mm28 Anti Lock Braking Systems ABS for Trucks, Tractors, and Buses C Version

1 Introduction

Components The Electronic Control Unit (ECU) is the brain of the system. It receives information from the sensors and sends signals to the ABS valves. The ECU may be mounted in the cab or on the frame of the vehicle. As illustrated, cab- and frame-mounted ECUs use a different style connector. Figure 1.1.

A sensor is installed so that its end is against the tooth wheel. The sensor continuously sends wheel speed information to the ECU. On a four-channel ABS, two sensors are installed on the steering axle and two additional sensors are mounted on one drive axle. The sensors on the steering axle are installed in the steering knuckle. The sensors on the drive axle are mounted in a block attached to the axle housing. Figure 1.3.

Figure 1.1

Figure 1.3

CAB-MOUNTED

FRAME-MOUNTED

1000406a

Figure 1.3

1000404a

The sensor clip holds the sensor in place at the tooth wheel. Figure 1.4.

Figure 1.1

NOTE: Do not open the ECU. Opening the ECU to gain access to the internal components will void the warranty.

Figure 1.4

The tooth wheel is mounted on the hub of each monitored wheel. Figure 1.2.

Figure 1.2

1000407a

Figure 1.4

An ABS modulator valve controls air pressure to each affected brake during ABS function. Figure 1.5.

1000405a

Figure 1.2

2

WABCO Maintenance Manual MM-28 (Revised 03.2020)