Introductions of semi-trailers ABS system (Part 5)

Introduction of semi-trailers ABS system (Part 5)

- How to judge whether the ABS system is working normally

1. Static methods

When the vehicle's ignition switch is turned on, the ABS system will immediately conduct a static system test. The ABS warning lamp on the instrument panel will be turned on and then extinguished within three seconds, and then the cyclic running sound of the solenoid regulating valve will be heard. Because the wheel speed sensor does not generate the wheel speed signal during the static test, even if the system pass through the static test at this time, the normal operation of the sensor cannot be guaranteed. It is also necessary to pay attention to the results of the subsequent dynamic test.

For example:

Steps to check whether the ABS system works normally (4S/4M basic model):

(1) Press the brake pedal;

(2) Turn on the ignition switch;

(3) Observe the instrument panel: the ABS warning lamp is on and then extinguished within three seconds;

(4) Then hear the running sound of the solenoid regulating valve circulating for 10 times. (The first six times are exhaust operation, and the sequence is: left front - left rear - right rear - right front - left front & right rear - right front & left rear; the last four times are pressure maintaining operation, and the sequence is: left front - left rear - right rear - right front). If the exhaust sound is not 6 times or the sequence is wrong, check the wiring of the solenoid valve and the corresponding harness.

2. Dynamic methods

Dynamic method 1:  Check warning lamp when vehicle moves.

When the vehicle moves, the ECU (Electronic Control Unit) receives and detects and judges the voltage signal of the wheel speed sensor. If the vehicle speed is more than 7KM/H, the warning lamp is not on, indicating that the sensor can pass the dynamic detection and work normally; if the vehicle speed is more than 7KM/H, the warning lamp flashes, indicating that the ABS system is faulty.

Dynamic method 2:  Real-time monitoring.

As long as the ABS system is powered on, whether the vehicle is stationary or in the whole process of driving, the system fault monitoring is always working. It monitors whether the circuit functions of each component of the system are normal in real time. During the whole process of vehicle driving, when there is a fault in the system, the warning lamp will flash regularly. The flashing code can be read out through its flashing status, and then the fault type and fault location can be determined by comparing the flashing code table.

Dynamic method 3:  Visual judgment by implementing emergency braking.

Emergency braking: select a wide and flat road, and confirm that the road is safe. When the vehicle speed is more than 40KM/H, implement emergency braking, and all wheels shall not be locked. Observe the brake trace. If there is no brake drag trace or the brake drag trace is regular and intermittent, it indicates that the ABS system works; on the contrary, it indicates that the ABS system function does not work.

Compiled by  WONDEE Autoparts

2022-6-29