Common Failures And Solutions Of Semi Trailer ABS Braking System

Common Failures And Solutions Of Semi Trailer ABS Braking System

The safety of semi-trailers in the driving process is very important. The application of ABS in the braking of vehicles is of great significance to improving the safety and stability of vehicles in the process of driving. Today I will share with you some common failure cases and maintenance precautions of ABS.

1.The composition of the semi trailer brake system

The semi-trailer ABS system specifically refers to the anti-lock braking system, which is an additional device on the original car braking system to control the stability of the car body during the braking process. The ABS system is mainly composed of three parts: wheel sensors, controllers and regulators. After braking, the ABS system mainly achieves the vehicle’s stable control goal by controlling the slip rate and wheel speed of the wheels.

The semi trailer brake is generally an air brake, and the air source comes from the tractor. There are three main parts: emergency relay valve, trailer ABS and brake air chamber.

In the absence of air leakage due to improper sealing, most of the failures come from these three large pieces. Of course, the problem is all-round. All parts related to the air brake will have varying degrees of impact, so the installation should not be taken lightly.

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2.Installation requirements of the gas circuit

In addition to the three large pieces, the installation of the gas circuit is very basic, but if it is not done properly, the effect of the vehicle will be unsatisfactory. The gas circuit connection must not be lengthy and unnecessary entanglement. A qualified gas circuit is generally simple and clear.

When installing the gear ring, in addition to cleaning the dirt on the installed reserved groove, there are also several points to note:

1. When the ring gear is installed, it should be fully heated to about 180-200 degrees, and the temperature should be kept for 5-10 minutes, and then the ring gear should be assembled.

2. The ring gear is heated to the point where it can be directly inserted into the hub slot and can rotate optimally. This can ensure that the ring gear is directly installed in place, without the need to use external force to correct the position of the ring gear.

3. It is forbidden to impact the gear ring with metal objects to avoid damage to the gear ring and affect the accuracy of the sensor signal.

I would also like to remind all car owners here that when installing ABS on their own, do not use electric welding to ream on the dust-proof baffle. It is easy to cause irregular rounds in the reaming, and it is easy to damage the wire. After all the sensor brackets are installed, the sensor is installed very neatly and beautifully.

In addition, the internal diameter of the air pipe and the joint must meet the standard, if not, the braking effect will be poor. The air circuit completed as required not only has superior braking performance, lower failure rate, but also facilitates future maintenance and after-sales, which will serve multiple purposes.

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3.ABS inspection

1. Check whether the connection status of various devices and firmware in the ABS system is tight, especially the installation of connectors and cables, and analyze the interference coupling effect of related components and other components. The devices that cause interference should be improved and improved. The upgrade promotes the normal operation of the ABS system. In addition, it is necessary to place the ABS switch in the “on” position, turn on the power of the car, and check whether the ABS warning light is displayed normally.

2. Keep the semi-trailer in the running state, the vehicle speed is 10 kilometers per hour, at this time the ABS warning light is in the off state, it can be determined that the semi-trailer’s ABS system is operating normally. If the ABS warning light is in a flashing state, it means that the ABS system is not operating normally and its stable working conditions are affected. At this time, the driver should continue to observe the flashing frequency of the warning light. Different frequencies correspond to different fault codes, which need to be based on the actual situation. , Determine the type of failure, and take targeted improvement measures. For example, if the ABS warning light flashes alternately with an interval of 1 second, the fault code is 1.1. The specific meaning is that the exhaust solenoid of the left front regulator has a fault. The troubleshooting method is maintenance or replacement.

4.Common faults and solutions

4-1Common failure phenomenon one

1: The air pressure has been lower than 0.7MPa for a long time or the trailer has obvious drag brakes during the driving process. ‍‍‍‍The processing method is as follows:

a. Replace the front of the car and troubleshoot the tractor.

b. Check the source of air leakage by applying soapy water, and eliminate “air leakage at the handshake connection”, “pipe joint leakage”, “brake chamber air leakage”, “emergency relay valve air leakage”, and “trailer ABS” Possible failures such as “valve leaks”.

If it exists, you need to check whether the valve body enters water or can see obvious rust. This phenomenon indicates that the trailer air pipeline is not well filtered and dried, and the valve body may need to be replaced.

4-2Common fault phenomenon two

The trailer cannot be started after being parked, and it has been locked. The processing method is as follows:

A. First, unplug the ABS spiral wire to see if it can start normally to eliminate circuit problems.
B. Put the tractor in the inflating state, unplug the air pipe of the manual valve, and check whether the air pressure of the air outlet is normal (the air pressure should be very large in the inflated state).
C. Check whether the parking brake is in the released state.
D. If there is no problem with the gas circuit inspection, finally check the axle content for mechanical failure.

In all braking states of the trailer braking system, the safety design completely keeps the air supply pipeline unblocked. Both the foot brake of the tractor and the parking brake measures are effective by supplying air to the control pipeline.

5.Tips for daily maintenance of trailer braking system

1. After the new car is received, check whether the ABS is working properly, and make sure that it is working properly before checking the car to the home. The working status of the ABS is still checked before the car is reviewed every year, and the car is reviewed after it is working properly.

2. Regularly replace and clean the dryer and filter of the tractor to prevent the dirt in the pipeline from damaging the ABS.

3. Every 15 days in winter (monthly in summer), clean the accumulated water in the main vehicle and trailer air tank, especially in winter, otherwise the valve cannot be operated due to the freezing of the water in the pipeline, which may cause a safety accident or impact Use performance.

4. Every time the axle is maintained or the brake shoe is replaced, the dust or oil on the surface of the sensor and gear ring should be removed in time, and the front part of the gear ring or sensor should be kept clean.

5. Every time the axle is maintained or the brake shoe is replaced, after removing the dust or oil on the surface of the sensor, push the sensor to the end in the direction of the ring gear to ensure that the sensor can touch the ring gear after the wheel is installed. When the wheel is moving, because the bush is elastic, the sensor will automatically retreat, so as to maintain the best working gap (less than 0.75mm).

6. When replacing or maintaining the sensor, pay attention to whether the clamping force between the sensor and the elastic bushing is appropriate (the clamping force should be 120~200N). If it is too small, the elastic bushing must be replaced.

7. Check the ABS wiring harness and air circuit every week for wear, interference, peeling and aging, electric leakage and air leakage.

8. Check and clean up the dust, rust and other dirt inside each plug connector every month.

9. Check every month whether the ABS regulators and ECU fixing bolts and nuts are loose and tighten them in time.


ABS only works when emergency braking causes the wheels to lock up. In layman’s terms, ABS acts like a driver’s “spot braking” quickly and frequently, but the driver’s “spot braking” frequency cannot be compared with ABS in any way. ABS can change 3 to 5 times per second. . When a vehicle equipped with ABS encounters an emergency braking in a dangerous situation, the clutch should be stepped down quickly, and then the foot should be slammed to brake, while the steering wheel can still be turned to make the vehicle avoid obstacles.

If the ABS light is on while the vehicle is running, it means that the ABS system is malfunctioning, but the conventional braking is still working and the vehicle can still be driven safely. Now more and more customers are restructuring the trailer air circuit by themselves. Due to improper restructuring, the original braking system has been destroyed and many safety and quality accidents have been caused.

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