ABS Description and Operation: Notes

This vehicle is equipped with the DBC7.2 antilock braking system.

The vehicle is equipped with the following systems:

• Antilock Brake System (ABS)
• Dynamic Rear Proportioning (DRP)
• Traction Control System (TCS) (w/NW7)

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 - Supplies battery positive voltage to the solenoid valve relay and pump motor. The system relay is energized when the ignition is ON when no ABS DTCs are present that disable the ABS system.
  • Solenoid Valve Relay - Supplies battery positive voltage to the solenoid valves. The solenoid Valve Relay is energized when the EBCM enters an ABS braking event.
  • 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 solenoid valves and pump motor that are controlled by the EBCM to isolate or release brake pressure to individual wheels.

  The BPMV contains the following components:

  • Pump Motor
  • Inlet Valves (one per wheel)
  • Outlet Valves (one per wheel)
• Wheel Speed Sensors (WSS) - EBCM sends a 12-volt reference voltage signal to each wheel speed sensor. As the wheel spins, the wheel speed sensor produces a DC digital signal. The wheel speed sensor increases the signal frequency as the wheel speed increases, but does not increase the signal amplitude. The wheel speed sensors are replaceable only as part of the wheel hub and bearing assemblies.
• Traction Control Switch (w/NW7) - The TCS is manually disabled or enabled using the traction control switch.
• Brake Pedal Position Sensor (BPP) - The EBCM uses the BPP as an indication that the brake pedal is applied.