It's all about the ABS sensor

ABS - Anti-Lock Braking System

ABS - Anti - Lock Braking System

By law, the vehicle must brake even when all brake systems fail. What exactly does this mean? This means that the car will brake even when your brakes have failed, but, of course, not optimally, the braking distance will be much longer and riskier.

Older cars rely less on more brakes, while newer production vehicles have an ABS system as part of the mandatory equipment. It is usually controlled by a sensor and it is this sensor that in most cases is the cause of the failure when a failure occurs on the ABS system.
When we say ABS, it seems to us that it is something very complicated, but it is actually a very simple system. To begin with, it should be said that ABS is an abbreviation for 'anti-lock braking system', and it is a system that allows the vehicle, or its tires to remain on the road surface during braking, prevents it from slipping off the road and is therefore an act. braking much safer and faster.
The central unit of the ABS is in constant control over the rotation of each of the wheels and compares them. When the rotation speed of one of the wheels is at zero or significantly lower than the rotation speed of the other wheels, the system reacts by reducing the braking force at that point and slowly releasing it to start spinning normally again. When it starts to spin, the system increases the braking force, and we feel it on the brake pedal like a vibration.
ABS distributes the braking force to the rear and front axles. In this whole system, the sensors are very important, and there are sensors that monitor the rotation of the wheels, the ring of the signal sensor and the unit that processes the signals and controls the entire ABS system. Today we know two types of sensors and three types of signal transmitters. One type are analog ABS systems with by inductive sensors, and the other are modern, magnetic systems with a magnetic signal transmitter. Analog ABS systems are quite large and they have quite a few voltage spikes that are recorded on the central unit. The more such jumps, the higher the speed of movement. The sensors must react to the ring, and in order for that to happen, a certain gap is needed, which must be around 0,6 millimeters. It is in this part that a fault usually occurs, because the gap is disturbed and in that case the sensor does not catch the sensor. These, old sensors can really last a long time and some are older than 15 years, and then they simply fail.
Whether this type of sensor is faulty is easy to detect with a multimeter because the resistance must be between 1100 and 1200 Ohms. If the resistance is larger, the system may work but will not be correct, and if the resistance is zero, the sensor fails.
When we talk about modern ABS systems, they have a lot of small magnets on the ring that are so complex that they replace the north and south poles on the outside, and the sensor records all that. This type of system can also be checked with a multimeter, but the correct resistance is 1600 Ohms. With them, the gap is much larger, it is around 4 millimeters, so their field of tolerance is wider.
As technology in cars is constantly evolving, it should be known that there are also ABS systems that have signal transmitters that are integrated into the bearings thus greatly simplifying the entire system.
Practice shows that the sensor is the most common cause of failure on the ABS system, and its replacement is easy and not too expensive.

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