-2012-2014/remont/exteriorinterior-trim/#instrument-panel-trim-and-console-trim) .
2. Remove the brake pedal position sensor (1). Refer to «Brake Pedal Position Sensor Replacement»(/cadillac/ats/i-2012-2014/remont/exterior-lights/#lighting-system-repair-instructions__brake-pedal-position-sensor-replacement) .
3. Pull the brake pedal (1) rearward to release the power vacuum brake booster pushrod retainer.
4. Remove and discard the power vacuum brake booster pushrod retainer (1).
5. Disconnect the clutch master cylinder pushrod retainer (1), remove the nuts and position aside the clutch master cylinder (2). Refer to «Clutch Pedal Replacement»(/cadillac/ats/i-2012-2014/remont/clutches-manual-hydraulic/#manual-transmission-clutch) .
6. Remove the power vacuum brake booster nuts (1).
7. Remove the brake pedal assembly nuts (1).
8. Remove the brake pedal assembly.

1. Install the brake pedal assembly.
2. Install the brake pedal assembly nuts (1) and tighten to 25 (18 lb ft).
3. Install the power vacuum brake booster nuts (1) and tighten to 25 (18 lb ft).
4. Connect the clutch master cylinder pushrod retainer (1) and install the clutch master cylinder (2). Refer to «Clutch Pedal Replacement»(/cadillac/ats/i-2012-2014/remont/clutches-manual-hydraulic/#manual-transmission-clutch) .
5. Install a new power vacuum brake booster pushrod retainer (1) to the brake pedal.
6. Install the brake pedal (1) to the power vacuum brake booster pushrod.
7. Install the brake pedal position sensor (1). Refer to «Brake Pedal Position Sensor Replacement»(/cadillac/ats/i-2012-2014/remont/exterior-lights/#lighting-system-repair-instructions__brake-pedal-position-sensor-replacement) .
8. Install the instrument panel tie bar (1). Refer to «Instrument Panel Tie Bar Replacement»(/cadillac/ats/i-2012-2014/remont/exteriorinterior-trim/#instrument-panel-trim-and-console-trim) .

1. Remove the plenum front panel. Refer to «Plenum Front Panel Replacement»(/cadillac/ats/i-2012-2014/remont/exteriorinterior-trim/#bolted-exterior-body-panels-and-closures) .
2. If equipped with the 2.0L or 2.5L engine, remove the outer fuel pump insulator. Refer to «Fuel Pump Insulator Replacement (Outer)»(/cadillac/ats/i-2012-2014/remont/testing-diagnostics/#engine-controlsfuel-20l-ltg-or-25l-lcv-repair-instructions) .
3. If equipped with the 3.6L engine, remove the intake manifold insulator. Refer to «Intake Manifold Insulator Replacement»(/cadillac/ats/i-2012-2014/remont/mechanical/#engine-mechanical-36l-lfx-repair-instructions-on-vehicle) .
4. Disconnect the heater inlet pipe from the heater core only. Refer to «Heater Inlet Hose Replacement (LFX)»(/cadillac/ats/i-2012-2014/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning) , «Heater Inlet Hose Replacement (LCV, LTG)»(/cadillac/ats/i-2012-2014/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning) .
5. Disconnect the heater outlet pipe from the heater core only. Refer to «Heater Outlet Hose Replacement (LFX)»(/cadillac/ats/i-2012-2014/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning) , «Heater Outlet Hose Replacement (LCV)»(/cadillac/ats/i-2012-2014/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning) , «Heater Outlet Hose Replacement (LTG with KL9)»(/cadillac/ats/i-2012-2014/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning) , «Heater Outlet Hose Replacement (LTG without KL9)»(/cadillac/ats/i-2012-2014/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning) .
6. Without removing the steering shafts from the vehicle, separate the upper intermediate steering shaft from the mid intermediate steering shaft. Refer to «Upper Intermediate Steering Shaft Replacement (RWD)»(/cadillac/ats/i-2012-2014/remont/steering-column-switches/#steering-wheel-and-steering-column) , «Upper Intermediate Steering Shaft Replacement (AWD)»(/cadillac/ats/i-2012-2014/remont/steering-column-switches/#steering-wheel-and-steering-column) .
7. Using a suitable tool, remove and properly dispose of the brake fluid from the master cylinder reservoir.
8. Disconnect the brake pressure modulator valve primary brake pipe fitting (1) at the master cylinder.
9. Plug the master cylinder outlet port to prevent brake fluid loss and contamination.
10. Remove the air conditioning evaporator hose assembly. Refer to «Air Conditioning Evaporator Hose Assembly Replacement»(/cadillac/ats/i-2012-2014/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning) .
11. Release the brake pipe from the retaining clips (1).
12. Release the brake pipe from the retaining clips (1) on the cowl.
13. Release the brake pipe from the retaining clip (1).
14. Disconnect the brake pressure modulator valve primary brake pipe fitting (1) at the brake pressure modulator valve (BPMV).
15. Plug the BPMV inlet port to prevent brake fluid loss and contamination.
16. Remove the brake pressure modulator valve primary brake pipe.

1. Install the brake pressure modulator valve primary brake pipe.
2. Connect the brake pressure modulator valve primary brake pipe fitting (1) at the BPMV and tighten the fitting to 32 (24 lb ft).
3. Secure the brake pipe to the retaining clip (1).
4. Secure the brake pipe to the retaining clips (1) on the cowl.
5. Secure the brake pipe to the retaining clips (1).
6. Install the air conditioning evaporator hose assembly. Refer to «Air Conditioning Evaporator Hose Assembly Replacement»(/cadillac/ats/i-2012-2014/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning) .
7. Connect the brake pressure modulator valve primary brake pipe fitting (1) at the master cylinder and tighten the fitting to 30 (22 lb ft).
8. Install the upper intermediate steering shaft to the mid intermediate steering shaft. Refer to «Upper Intermediate Steering Shaft Replacement (RWD)»(/cadillac/ats/i-2012-2014/remont/steering-column-switches/#steering-wheel-and-steering-column) , «Upper Intermediate Steering Shaft Replacement (AWD)»(/cadillac/ats/i-2012-2014/remont/steering-column-switches/#steering-wheel-and-steering-column) .
9. Connect the heater outlet pipe to the heater core. Refer to «Heater Outlet Hose Replacement (LFX)»(/cadillac/ats/i-2012-2014/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning) , «Heater Outlet Hose Replacement (LCV)»(/cadillac/ats/i-2012-2014/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning) , «Heater Outlet Hose Replacement (LTG with KL9)»(/cadillac/ats/i-2012-2014/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning) , «Heater Outlet Hose Replacement (LTG without KL9)»(/cadillac/ats/i-2012-2014/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning) .
10. Connect the heater inlet pipe to the heater core. Refer to «Heater Inlet Hose Replacement (LFX)»(/cadillac/ats/i-2012-2014/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning) , «Heater Inlet Hose Replacement (LCV, LTG)»(/cadillac/ats/i-2012-2014/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning) .
11. If equipped with the 3.6L engine, install the intake manifold insulator. Refer to «Intake Manifold Insulator Replacement»(/cadillac/ats/i-2012-2014/remont/mechanical/#engine-mechanical-36l-lfx-repair-instructions-on-vehicle) .
12. If equipped with the 2.0L or 2.5L engine, install the outer fuel pump insulator. Refer to «Fuel Pump Insulator Replacement (Inner)»(/cadillac/ats/i-2012-2014/remont/testing-diagnostics/#engine-controlsfuel-20l-ltg-or-25l-lcv-repair-instructions) , «Fuel Pump Insulator Replacement (Outer)»(/cadillac/ats/i-2012-2014/remont/testing-diagnostics/#engine-controlsfuel-20l-ltg-or-25l-lcv-repair-instructions) .
13. Install the plenum front panel. Refer to «Plenum Front Panel Replacement»(/cadillac/ats/i-2012-2014/remont/exteriorinterior-trim/#bolted-exterior-body-panels-and-closures) .
14. Bleed the hydraulic brake system. Refer to «Hydraulic Brake System Bleeding (Manual)»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system) , «Hydraulic Brake System Bleeding (Pressure)»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system) .

1. Remove the plenum front panel. Refer to «Plenum Front Panel Replacement»(/cadillac/ats/i-2012-2014/remont/exteriorinterior-trim/#bolted-exterior-body-panels-and-closures) .
2. If equipped with the 2.0L or 2.5L engine, remove the outer fuel pump insulator. Refer to «Fuel Pump Insulator Replacement (Outer)»(/cadillac/ats/i-2012-2014/remont/testing-diagnostics/#engine-controlsfuel-20l-ltg-or-25l-lcv-repair-instructions) .
3. If equipped with the 3.6L engine, remove the intake manifold insulator. Refer to «Intake Manifold Insulator Replacement»(/cadillac/ats/i-2012-2014/remont/mechanical/#engine-mechanical-36l-lfx-repair-instructions-on-vehicle) .
4. Disconnect the heater inlet pipe from only the heater core. Refer to «Heater Inlet Hose Replacement (LFX)»(/cadillac/ats/i-2012-2014/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning) , «Heater Inlet Hose Replacement (LCV, LTG)»(/cadillac/ats/i-2012-2014/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning) .
5. Disconnect the heater outlet pipe from only the heater core. Refer to «Heater Outlet Hose Replacement (LFX)»(/cadillac/ats/i-2012-2014/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning) , «Heater Outlet Hose Replacement (LCV)»(/cadillac/ats/i-2012-2014/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning) , «Heater Outlet Hose Replacement (LTG with KL9)»(/cadillac/ats/i-2012-2014/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning) , «Heater Outlet Hose Replacement (LTG without KL9)»(/cadillac/ats/i-2012-2014/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning) .
6. Without removing the steering shafts from the vehicle, separate the upper intermediate steering shaft from the mid intermediate steering shaft. Refer to «Upper Intermediate Steering Shaft Replacement (RWD)»(/cadillac/ats/i-2012-2014/remont/steering-column-switches/#steering-wheel-and-steering-column) , «Upper Intermediate Steering Shaft Replacement (AWD)»(/cadillac/ats/i-2012-2014/remont/steering-column-switches/#steering-wheel-and-steering-column) .
7. Using a suitable tool, remove and properly dispose of the brake fluid from the master cylinder reservoir.
8. Disconnect the brake pressure modulator valve secondary brake pipe fitting (1) at the master cylinder.
9. Plug the master cylinder outlet port to prevent brake fluid loss and contamination.
10. Remove the air conditioning evaporator hose assembly. Refer to «Air Conditioning Evaporator Hose Assembly Replacement»(/cadillac/ats/i-2012-2014/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning) .
11. Release the brake pipe from the retaining clips (1).
12. Release the brake pipe from the retaining clips (1) on the cowl.
13. Release the brake pipe from the retaining clip (1).
14. Disconnect the brake pressure modulator valve secondary brake pipe fitting (1) at the brake pressure modulator valve (BPMV).
15. Plug the BPMV inlet port to prevent brake fluid loss and contamination.
16. Remove the brake pressure modulator valve secondary brake pipe.

1. Install the brake pressure modulator valve secondary brake pipe.
2. Connect the brake pressure modulator valve secondary brake pipe fitting (1) at the BPMV and tighten the fitting to 32 (24 lb ft).
3. Secure the brake pipe to the retaining clip (1).
4. Secure the brake pipe to the retaining clips (1) on the cowl.
5. Secure the brake pipe to the retaining clips (1).
6. Install the air conditioning evaporator hose assembly. Refer to «Air Conditioning Evaporator Hose Assembly Replacement»(/cadillac/ats/i-2012-2014/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning) .
7. Connect the brake pressure modulator valve secondary brake pipe fitting (1) at the master cylinder and tighten the fitting to 30 (22 lb ft).
8. Install the upper intermediate steering shaft to the mid intermediate steering shaft. Refer to «Upper Intermediate Steering Shaft Replacement (RWD)»(/cadillac/ats/i-2012-2014/remont/steering-column-switches/#steering-wheel-and-steering-column) , «Upper Intermediate Steering Shaft Replacement (AWD)»(/cadillac/ats/i-2012-2014/remont/steering-column-switches/#steering-wheel-and-steering-column) .
9. Connect the heater outlet pipe to the heater core. Refer to «Heater Outlet Hose Replacement (LFX)»(/cadillac/ats/i-2012-2014/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning) , «Heater Outlet Hose Replacement (LCV)»(/cadillac/ats/i-2012-2014/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning) , «Heater Outlet Hose Replacement (LTG with KL9)»(/cadillac/ats/i-2012-2014/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning) , «Heater Outlet Hose Replacement (LTG without KL9)»(/cadillac/ats/i-2012-2014/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning) .
10. Connect the heater inlet pipe to the heater core. Refer to «Heater Inlet Hose Replacement (LFX)»(/cadillac/ats/i-2012-2014/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning) , «Heater Inlet Hose Replacement (LCV, LTG)»(/cadillac/ats/i-2012-2014/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning) .
11. If equipped with the 3.6L engine, install the intake manifold insulator. Refer to «Intake Manifold Insulator Replacement»(/cadillac/ats/i-2012-2014/remont/mechanical/#engine-mechanical-36l-lfx-repair-instructions-on-vehicle) .
12. If equipped with the 2.0L or 2.5L engine, install the outer fuel pump insulator. Refer to «Fuel Pump Insulator Replacement (Outer)»(/cadillac/ats/i-2012-2014/remont/testing-diagnostics/#engine-controlsfuel-20l-ltg-or-25l-lcv-repair-instructions) .
13. Install the plenum front panel. Refer to «Plenum Front Panel Replacement»(/cadillac/ats/i-2012-2014/remont/exteriorinterior-trim/#bolted-exterior-body-panels-and-closures) .
14. Bleed the hydraulic brake system. Refer to «Hydraulic Brake System Bleeding (Manual)»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system) , «Hydraulic Brake System Bleeding (Pressure)»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system) .

Brake Pipe Replacement

Special Tools

CH-45405 Brake Pipe Flaring Tool Kit

For equivalent regional tools, refer to Special Tools .

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 CH-45405 Brake 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 CH-45405 Brake 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 CH-45405 Brake 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 CH-45405 Brake Pipe Flaring Tool Kit.
11. Install the tube nuts on the brake pipe, noting their orientation.
12. Clean the brake pipe and the CH-45405 Brake Pipe Flaring Tool Kit of lubricant, contaminants, and debris.
13. Loosen the die clamping screw of the CH-45405 Brake 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 CH-45405 Brake 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 CH-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 CH-45405 Brake 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 CH-45405 Brake 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. NOTE: When installing the pipe, maintain a clearance of 19 mm (3/4 in) from all moving or vibrating components.
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)»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system) , «Hydraulic Brake System Bleeding (Pressure)»(/cadillac/ats/i-2012-2014/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.

1. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/cadillac/ats/i-2012-2014/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) .
2. Remove the tire and wheel assembly. Refer to «Tire and Wheel Removal and Installation»(/cadillac/ats/i-2012-2014/remont/wheel-tire-system/#tires-and-wheels__tire-and-wheel-removal-and-installation) .
3. Disconnect the brake pipe fitting (1) from the brake hose.
4. Cap the brake pipe fitting to prevent brake fluid loss and contamination.
5. Remove the brake hose retaining clip (1).
6. Release the brake hose from the wheel speed sensor harness clips (1).
7. Remove the brake hose bracket bolt (1).
8. Remove the brake hose fitting bolt (1).
9. Remove and discard the brake hose fitting gaskets (2) from the brake hose fitting (3).
10. Remove the brake hose.

1. Install the brake hose.
2. Assemble the brake hose fitting bolt (1) with new brake hose fitting gaskets (2) to the brake hose fitting (3).
3. Install the brake hose assembly to the brake caliper and tighten the brake hose fitting bolt to 52 (38 lb ft).
4. Install the brake hose bracket bolt (1) and tighten to 10 (89 lb in).
5. Secure the brake to from the wheel speed sensor harness clips (1).
6. Install the brake hose retaining clip (1).
7. Connect the brake pipe fitting (1) to the brake hose.
8. Tighten the brake pipe fitting to 18 (13 lb ft).
9. Bleed the hydraulic brake system. Refer to «Hydraulic Brake System Bleeding (Manual)»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system) , «Hydraulic Brake System Bleeding (Pressure)»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system) .
10. Install the tire and wheel assembly. Refer to «Tire and Wheel Removal and Installation»(/cadillac/ats/i-2012-2014/remont/wheel-tire-system/#tires-and-wheels__tire-and-wheel-removal-and-installation) .

1. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/cadillac/ats/i-2012-2014/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) .
2. Remove the tire and wheel assembly. Refer to «Tire and Wheel Removal and Installation»(/cadillac/ats/i-2012-2014/remont/wheel-tire-system/#tires-and-wheels__tire-and-wheel-removal-and-installation) .
3. Disconnect the brake pipe fitting (1) from the brake hose.
4. Cap the brake pipe fitting to prevent brake fluid loss and contamination.
5. Remove the brake hose retaining clip (1).
6. Release the brake hose from the wheel speed sensor harness clips (1).
7. Remove the brake hose bracket bolt (1).
8. Remove the brake hose fitting bolt (1).
9. Remove and discard the brake hose fitting gaskets (2) from the brake hose fitting (3).
10. Remove the brake hose.

1. Install the brake hose.
2. Assemble the brake hose fitting bolt (1) with new brake hose fitting gaskets (2) to the brake hose fitting (3).
3. Install the brake hose assembly to the brake caliper and tighten the brake hose fitting bolt to 52 (38 lb ft).
4. Install the brake hose bracket bolt (1) and tighten to 10 (89 lb in).
5. Secure the brake to from the wheel speed sensor harness clips (1).
6. Install the brake hose retaining clip (1).
7. Connect the brake pipe fitting (1) to the brake hose.
8. Tighten the brake pipe fitting to 18 (13 lb ft).
9. Bleed the hydraulic brake system. Refer to «Hydraulic Brake System Bleeding (Manual)»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system) , «Hydraulic Brake System Bleeding (Pressure)»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system) .
10. Install the tire and wheel assembly. Refer to «Tire and Wheel Removal and Installation»(/cadillac/ats/i-2012-2014/remont/wheel-tire-system/#tires-and-wheels__tire-and-wheel-removal-and-installation) .

1. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/cadillac/ats/i-2012-2014/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) .
2. Remove the tire and wheel assembly. Refer to «Tire and Wheel Removal and Installation»(/cadillac/ats/i-2012-2014/remont/wheel-tire-system/#tires-and-wheels__tire-and-wheel-removal-and-installation) .
3. Disconnect the brake pipe fitting (1) from the brake hose.
4. Cap the brake pipe fitting to prevent brake fluid loss and contamination.
5. Remove the brake hose retaining clip (1).
6. Remove and discard the brake hose fitting gaskets (1) by removing the brake hose fitting bolt (2) from the brake hose fitting (3).
7. Remove the brake hose from the vehicle.

1. Install the brake hose to the vehicle.
2. Assemble new brake hose fitting gaskets (1) to the brake hose fitting bolt (2) and the brake hose fitting (3).
3. Install the brake hose assembly to the brake caliper and tighten the brake hose fitting bolt to 49 (36 lb ft).
4. Install the brake hose retaining clip (1).
5. Connect the brake pipe fitting (1) to the brake hose.
6. Tighten the brake pipe fitting to 18 (13 lb ft).
7. Bleed the hydraulic brake system. Refer to «Hydraulic Brake System Bleeding (Manual)»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system) , «Hydraulic Brake System Bleeding (Pressure)»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system) .
8. Install the tire and wheel assembly. Refer to «Tire and Wheel Removal and Installation»(/cadillac/ats/i-2012-2014/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»(/cadillac/ats/i-2012-2014/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»(/cadillac/ats/i-2012-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__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»(/cadillac/ats/i-2012-2014/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»(/cadillac/ats/i-2012-2014/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»(/cadillac/ats/i-2012-2014/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»(/cadillac/ats/i-2012-2014/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»(/cadillac/ats/i-2012-2014/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»(/cadillac/ats/i-2012-2014/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»(/cadillac/ats/i-2012-2014/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»(/cadillac/ats/i-2012-2014/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)»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system) , «Hydraulic Brake System Bleeding (Pressure)»(/cadillac/ats/i-2012-2014/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»(/cadillac/ats/i-2012-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__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»(/cadillac/ats/i-2012-2014/remont/lubrication-system/#maintenance-and-lubrication__fluid-and-lubricant-recommendations) .
5. Following the brake pressure bleeder manufacturer's 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 manufacturer's 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. Install a proper box-end wrench onto the wheel hydraulic circuit bleeder valve which has been serviced.
11. Install a transparent hose over the end of the bleeder valve.
12. Submerge the open end of the transparent hose into a transparent container partially filled with brake fluid from a clean, sealed brake fluid container.
13. Loosen the bleeder valve to purge air from the wheel hydraulic circuit.
14. Allow fluid to flow until air bubbles stop flowing from the bleeder.
15. After all air has been purged from the hydraulic circuit, tighten the bleeder valve and install the dust cap.
16. Close the brake pressure bleeder fluid tank valve then disconnect the brake pressure bleeder from the master cylinder reservoir bleeder adapter.
17. Remove the master cylinder reservoir bleeder adapter from the master cylinder reservoir.
18. Fill the brake master cylinder reservoir to the maximum-fill level with GM approved brake fluid from a clean, sealed brake fluid container.
19. Slowly press and release the brake pedal. Observe the brake pedal feel.
20. If the brake pedal feels spongy, perform the Bleeding the Complete Brake Hydraulic System procedure
21. Turn the ignition key ON, with the engine OFF. Check to see if the brake system warning lamp remains illuminated.
22. If the brake system warning lamp remains illuminated, refer to «Diagnostic Starting Point - Vehicle»(/cadillac/ats/i-2012-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__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»(/cadillac/ats/i-2012-2014/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»(/cadillac/ats/i-2012-2014/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»(/cadillac/ats/i-2012-2014/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»(/cadillac/ats/i-2012-2014/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»(/cadillac/ats/i-2012-2014/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 manufacturer's 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 manufacturer's 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»(/cadillac/ats/i-2012-2014/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»(/cadillac/ats/i-2012-2014/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»(/cadillac/ats/i-2012-2014/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)»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system) , «Hydraulic Brake System Bleeding (Pressure)»(/cadillac/ats/i-2012-2014/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»(/cadillac/ats/i-2012-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__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»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system) «Master Cylinder Replacement»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system) «Front Brake Hose Replacement (JE5)»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system) , «Front Brake Hose Replacement (J55)»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system) «Rear Brake Hose Replacement»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system) «Front Brake Caliper Replacement (JE5)»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#disc-brake-system) , «Front Brake Caliper Replacement (J55)»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#disc-brake-system) «Rear Brake Caliper Replacement»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#disc-brake-system) «Brake Pressure Modulator Valve Replacement»(/cadillac/ats/i-2012-2014/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»(/cadillac/ats/i-2012-2014/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»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system) . Replace the brake master cylinder reservoir cap diaphragm. «Front Brake Hose Replacement (JE5)»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system) , «Front Brake Hose Replacement (J55)»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system) «Rear Brake Hose Replacement»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system) «Front Brake Caliper Replacement (JE5)»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#disc-brake-system) , «Front Brake Caliper Replacement (J55)»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#disc-brake-system) «Rear Brake Caliper Replacement»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#disc-brake-system) «Brake Pressure Modulator Valve Replacement»(/cadillac/ats/i-2012-2014/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)»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system) , «Hydraulic Brake System Bleeding (Pressure)»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system) .

1. With the engine OFF, apply and release the brake pedal several times until the pedal becomes firm to deplete the power vacuum brake booster vacuum reserve.
2. Remove the left front end sheet metal diagonal brace. Refer to «Front End Sheet Metal Diagonal Brace Replacement - Left Side»(/cadillac/ats/i-2012-2014/remont/exteriorinterior-trim/#bolted-exterior-body-panels-and-closures) .
3. Disconnect the power brake booster vacuum sensor electrical connector.
4. Remove the power brake booster vacuum sensor (1) and hose assembly from the power vacuum brake booster and position aside.
5. Remove the master cylinder. Refer to «Master Cylinder Replacement»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system) .
6. Remove the brake pedal position sensor. Refer to «Brake Pedal Position Sensor Replacement»(/cadillac/ats/i-2012-2014/remont/exterior-lights/#lighting-system-repair-instructions__brake-pedal-position-sensor-replacement) .
7. Release the brake pedal (1) from the power vacuum brake booster pushrod by lifting the pedal upward.
8. Remove and discard the power brake booster pushrod retainer.
9. Remove the power vacuum brake booster nuts (1).
10. Remove the power vacuum brake booster (1).
11. Inspect the power vacuum brake booster gasket (2) for damage and replace, if necessary.

1. Install the power vacuum brake booster (1) and gasket (2).
2. Install the power vacuum brake booster nuts (1) and tighten to 25 (18 lb ft).
3. Install a new power brake booster pushrod retainer to the brake pedal arm.
4. Install the brake pedal (1) to the power brake booster pushrod.
5. Install the brake pedal position sensor. Refer to «Brake Pedal Position Sensor Replacement»(/cadillac/ats/i-2012-2014/remont/exterior-lights/#lighting-system-repair-instructions__brake-pedal-position-sensor-replacement) .
6. Install the master cylinder. Refer to «Master Cylinder Replacement»(/cadillac/ats/i-2012-2014/remont/mechanical-hydraulic/#hydraulic-brake-system) .
7. Install the power brake booster vacuum sensor (1) to the power vacuum brake booster.
8. Connect the power brake booster vacuum sensor electrical connector.
9. Install the left front end sheet metal diagonal brace. Refer to «Front End Sheet Metal Diagonal Brace Replacement - Left Side»(/cadillac/ats/i-2012-2014/remont/exteriorinterior-trim/#bolted-exterior-body-panels-and-closures) .

1. Apply the brake pedal several times until the pedal becomes firm to deplete the vacuum reserve in the brake booster.
2. Remove the intake manifold insulator. Refer to «Intake Manifold Insulator Replacement»(/cadillac/ats/i-2012-2014/remont/mechanical/#engine-mechanical-36l-lfx-repair-instructions-on-vehicle) .
3. Disconnect the power brake booster vacuum sensor electrical connector.
4. Remove the check valve (1) from the power brake booster.
5. Release the clamp and remove the power brake booster vacuum hose (1) from the vacuum port on the intake manifold.
6. Release the power brake booster vacuum hose quick connect (1) from the power brake booster pump.
7. Remove the power brake booster vacuum hose and check valve assembly from the vehicle.

1. Install the power brake booster vacuum hose and check valve assembly to the vehicle.
2. Install the power brake booster vacuum hose quick connect (1) to the power brake booster pump.
3. Release the clamp and install the power brake booster vacuum hose (1) to the vacuum port on the intake manifold.
4. Install the check valve (1) to the power brake booster.
5. Connect the power brake booster vacuum sensor electrical connector.
6. Install the intake manifold insulator. Refer to «Intake Manifold Insulator Replacement»(/cadillac/ats/i-2012-2014/remont/mechanical/#engine-mechanical-36l-lfx-repair-instructions-on-vehicle) .

1. Apply the brake pedal several times until the pedal becomes firm to deplete the vacuum reserve in the brake booster.
2. Remove the intake manifold cover. Refer to «Intake Manifold Cover Replacement»(/cadillac/ats/i-2012-2014/remont/mechanical/#engine-mechanical-20l-ltg-or-25l-lcv-repair-instructions-on-vehicle) .
3. Remove the outer fuel pump insulator. Refer to «Fuel Pump Insulator Replacement (Inner)»(/cadillac/ats/i-2012-2014/remont/testing-diagnostics/#engine-controlsfuel-20l-ltg-or-25l-lcv-repair-instructions) , «Fuel Pump Insulator Replacement (Outer)»(/cadillac/ats/i-2012-2014/remont/testing-diagnostics/#engine-controlsfuel-20l-ltg-or-25l-lcv-repair-instructions) .
4. Disconnect the power brake booster vacuum sensor electrical connector.
5. Remove the power brake booster vacuum sensor and hose (1) from the power brake booster.
6. Release the power brake booster vacuum hose quick connect (1) from the power brake booster vacuum pump.
7. Release the power brake booster vacuum hose from the clip (1).
8. Release the quick connect (1) and remove the power brake booster vacuum hose from the vacuum port on the intake manifold.
9. Disconnect the vacuum pipe (1) from the power brake booster vacuum hose.
10. Remove the power brake booster vacuum hose and check valve assembly from the vehicle.

1. Install the power brake booster vacuum hose and check valve assembly to the vehicle.
2. Connect the vacuum pipe (1) to the power brake booster vacuum hose.
3. Install the power brake booster vacuum hose to the vacuum port on the intake manifold and connect the quick connect (1).
4. Install the power brake booster vacuum hose to the clip (1).
5. Install the power brake booster vacuum hose quick connect (1) to the power brake booster vacuum pump.
6. Install the power brake booster vacuum sensor and hose (1) to the power brake booster.
7. Connect the power brake booster vacuum sensor electrical connector.
8. Install the outer fuel pump insulator. Refer to «Fuel Pump Insulator Replacement (Inner)»(/cadillac/ats/i-2012-2014/remont/testing-diagnostics/#engine-controlsfuel-20l-ltg-or-25l-lcv-repair-instructions) , «Fuel Pump Insulator Replacement (Outer)»(/cadillac/ats/i-2012-2014/remont/testing-diagnostics/#engine-controlsfuel-20l-ltg-or-25l-lcv-repair-instructions) .
9. Install the intake manifold cover. Refer to «Intake Manifold Cover Replacement»(/cadillac/ats/i-2012-2014/remont/mechanical/#engine-mechanical-20l-ltg-or-25l-lcv-repair-instructions-on-vehicle) .

1. Remove the air cleaner outlet duct. Refer to «Air Cleaner Outlet Duct Replacement»(/cadillac/ats/i-2012-2014/remont/testing-diagnostics/#engine-controlsfuel-36l-lfx-repair-instructions) .
2. Release the power brake booster pump hose quick connect (1).
3. Disconnect the power brake booster pump hose from the auxiliary pump.
4. Unclip the booster pump hose retainer from the booster pump bracket, reposition the hose.
5. Disconnect the power brake booster pump electrical connector.
6. Remove the power brake booster pump bracket M6 bolt (1).
7. Remove the power brake booster pump bracket M12 bolt (2).
8. Remove the power brake booster pump from the engine.
9. Remove the power brake booster pump bolts (1) and nuts (2).
10. Release the power brake booster pump electrical harness connector retainer from the bracket.
11. Remove the power brake booster pump bracket (1).
12. Remove the power brake booster pump insulator sleeves (1).
13. Remove the power brake booster pump insulators (2).

1. Assemble the power brake booster pump sleeves (1) to the insulators (2).
2. Install the power brake booster pump insulators.
3. Install the power brake booster pump bracket (1).
4. Install the power brake booster pump bolts (1) and nuts (2) and tighten to 22 (16 lb ft).
5. Install the power brake booster pump electrical harness connector retainer to the bracket.
6. Position the power brake booster pump to the engine.
7. Loosely install the power brake booster pump bracket M6 bolt (1).
8. Loosely install the power brake booster pump bracket M12 bolt (2).
9. Tighten the power brake booster pump bracket M6 bolt to 10 (89 lb in).
10. Tighten the power brake booster pump bracket M12 bolt to 70 (52 lb ft).
11. Install the power brake booster pump hose.
12. Connect the power brake booster pump hose quick connect (1).
13. Connect the power brake booster pump electrical connector.
14. Install the air cleaner outlet duct. Refer to «Air Cleaner Outlet Duct Replacement»(/cadillac/ats/i-2012-2014/remont/testing-diagnostics/#engine-controlsfuel-36l-lfx-repair-instructions) .

1. Apply the brake pedal several times until the pedal becomes firm to deplete the vacuum reserve in the brake booster.
2. Remove the intake manifold cover. Refer to «Intake Manifold Cover Replacement»(/cadillac/ats/i-2012-2014/remont/mechanical/#engine-mechanical-20l-ltg-or-25l-lcv-repair-instructions-on-vehicle) .
3. Remove the outer fuel pump insulator. Refer to «Fuel Pump Insulator Replacement (Outer)»(/cadillac/ats/i-2012-2014/remont/testing-diagnostics/#engine-controlsfuel-20l-ltg-or-25l-lcv-repair-instructions) .
4. Release the power brake booster vacuum hose quick connect (1) from the power brake booster vacuum pump.
5. Remove the upper bolts (1) from the power brake booster pump.
6. Remove the lower bolt (2) from the power brake booster pump and remove the pump.
7. Remove the power brake booster pump gasket (1).

1. Install the power brake booster pump gasket (1).
2. Install the power brake booster pump to the engine.
3. Install the upper bolts (1) to the power brake booster pump and tighten to 10 (89 lb in).
4. Install the lower bolt (2) to the power brake booster pump and tighten to 10 (89 lb in).
5. Install the power brake booster vacuum hose quick connect (1) to the power brake booster vacuum pump.
6. Install the outer fuel pump insulator. Refer to «Fuel Pump Insulator Replacement (Outer)»(/cadillac/ats/i-2012-2014/remont/testing-diagnostics/#engine-controlsfuel-20l-ltg-or-25l-lcv-repair-instructions) .
7. Install the intake manifold cover. Refer to «Intake Manifold Cover Replacement»(/cadillac/ats/i-2012-2014/remont/mechanical/#engine-mechanical-20l-ltg-or-25l-lcv-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.

At rest, source vacuum is applied to both sides of each of the diaphragms in the dual booster. Return springs maintain the booster in a rest position.

When brake system force is applied, vacuum to the rear of the diaphragms is cut off, and air at atmospheric pressure is admitted in its place. The vacuum acts to pull the diaphragms 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.

Scheme 6

The Brake Booster Vacuum Assist system consists of the following

The pump can be switched on and off by the Electronic Brake Control Module based on the required vacuum. Pressure variations during braking can be measured, and the pump can be activated to generate additional vacuum if required to increase the braking force.

The pump runs for the first 5 seconds after engine running to perform a self test. Engine running, the pump may run another 30 seconds and then turns off, due to the timer relay. The pump has a maximum run time of 180 seconds per ignition cycle with engine running, when it reaches the maximum run time the pump shuts down to cool off and will not allow the pump to run again until the next engine run cycle.

Scheme 7

The instrument cluster turns the brake warning indicator ON when the following occurs

1. The instrument cluster performs the bulb check. The brake warning indicator illuminates for 5 s.
2. When the electronic brake control module (EBCM) detects low brake fluid level it sets DTC C0267 and sends a serial data message to the instrument cluster, which will illuminate the red brake indicator.

Driver Information Center Messages

When the electronic brake control module (EBCM) detects low brake fluid level it sets DTC C0267 and sends a serial data message to the driver information center , which will display Brake Fluid Low message.

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 CH 28662 J 28662 Brake Pedal Effort Gauge CH 29532-A J 29532-B Pressure Brake Bleeder CH 44894-A J 44894-A Brake Bleeder Adapter CH 45405 J 45405 Brake Pipe Flaring Kit

Scheme 8

Scheme 9

Scheme 10

Scheme 11

See also:
• Diagnostic System Check - Vehicle
• Strategy Based Diagnosis
• Diagnostic Procedure Instructions
• Symptom Byte List
• COMPONENT CONNECTOR END VIEWS - INDEX
• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs
• Control Module References
• Diagnostic Repair Verification
• ABS Description and Operation
• Checking Aftermarket Accessories
• Diagnostic Starting Point - Vehicle
• Park Brake System Diagnosis
• Front Disc Brake Pads Replacement (JE5)
• Front Disc Brake Pads Replacement (J55)
• Front Disc Brake Mounting and Hardware Inspection
• Rear Disc Brake Mounting and Hardware Inspection
• Front Brake Caliper Hardware Replacement (J55)
• Front Brake Caliper Overhaul (JE5)
• Front Brake Caliper Overhaul (J55)
• Rear Brake Caliper Overhaul
• Front Wheel Drive Shaft Replacement - Left Side
• Front Wheel Drive Shaft Replacement - Right Side
• Rear Wheel Drive Shaft Replacement
• Brake Rotor Thickness Measurement
• Brake Rotor Thickness Variation Measurement
• Brake Rotor Surface and Wear Inspection
• Brake Rotor Refinishing
• Front Brake Rotor Replacement (JE5)
• Front Brake Rotor Replacement (J55)
• Rear Brake Rotor Replacement
• Brake Rotor Assembled Lateral Runout Measurement
• Brake Rotor Assembled Lateral Runout Correction
• Hydraulic Clutch System Bleeding
• Brake Pressure Modulator Valve Replacement
• Clutch Master Cylinder 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
• Fastener Caution
• Instrument Panel Tie Bar Replacement
• Brake Pedal Position Sensor Replacement
• Plenum Front Panel Replacement
• Fuel Pump Insulator Replacement (Outer)
• Intake Manifold Insulator Replacement
• Heater Inlet Hose Replacement (LFX)
• Upper Intermediate Steering Shaft Replacement (RWD)
• Brake Dust Warning
• Fluid and Lubricant Recommendations
• Intake Manifold Cover Replacement
• Air Cleaner Outlet Duct Replacement
• DTC C0267
• Brake Fluid Loss
• Brake Assist System Diagnosis
• Brake Pulsation
• Brake System Noise
• Brake Pedal Excessive Travel
• Brake Pedal Excessive Effort
• Brakes Drag
• Brake System Slow Release
• Brake Pedal Travel Measurement and Inspection
• Brake Pedal Pushrod Inspection
• Brake Pipe Replacement
• Master Cylinder Reservoir Filling
• Hydraulic Brake Component Operation Visual Inspection
• Brake Pipe and Hose Inspection
• Brake System Internal Leak Test
• Brake System Vacuum Source Test
• Symptoms - Hydraulic Brakes
• Special Tools
• Brake System Specifications
• Brake System External Leak Inspection
• Master Cylinder Bench Bleeding
• Fastener Tightening Specifications