Air Suspension Repair - Traction Control and ABS

We offer repair services for the air suspension of the car.

If you have problems with ABS or with ETS traction control system, then contact us, we will quickly and accurately diagnose and repair these systems for your car.

The air suspension is designed to support the body of the car at the same height. It is used in conjunction with adjustable shock absorbers, with the car's ground clearance adjusted as you need.

The air suspension device is a complex mechanism consisting of many reliable and durable elements, including a compressor, air tanks, a receiver, a distribution air main and a control system. Nowadays almost each premium car and off-road vehicle has an air suspension in their designs.

What is the repair of the pneumatic suspension?

Carrying out of diagnostics, repair of systems and body calibration

For many years now we have been repairing and repairing pneumatic suspension of any degree and complexity. During this time, a tremendous experience has been gained, which together with excellent modern equipment allows us to solve the set tasks quickly and qualitatively

Pneumatic suspension repair. What are the signs of a malfunction?

If the car squats during idle time, then the air suspension is faulty and it is necessary to urgently contact the specialists.The presence of a sound that resembles a bounce, when the compressor is running or an increase in time to create the necessary pressure in the system, is also indicative of a malfunction.

There are many factors that indicate the malfunction of the air suspension. But in order to accurately determine what went wrong, you need the help of professionals. High-precision equipment of specialized service centers and vast experience in eliminating breakages of different levels of complexity will help to identify the breakdown and promptly eliminate it.

Among the main signs of a malfunction of the air suspension some should be underlined:

  • incorrect operation of the pressure sensor of the receiver, air walkways, wiring, pneumatic cylinder;
  • damage or complete wear of the compressor valve block, airbags, piston group;
  • depressurization of pneumatic walls.


Anti Blocking System (ABS)


ABS is an active safety system that prevents the wheels from locking when braking, which keeps the car running in critical situations. ABS is not a system designed to reduce the length of the braking distance, but it allows to achieve optimal braking performance in various conditions of the road surface.

ABS on passenger cars

ABS has been manufactured since 1976 and was first installed on a 350SEL vehicle (type 116). In 1985, it was combined with ASR. In 1991 on type 140 there was a main brake cylinder with an interchangeable distribution of braking force between the front and rear contour. Serially ABS is installed on many types of cars since the 90s.
In 1995 with the advent of type 202 ABS has undergone another modernization. ABS works by releasing locked wheels, while the braking force on the front wheels is adjusted separately, and on the rear wheels together (3-channel ABS).
ABS is activated when the speed is increased to 8 km/h and remains active up to a speed of 3 km/h.
ABS works with a battery voltage of 10.7 to 18 volts.

Operating principle

During braking, the driver, pressing the brake pedal, creates pressure in the braking system, i.e. on each of the wheels, braking them.

The speed sensors for the front wheels and the rear axle report the current wheel speed to the electronic control unit ABS N47-7. The control unit compares the received signals and on their basis calculates the average theoretical speed of each wheel.

Comparing the current speeds of the front wheels separately and the rear axle with an average theoretical value, the control unit determines which of the wheels are locked and which ones are scrolled. If the locked wheels are detected, the ABS is activated.

First, the pressure in the brake system, created by the driver when the brake pedal is pressed, is maintained constant (preventing further increase). If any of the wheels remain in the locked state, the ABS resets the brake fluid pressure (by pumping it with a pump) to the locked / locked wheels.

The wheel on which the pressure was released starts scrolling with increasing speed. At this point, the pressure release stops. If the wheel speed exceeds a certain value, the control unit again applies pressure to the corresponding brake mechanism.

So the braking process consists of three phases:

  • Creation of pressure in the braking system on all wheels (with pressing the brake pedal by the driver)
  • Maintaining the driver-created pressure (by ABS)
  • Reset of pressure on the blocked wheel ( by ABS)

This cycle is repeated at a high frequency until the car stops completely or until the pedal is released. When the ABS is used, the driver feels a vibration on the brake pedal, which is associated with a cyclic pressure change in the braking system.

Comment! Braking force on front wheels is regulated separately, in the rear - together.

ABS Anti-lock Braking System (Components)

Electrical components

  • ABS control unit
  • wheel speed sensors
  • brake signal sensor
  • overvoltage relay
  • ABS warning lamp
  • pump-out relay
  • pump

Hydraulic components

  • brake master cylinder
  • hydraulic control unit
  • return pump in hydraulic unit
  • wheel brakes

* When the ABS is working, the vibration on the brake pedal is felt, which is normal.

* Bleeding the brakes on a car with ABS is the same as without it.

* Reading of faults in the ABS system is possible with the help of specialized equipment.

ETS traction control system


The electronic traction control system ETS is an automatic system to prevent the driving wheels from slipping during travel, acceleration, while moving straight and in turns. It serves to achieve the most optimal acceleration for a different state of the road surface and, at the same time, stabilize the car on the road.

The system works by braking one or both sliding drive wheels.

In the ETS hydraulic and electronic units, all ABS functions and ETS functions are combined.

ETS has been manufactured since 1994 and replaces the automatic blocking system of the ASD Differential, which was discontinued in 1997.

The ETS system is installed in particular for Mercedes cars of types 129 and 140 with 6-cylinder engines and type 210 with 4- and 6-cylinder series, for type 202 with 4-, 5- and 6-cylinder engines as additional equipment.

The M-class cars are equipped with a 4-ETS system, which affects all 4 wheels, which replaces the locking of the three differentials - interaxle and two inter-wheel.

When driving or starting, the ETS control unit N47 / 2 reads the speed signals from each of the front and rear axle wheels and calculates theoretical speed of the car. Depending on the speed of the wheels, the ETS can operate in ABS mode and, in fact, ETS.

Working in ABS mode

The braking mode with ABS does not differ from that considered in the ABS chapter. Just as in ABS, the front wheels are affected individually, the rear wheels are driven together, despite the presence of speed sensors on both rear wheels.


Working in ETS mode

One-wheel slippage

If the ETS recognizes the slippage of one driving wheel, it turns on. During this, the brake fluid is pressurized and the wheel braked until both driving wheels have the same speed. In this case, through the differential, the torque is transferred to another wheel, which, due to the increased torque, can also start to slip.

As soon as the ETS detects the spin of the second wheel, the braking effect on the first one will stop. The condition for including ETS in work is the difference between

the speed of rotation of the rear wheels > 4 km/h. The system ceases to operate when the speed difference drops to 2 km/h. This ETS mode is possible at speeds from 0 to 40 km/h, but at the beginning of the movement and acceleration in the mode of kickdown or full gas, the ETS operation is possible up to 80 km/h.

Two-Wheel Slippage

When the two drive wheels slip, a certain brake fluid pressure is created on them and the wheels brake to prevent the car from drifting. The ETS comes into effect if the speed of the rear wheels exceeds the front speed by 2.8 km/h and the front wheel speed difference > 1 km/h (motion recognition in cornering). The maximum braking time of both wheels is 2 seconds. Even if the conditions require more. This function operates in a speed range of 15-80 km/h.

Comment! During operating in the ETS mode, the effect is only on the leading ones, i.e. rear wheel.

As in the ABS system, braking in the ETS is carried out in three phases:

  • creating pressure
  • pressure maintenance
  • depressurization

The difference is that the driver does not take part in the process of slowing down the spinning wheels. All three phases are carried out by the ETS, namely: the fluid pressure in the braking system is created by the pump and controlled by the solenoid valves of the hydraulic unit.

When the driver presses the brake pedal or when the wheel slip stops, the ETS control mode stops.

On vehicles with a manual transmission, in order to prevent engine shutdown due to an excessively strong braking effect when starting off, a corresponding protective function is built into the control unit. Control block calculates the minimum permissible number of revolutions of the rear wheels, corresponding to the minimum permissible engine speed and when approaching this value reduces the braking effect.

ETS has the function of protecting the brakes from overheating. When a certain temperature is reached, the braking effect on the corresponding wheel is not carried out until the temperature drops. The ETS indicator light comes on in the instrument cluster. The temperature is not measured directly, but calculated for each wheel, based on the duration and intensity of the braking effect, air temperature and vehicle speed.

In order to keep the information on the temperature of the pads when the ignition is switched off, the control unit has a delay function. At the same time, the supply voltage is applied to it, and it calculates the temperature until it falls to 85 F, but no longer than 30 minutes, and then turns off.