ABS Description and Operation: Notes
WARNING: This page is about a different car, the 2007 Hummer H2. However, it is still accessible from the selected car via links, so may be relevant.
| Callout | Component Name |
|---|---|
| 1 | Master Cylinder |
| 2 | Master Cylinder Reservoir |
| 3 | Pump |
| 4 | Rear Master Cylinder Isolation Valve |
| 5 | Rear Prime Valve |
| 6 | Brake Pressure Modulator Valve (BPMV) |
| 7 | Damper |
| 8 | Right Rear Inlet Valve |
| 9 | Accumulator |
| 10 | Right Rear Brake |
| 11 | Right Rear Outlet Valve |
| 12 | Left Rear Outlet Valve |
| 13 | Left Rear Brake |
| 14 | Left Rear Inlet Valve |
| 15 | Left Front Inlet Valve |
| 16 | Left Front Brake |
| 17 | Left Front Outlet Valve |
| 18 | Right Front Brake |
| 19 | Right Front Outlet Valve |
| 20 | Accumulator |
| 21 | Right Front Inlet Valve |
| 22 | Damper |
| 23 | Front Master Cylinder Isolation Valve |
| 24 | Front Prime Valve |
This vehicle is equipped with the Bosch 5.3 antilock braking system.
The vehicle is equipped with the following braking systems:
- Antilock Brake System (ABS)
- Dynamic Rear Proportioning (DRP)
- Traction Control System TC2 (w/NW9)
The following components are involved in the operation of the above systems:
- Electronic Brake Control Module (EBCM) - The EBCM controls the system functions and detects failures.
The EBCM contains the following components:
- System Relay - The system relay is energized when the ignition is ON and no ABS DTCs are present. It supplies battery positive voltage to the solenoid valves and pump motor.
- Vent Tube - The vent tube, located in the EBCM connector, is an opening to the internal cavity of the EBCM. It allows ventilation of the EBCM internals.
- Brake Pressure Modulator Valve (BPMV) - The BPMV contains the hydraulic valves and pump motor that are controlled electrically by the EBCM. The vehicle is equipped with traction control The BPMV uses a 4 circuit configuration with a front/rear split. The BPMV directs fluid from the reservoir of the master cylinder to the front wheels and fluid from the other reservoir to the rear wheels. The circuits are hydraulically isolated so that a leak or malfunction in one circuit will allow continued braking ability on the other.IMPORTANT: There is a rubber isolator located under the BPMV and on the mounting studs. The rubber isolators protect the BPMV and the EBCM from vehicle vibrations.
The BPMV contains the following components:
- Pump Motor
- Inlet Valves (one per wheel)
- Outlet Valves (one per wheel)
- Master Cylinder Isolation Valves (w/NW9) (one per drive wheel)
- Prime Valves (w/NW9) (one per drive wheel)
- Longitudinal accelerometer (W/NW9) - The longitudinal accelerometer is used to determine straight-line acceleration. This information is used for Traction Control in the AWD, 4WD applications.
- Stoplamp Switch - The EBCM uses the stoplamp switch as an indication that the brake pedal is applied.
- Traction Control Switch, TC2 (w/NW9) - The TC2 is manually operated to enabled loose surface or road mode.
- Wheel Speed Sensors (WSS) - As the wheel spins, the wheel speed sensor produces an AC signal. The EBCM uses this AC signal to calculate wheel speed. Any imperfections in the toothed ring, such as a missing or damaged tooth, can cause an inaccurate WSS signal.