Automakers strive to make their products as safe as possible, for this purpose in sedans, hatchbacks, crossovers, etc. additional systems and nodes are installed. These modules include the ABS, which allows to ensure straightforward movement of the vehicle during heavy braking on difficult pavements.
With frequent operation, individual elements wear out, and it is necessary to carry out diagnostic work to detect breakdowns. Let us figure out how to check the ABS sensor with a tester in various cars, because with its help electronic pulses are transmitted to the ECU (electronic control unit).
Content
- 1 Sensor performance
- 2 Troubleshooting
- 3 Conducting a voltage test
- 4 Alternative verification methods
Sensor performance
The sensor operates in conjunction with a special toothed comb, and is an induction coil. Information is analyzed in the computer, and as a result, the pressure on the brake cylinders is adjusted through the hydraulic system.
The most common faults that occur in these nodes are related to the open circuit between the control unit and the sensor itself. Also the unit may fail due to mechanical or electrical damage, in this case, the pulse is incorrectly transmitted to the ECU.
ABS sensor
Possible malfunctions are signaled by a special light sensor on the dashboard. For more accurate diagnosis, you must use special devices.
troubleshooting
Testing the ABS sensor with a tester is done independently after the indicator lights up. Also need a car manual and an assistant. Contacts with the necessary pin-connectors are pre-rendered.
Work is performed in the following sequence:
- the car is lifted with a jack or hung out on a special lift;
- for convenience of access to the sensor dismount the wheel;
- from the back of the hub unwind fasteners, fixing the desired node;
- we get rid of the casing on the ABS unit and open the connections to the controllers in it;
- we put a repair cable with PIN contacts onto the tester, and connect the other end to the sensor socket;
- measure the resistance on the contacts and compare the readings with the factory parameters specified in the instruction manual of the car;
- to “call” the wiring for the absence of a short circuit with the ground.
After these works, we rotate the wheel by hand, and we measure the resistance. This operation requires someone's help. While changing the wheel speed, the data on the multimeter should also vary and respond to this speed.
The resistance of the ABS sensor is usually in the region of 1 kΩ (1000 Ω). It depends on the specific model of car, as all sensors are different. So, for example, in one model, 600 ohms will be considered the norm, and in the other 1350 ohms.
Conduct voltage test
The performance monitoring of the sensors can be performed using the “voltmeter” mode on the multimeter. The operation is performed on each of the sensors in turn. To do this, you must perform the following algorithm:
- alternately jacking up the necessary side with the wheel;
- connectors of a pin-cable connect with a tester;
- the wheel will need to rotate with the most accurate frequency of 1 rev / sec.
The multimeter should show readings in the range of 0.25-1.20 V. As the rotational speed increases, there should be a tendency to increase the voltage reading on the tester screen.
Alternative verification methods
In addition to the multimeter, testing can be performed using a more informative instrument for this, for example, an oscilloscope. It forms a graph on the monitor, the amplitude of which determines the resistance level. However, this device is quite expensive for home use and needs qualified maintenance by a specialist.
The oscilloscope can be met at specialized stations that are professionally involved in car diagnostics.
Many ABS systems in modern cars have a self-diagnostic function. By activating this function, the driver will receive a special error code encrypted with numbers and letters on the on-board computer monitor. To understand the decoding will help the instruction manual of this model of car.
Oscilloscope operation
Faulty sensor can be replaced by yourself. Before the procedure, you must order from the authorized dealer this item.
The updated sensor should be tested on a flat road, braking from a speed of 20-40 km / h. To do this, the brake pedal must be squeezed sharply into the floor. When working properly under the driver’s foot, the pedals will feel slight vibration transmitted from the work unit. You should also hear the characteristic sound of the brake pads. If necessary, and carried out the replacement wiring. As a result, there should be the same system test results.
See also: Why brake pads creak
