How to turn on the traction control system in Mercedes Benz?

In this blog,  we will find out how to turn on the traction control system in Mercedes Benz. In addition, this blog will also explain the components in the traction control system and provide answers to the following questions: what are some of the problems in the TCS in Mercedes Benz cars? What is a road test active fault code in TCS?

How to turn on the traction control system in Mercedes Benz?

The traction control system in Mercedes Benz cars is turned on by default, simply turn on the ignition and start the car. The traction control unit light in the instrument cluster will turn off indicating that no faults are present in the system. To turn OFF the traction control system press the TCS button located in the upper control panel.

As the traction control system is one of the important driver assistance systems, Mercedes Benz has removed the dedicated ESP or traction control system OFF switch in the models manufactured after 2014.

The ability to toggle the traction control system is still present in the vehicle but it is not easy to access the menu. If the vehicle is on a dyno, then it is necessary to turn off the traction control system since only the drive wheel will be turning on a dyno.

Mercedes Benz AMG models still feature the TCS toggle switch but these cars are high-performance models. Customers use the AMG models for race tracks when the traction control system can be intrusive to the driver. On normal roads, keeping the traction control system ON can ensure the vehicle stays under control. 

What are the components in the traction control system used in Mercedes Benz cars?

The traction control system is comprised of the following components

  • Steering angle sensor

It is located in the steering column module control unit, the sensor is fixed very near to the actual steering shaft. The hub gear wheel of the sensor converts the rotary movement of the shaft into a voltage signal. This signal is then measured in degrees by the steering column module and then transferred to the ESP control.

  • Acceleration sensor

It is located on the body of the vehicle, in most Mercedes Benz models the location is under the front passenger seat. It is used to measure the wheel and body acceleration in the direction of the vertical axis of the vehicle. 

Body acceleration sensors can detect the oversteer or understeer, in some high-performance models, there are two acceleration sensors located on the front and rear axle. Based on the data from the acceleration sensors the traction control system can cut the power to the engine and regain control.

  • Throttle position sensor

The throttle position sensor is located in the accelerator pedal, it has two potentiometers. The engine control unit determines the throttle position and adjusts the throttle valve angle. In models with diesel engines, the fuel injection quantity is determined by the throttle position sensor.

When the traction control system detects wheel slip, the engine control unit will cut the throttle response until the driver regains control. This is also known as traction control system cut, in Mercedes Benz cars there is no setting to adjust the traction control system cut. The engine control system can reduce 100 percent power if the vehicle is losing traction.

What are some of the problems in the traction control system of Mercedes Benz cars?

The common problems observed in the traction control systems in Mercedes Benz cars are as follows:

ABS/ESP inoperative

The traction control system is integrated into the ESP control unit, ESP stands for electronic stability program. It monitors the wheel speed when the vehicle is in motion. The body acceleration sensors are located under the front passenger seat and give real-time data to the ESP control unit.

With the data from the wheel speed sensors and the body acceleration sensor, the traction control system can determine oversteer or understeer caused due to the lack of traction. Based on the type of loss of traction, the TCS can take counteractions and keep the vehicle in control.

If the wheel speed sensor is giving an incorrect signal and the actual value calculated from the ESP control unit is outside the specified range of 0.0 km/hr 250.0 km/hr, the ESP control unit will become inoperative and the TCS system will not function.

Incorrect steering angle 

A steering angle sensor is located in the steering column module or SCM. The SCM is an integrated control unit connected to the ESP over the chassis CAN. The traction control system monitors the steering angle measured by the steering angle sensor.

The steering angle is very important for the correct functioning of the TCS as the driver will try to correct the understeer or oversteer. Therefore, based on the steering inputs of the driver, the traction control system will intervene and assist the driver to regain control of the vehicle.

When the steering angle sensor malfunctions, a fault code or DTC is logged in the SCM control unit and the traction control system will become inoperative. The only remedy is to replace the steering angle sensor.

In the latest models, the steering angle sensor is integrated into the steering column model control unit. Hence the complete steering column module control unit is replaced. After replacing the faulty part, control unit programming is performed.

What is a road test active fault code in the traction control system?

Road test active fault code occurs when the ESP or traction control system is replaced and the programming is not completed successfully. When this fault code is present, the traction control system light blinks in the instrument cluster and the complete ESP control unit is inoperative.

To complete the road test procedure successfully, the vehicle must be driven in a semicircle with a full steering lock. After completing the half circle turn the steering to the fully opposite lock and drive in a semi-circle on the opposite side.

Bring the steering wheel to a straight position and put the transmission in the P position. The TCS and the ABS light in the instrument cluster should turn off if the procedure is completed successfully.

The road test active procedure may require a couple of attempts as the traction control system is calibrated according to the data from the steering angle sensor and body acceleration sensors.

Conclusion

This blog explained the procedure to turn the traction control system ON and OFF. Turning the traction control system off is not recommended in normal driving operations as it can be helpful, especially in wet or slippery driving conditions. If there are malfunctions related to the traction control system in the vehicle then visit the nearest authorised dealership for further diagnosis and rectification.

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