Guide to Electronically Controlled Air Suspension for Trucks

Electronically Controlled Air Suspension

With the development of the transportation industry, the configuration of trucks is constantly updated and the functions are more comprehensive. In the use of suspension systems, air suspension and mechanical suspension have been applied to vehicles such as semi-trailers and buses. In recent years, high-end suspension configurations have also appeared on trucks-electronically controlled air suspension systems (ECAS).

What is Truck Electronically Controlled Air Suspension System?

Electronically Controlled Air Suspension, ECAS for short. It is a new type of air suspension. Primarily used in trucks and heavy commercial vehicles. It is composed of electronic control unit (ECU), combined solenoid valve, height sensor, control switch, air pressure transmission pipeline and other parts. ECAS monitors and controls the air pressure of the truck suspension system in real time to achieve precise adjustment of parameters such as suspension height, stiffness and damping.

Electronically Controlled Air Suspension can detect the state of the vehicle during operation through sensors. Such as speed, load, acceleration, braking force, etc. Then the air pressure in the airbag is adjusted by the ECU, thereby changing the suspension height and hardness of the vehicle. This allows the truck to maintain a stable suspension height in different road conditions.

Electronically Controlled Air Suspension

The Operating Principle of ECAS

The electronically controlled air suspension monitors the distance between the frame and the axle in real time through a height sensor installed on the frame, and is connected to the axle through a swing link. When the height of the truck body and the bridge changes, the height sensor sends a signal to the ECU. The ECU compares the current height with its stored set height, and then sends a control signal to the solenoid valve to inflate or exhaust the airbag, thereby realizing constant control of the truck body height.

This effectively reduces driveline vibration and wear by controlling the height of the truck body at an optimum ride level. And there is no continuous air consumption during driving, and it can also improve fuel economy to a certain extent.

Electronically Controlled Air Suspension

Advantages of Electronically Controlled Air Suspension

  1. The main advantage of ECAS: it can quickly and accurately reach the required control height. Because the solenoid valve adopts a large-section air inlet and outlet. This can result in excess air still being inflated into the airbag and resulting in subsequent altitudes that are higher than the desired standard altitude. However, ECAS can control the solenoid valve through the pulse current, so that the solenoid valve can interrupt the flow of gas in a short time, so as to complete the fast and accurate height adjustment.
  2. Keep the chassis height constant under no load and heavy load. This can ensure that the docking between the truck and the cargo bed is always maintained during the loading and unloading of the truck, improving the efficiency of loading and unloading operations.
  3. When a truck equipped with a lifting axle starts, it can control the axle load distribution between the drive axle and the lifting axle (traction assist control). This can effectively prevent the drive wheels from slipping when the vehicle starts off on bad roads.
  4. Use the remote control to realize the frame lifting more conveniently. It is convenient for the driver to pick up and hang up. The driver can also set the memory altitude. Under specific conditions of use, the driver can easily recall the memory altitude, avoiding repeated adjustments.
Electronically Controlled Air Suspension

Electronically Controlled Air Suspension Faults and Troubleshooting Methods

Although the Electronically Controlled Air Suspension system can bring a lot of convenience to the driver, it is inevitable to encounter some failures during use. Below we have sorted out the more common faults and troubleshooting methods of the electronically controlled air suspension system:

Symptom 1: The height indicator light (yellow) is always on

Troubleshooting: Check whether the height of the truck is at the normal height position. If the air pressure of the vehicle is sufficient, you can press the button to restore the normal height.

Symptom 2: Altitude indicator flashes

Troubleshooting: You can check the air storage tank that inflates the airbag to see if the pressure is less than 0.6 MPa, and check the air leakage of the air circuit at the same time.

Symptom 3: The chassis frame is tilted

Troubleshooting: Check whether the connection of all height sensors is firm; recalibrate the height sensor if necessary.

Symptom 4: The airbag will slowly descend when working at full load

Troubleshooting: Check the air bag for leaks and the trachea for leaks.

Symptom 5: The lifting axle cannot be lifted during driving

Troubleshooting: Check whether the power supply of all pressure sensors is normal and whether the line connection is firm.

Symptom 6: The lift operation of the airbag is slow

Troubleshooting: Check whether the pressure of the air storage tank of the air suspension is normal, and check whether the pipeline is bent.

Symptom 7: After the vehicle is turned off for a period of time, the body appears skewed

Troubleshooting: Check the air tightness of the gas pipeline between the ECAS solenoid valve and each airbag. It is recommended to lower the height of the truck before turning off the engine.


There are more and more high-end configurations such as electronically controlled air suspension systems applied to trucks, which have indeed brought a lot of convenience and comfort to the truck. It is worth reminding that in normal truck maintenance, we should pay more attention to these accessories, repair and maintain them in time.

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