TM 9-2320-302-20
0013 00-1
ANTI-LOCK BRAKE SYSTEM (ABS) TROUBLESHOOTING AND TESTING
0013 00
INTRODUCTION
This work package contains information on troubleshooting and testing the Anti-lock Brake System (ABS) using blink
code diagnostics and Prolink. The ABS is an electronic system that monitors and controls braking only during emergency situ-
ations. The ABS controls the braking of each wheel separately, which prevents wheel locking, maintains steerability, and
reduces stopping distance. The ABS has two diagonal circuits. Each circuit connects the front wheel of one side of the vehicle
to the rear wheels of the opposite side. In case of a system fault, only half of the ABS stops working. Control of that half is
returned to the standard braking system. The ABS uses a tone ring and sensor on the hub of each monitored wheel. The sensor
sends wheel speed information to the Electronic Control Unit (ECU). The ECU signals the modulator valve for that wheel to
increase, reduce or maintain pressure in the brake chamber (Figure 1).
PRETEST INSPECTION
Prior to performing vehicle test, ensure that daily Preventive Maintenance Checks and Inspections (PMCS) has been
performed.
A.
Air Lines
B.
Electrical Lines
1.
Cab-mounted ECU
3.
ABS Modulator Valves
5.
ABS Modulator Valves
2.
Wheel Speed Sensors
4.
Relay Valve
6.
Wheel Speed Sensor
Figure 1. Location of ABS Components.
GENERAL INFORMATION
1.
Rockwell WABCO ABS D Version is an electronic system that monitors and controls wheel speed during braking. The
system works with standard air brake systems. ABS monitors wheel speeds at all times and controls braking during
wheel lock situations. The system improves vehicle stability and control by reducing wheel lock during braking.
