At the moment, almost everyone, when purchasing a new car, can order the optional installation of any system from the dealer. This has become quite commonplace. But there are options that are already included in the package, and you don’t need to pay extra for them.
Among these is the SRS system. What is it and what components does it contain? You will find out the answers to these questions in our article today.
Characteristic
SRS - what is it? This system is a set of elements installed in a car that can reduce the consequences of road accidents for the driver and passengers. According to its classification, the SRS Airbag belongs to the structural safety elements. This means that all its components are not installed optionally (as may be the case with an air conditioner), but rather mandatory. And it doesn’t matter whether it’s a top-end or a “base” configuration, both cars will still contain the same set of passive safety devices.
Thus, SRS is a set of structural elements that are used to protect passengers and the driver from injury in an accident.
ABS error reset for Honda vehicles
In order to reset the ABS error, you need to find a 16-pin diagnostic connector if there is one; if you have a connector that is not 16-pin, see the diagnostic connector pinout section and follow the diagram - connector pinout
We close contacts 4 and 9
Explanation and location of contacts for obd 2 16 pin on Honda cars
Once you have found the connector, make sure the ignition is turned off and connect pins 4 and 9.
Once closed, follow the instructions.
1) Press the brake pedal 2) Without releasing the brake pedal, turn the key to the ignition position. The ABS light should go out after 2 seconds. 3) After the ABS light goes out, release the brake pedal. The ABS light should come on again after 4 seconds. 4) After the ABS light comes on again, press the brake pedal again. Keep it pressed for 4 seconds until the ABS light goes out. 5) When the ABS light goes out, release the brake pedal. 6) After 4 seconds, the ABS light should blink briefly 2 times, which actually means all errors from the memory have been deleted. 7) Turn off the ignition.
The error reset is now complete.
System components
The SRS system may include the following components:
- Seat belt (usually three-point and installed on each passenger and driver seat).
- Belt tensioners.
- Emergency battery breaker.
- Airbags (in the 90s they were considered an invisible luxury for car enthusiasts).
- Active head restraints.
Depending on the make and model of the car, SRS may include a number of other devices. For example, this could be a rollover protection system (as on convertibles), additional mounts for child seats, etc.
Recently, many cars have begun to be equipped with pedestrian protection elements. Some models even have an emergency call system.
Passive safety control SRS
We have already found out what kind of system this is, now let's look at how it is controlled. But not everything is so simple here. All the elements listed above are electronically controlled, which ensures the effective interaction of the various SRS components. What does it mean? Structurally, this system is a set of various measuring sensors, a control unit and actuators. The former perform the function of recording the parameters in which an emergency situation occurs and convert them into short electrical signals. These may include impact sensors, front seat position sensors, and 3-point seat belt buckle switches. As a rule, the automaker installs 2 such devices that react to impacts on each side. Also, these sensors are closely connected with active head restraints, which, when a signal is given, go into active mode.
Thus, each of the components of the passive safety system closely interacts with certain sensors and, due to special impulses, allows the Airbag and its other components to be inflated through the SRS unit in a matter of milliseconds.
EPC errors by model
There are hundreds of errors and malfunctions signaled by EPC. Naturally, it is impossible to list them all. Everything is designed for the car owner to contact the service center. But, as they say, each model has its own characteristic problems, which owners complain about on specialized forums. Below is a short summary of some of the brand’s models.
Q5
The EPC indicator on the dashboard of Audi Q5 owners often displays the following errors:
- The error is accompanied by a “Check Engine” indicator and indicates a malfunction of the gearbox control unit processor. It will be necessary to either replace the entire unit, or a connector, or several wires;
- This EPC error on the Audi Q5 indicates damage to the limit switch going to the clutch pedal. Replacement only;
- The error is displayed when the climate compressor clutch relay is faulty. The repair consists of replacing the relay or the clutch itself;
- Plug control module failure. Replacement of wires, spark plugs, relays or the module itself is required.
Interestingly, for many Audi Q5 owners, the EPS light came on when Ingolstadt rolled out new firmware, which was proposed to be installed on a voluntary-compulsory basis.
EPC error on Audi Q5 dashboard
A4
If you look at the “branch” of owners of the A4 model, their “sores” are revealed here. For example:
- No signal from the automatic transmission torque converter turbine. The problem is solved by replacing the oil, temperature sensor or valve body. Depends on a situation;
- Incorrect signal from the engine speed sensor. It will need to be replaced or visually inspected for corroded wires;
- Problem with the gear ratio in the gearbox. Repair depends on the nature of the damage. Starting from replacing wires and an oil pump, ending with a complete replacement of the gearbox.
How to remove the USS error on the Audi A4 1.8T, see the video below:
A6
For the Audi A6, motorists also often ask about errors such as:
- There is a malfunction in the speed sensor. The repair may not be limited to a pair of wires or the sensor itself. From time to time you have to replace the entire ECM module;
- Motor control module temperature is high. During repairs, grounding and fuses are checked. If necessary, the module is changed;
- Abnormal voltage in the fuel level input circuit. Repair may be limited to replacing wires and connectors, or replacing the PCM.
To summarize, there are hundreds of errors in the EPC system and each one signals a specific problem. This greatly simplifies the repair of high-tech cars and helps to prevent serious engine and gearbox malfunctions in time, before the cost of repairs exceeds the cost of the car itself.
EPC error and check engine light on VAG cars is the topic of this video:
Execution devices
Among the execution devices in the car, the following should be noted:
- Belt tensioners.
- Pillow squibs.
- Headrest drive mechanism.
- A warning light on the vehicle's instrument panel that indicates seat belts are not fastened.
Activation of each of these components occurs in accordance with the software provided by the manufacturer.
CPC safety devices that execute commands from the control unit
The performing elements of this system include:
- Seat belt tensioners.
- Airbag cartridges.
- The mechanism that controls the head restraints.
- A warning light, an indicator notifying that the seat belts in the car are not fastened.
The above devices are driven by software installed by the manufacturer.
Many people have difficulties setting up the car alarm key fob, for example, after replacing the batteries, they cannot set the time or timer. Approximately, all remote controls have the same principle for setting up Starline or other brands of alarms.
What devices can be activated in a frontal impact?
In the event of a frontal collision, SRS can activate several safety elements at once, depending on the severity of the collision. These can be either tensioners or pillows (possibly all together).
In the event of a frontal diagonal collision, depending on the angle and magnitude of the impact force, the following are activated in the system:
- Belt tensioners.
- Front airbags.
- Pillows with tensioners.
- Left or right Airbag.
In some cases (usually at speeds above 60 kilometers per hour), the system can activate all of the above elements, thereby ensuring maximum safety and minimal risk of injury to passengers in both rows of seats, as well as the driver himself.
Principle of operation
Here are the main elements of the SRS system and how they work:
Airbags
Unfortunately, today there are no regulations that would allow us to establish uniform standards for the development of pillows. Nevertheless, the developers are trying to protect the lives of passengers by improving the system. The pillow itself consists of a shell and a mechanism that supplies the filling. The airbag cable connects it to the squib.
When the system is triggered, under the strong influence of the incoming filler, the pillow opens the interior elements of the car in the places where it is installed. The system can only be activated when the ignition key is turned to the start position.
In the most common SRS, the response speed of the airbags in a frontal collision is approx. 0.04-0.05 s, deflates after 4-9 s. Such a reaction largely depends on the system itself, the design of the car body, the location of some of its components and the material from which the deformable zones are made. The purpose of an airbag in a collision is to inflate before it touches the person's body. Otherwise, when fired, the passenger will recline. This can be not only traumatic, but even fatal, since the shell opens at a speed of approx. 300 km/h.
Seat belts
Most often they are equipped with pre-tensioners. This allows the passengers to be held in place and, at the appropriate moment (after approximately 0.03 s), to release slightly, ensure an accurate hit on the cushion. This is a very important point, because when a car collides with a stationary surface at a speed of 50 km/h, the body presses against the seat belt with a force equal to almost three tons. Without a seat belt, in such a collision the human body can withstand a load of only 300-400 kg. Therefore, it is obvious that passengers who do not wear seat belts increase the chance of death many times over.
Sensors
The sensors typically respond to a decrease in vehicle speed during a collision. The average response threshold is 15g5. This magnitude can only be achieved by impact. This protects against false triggering of the sensor when the car skids or sharp braking.
Airbag control unit
We can say that this is the processing center for all information coming from the system. He is entrusted with the procedure for analyzing the strength and duration of the signal supplied by the sensors. The block ignores certain signal bursts. In order for the signal to be taken into action, it is necessary to overcome a threshold of 0.003 s. In addition, engineers have developed additional pulse blockers.
So, if the car speed is less than 20 km/h, the sensor will not work. This allows you to protect passengers from the consequences of false signals, for example, when parking.
What devices can be activated in a side impact?
In this case, depending on the vehicle’s equipment, either the belt tensioners or the side airbags may work. The latter are usually installed on cars of middle and more prestigious classes. Budget cars are equipped only with tensioners, which are activated upon impact, fixing the person’s body in the seat.
Also, depending on the force of the impact, the battery disconnect switch in the car is triggered. Thus, in the event of a collision, the risk of a short circuit or spark formation is completely reduced. This reduces the possibility of unauthorized ignition of the vehicle as a result of a hole in the gas tank or other deformations of body parts.
What are active head restraints?
These elements began to be equipped on cars much later than classic seat belt tensioners. Typically, active head restraints are installed on the backs of the front and rear rows of seats in the cabin. Thanks to the presence of such elements, the risk of a fracture in the cervical region during a rear impact is reduced to a minimum (and this is precisely the area that is one of the most vulnerable to fractures). Thus, active head restraints significantly increase the chances of survival even in seemingly fatal impacts. The first copies of such devices began to be installed on German Mercedes. According to their design, these head restraints are divided into two groups and can be either active or stationary. In the first case, the headrest can be adjusted in height and angle. The stationary analogues are rigidly built into the seat backs. However, even such head restraints do an excellent job of their main function – reducing the risk of injury in various types of collisions.
So, we found out what the SRS system is in a car and how it operates in various collisions.
