Electronic Program System (EPS) in the car - what is it and system features

Most modern cars equipped with systems that make the car easier to operate and increase the safety of movement. At the same time, electronics "additionally" expand the functional capabilities of the vehicle. Electronic Program Stability is one of the most common systems.

What is EPS

It cannot be physically felt by hand - we are talking about special software, which includes two small ABS and ASR systems. The first of them prevents the wheels from locking during emergency braking, so that the driver can still control the car. The second (it includes all the features of ABS) prevents slipping. At the same time, the system regulates the operation of the power unit. That is, ASR affects both the engine and the braking system.

When was EPS introduced?

For the first time, course stabilization began to be used on their cars by Honda since 1990. The system only supplemented the already known then ABS. The innovation was just right, and soon most automakers began to equip their cars with EPS. The system has been constantly improved, but Mercedes-Benz has achieved the greatest success by first testing the program on the CL600 model. Since then, EPS has been included in the basic package of all Mercedes C-classes (and not only).

How EPS works

The system includes sensors that inform about the condition of the road surface, engine speed and speed. The system is also connected to the electric power steering. The electronic program is connected to the chassis of the car and its power plant in order to stabilize the movement of the car in various driving situations.

The operation of the system is to act on one or both drive wheels by braking. If necessary, the amount of the fuel mixture supplied to the cylinders is automatically reduced (as a result, the speed decreases, the speed of the car drops). Engine operation is adjusted by means of an ECU that performs the functions of a tempomat (constant speed support - cruise control) and an electronic gas pedal. The system, simultaneously taking into account the data from the power steering, stabilizes the movement of the car during straight-line movement, entering a turn, maneuvering. Ultimately, EPS keeps the car within the trajectory set by the driver.

The system begins to work from the very beginning of the movement and operates at all speeds. EPS receives data on the number of revolutions of each wheel (not just the driving ones) and calculates the theoretical speed of the vehicle. In terms of functionality, it resembles the same ASR, but there are differences that consist in the use of additional sensors that:

• ✅ calculate the steering angle
  
• ✅ determine the position of the accelerator pedal
  
• ✅ "know" everything about the behavior of the car - its movement around the vertical axis, lateral acceleration and the number of wheel revolutions
  

More about the system

If the ESP, after reading the information from the sensors, "sees" that the behavior of the car does not correspond to the desire of the driver, then the situation will be defined as uncontrollable. Based on the received data on the acceleration in the transverse direction and the number of revolutions of the engine, EPS makes calculations about the forces that tend to move the car from a given trajectory. Next, the program “develops” ways to get out of a dangerous situation. That is, it slows down one or more wheels, reduces (if necessary) the engine torque by closing the throttle. It also gives a command to the electronic unit of the automatic transmission so that it does not shift to a lower gear. When the car returns to "its" trajectory, the effect on the engine, brakes and steering stops. It takes 20 milliseconds for "everything about everything".

How EPS fights rear axle skid and loss of control

In this situation, the front left wheel, which runs along the outer radius, and both rear wheels begin to slow down. This makes it possible to quickly exit the side skid. At the same time, the engine speed decreases, the wheels begin to rotate more slowly.

System shutdown

The need for this may arise for various reasons. Here is some of them:

• ✅ drive on a difficult road - deep snow, sand, ice, grass
  
• ✅ pulling out a car stuck in a ditch or anywhere else
  
• ✅ when testing the machine on stands in specialized technical centers
  
• ✅ when installing wheels of different diameters
  

Equipping security systems for serial cars

In Western Europe, this is the rule. Almost all cars coming off the assembly line are equipped with safety systems. As for Russia, until 2011, not all brands of vehicles were equipped with a dynamic stability program. Since 2016, electronic stability control has become mandatory for of buses, trailers, any types of commercial vehicles.

What gives the EPS connection

In addition to ensuring traffic safety and getting the car out of emergency situations, the presence of the system provides other advantages:

• ✅ reduction in fuel consumption caused by a drop in energy costs for the operation of the power steering
  
• ✅ the ability to independently change the standard EPS settings by the driver (meaning a decrease or increase in the sensitivity of sensors to maneuvers)
  

Features of using EPS

The system is quite reliable, and does not require any action on the part of the driver during operation. But, like any other electronic device, it has its weaknesses. One of the possible problems is a program crash. When it occurs, the control lamp on the dashboard lights up.



In garage conditions, it is very difficult to understand what caused the software to fail and restore its normal functioning - special diagnostic equipment will be required. The best option is to contact a specialized service. Setting up the program does not take much time. Self-attempts to repair can lead to even greater problems and, as a result, increased financial costs in the future. But if you are confident in your abilities, you can first reset the EPS errors. The following describes how to do this using the Honda Accord as an example:

• ✅ turn off the ignition, find the diagnostic connector and close (with a paper clip, wire, etc.) pins 4 and 9
  
• ✅ turn the steering wheel all the way to the left and hold it in this position
  
• ✅ turn on the ignition - the EPS lamp will light up and go out after 4 seconds
  
• ✅ release the steering wheel so that it returns to the middle position, after the same 4 seconds, the alarm will light up again
  
• ✅ repeat procedure #2 and #4
  
• ✅ when the steering wheel is in the middle position, the EPS indicator will blink a couple of times, indicating that the memory has been reset
  

It remains only to turn off the ignition and pull the jumper out of the connector - the errors are reset.

Is it possible to constantly rely on ESP?

The system helps to adjust the directional stability of the car, corrects some driver errors and removes the car from situations associated with skidding, slipping and poor road surface quality. But do not forget that EPS is not a panacea for all ills, it cannot completely eliminate accidents. For example, the program does not guarantee safety at a small turning radius at high speed. Therefore, you need to carefully evaluate the traffic situation and, above all, rely on your own strength and experience.