How to find an ABS malfunction without knowledge in electrics - step by step instructions

A lighted up ABS light is an unpleasant surprise that does not appear for no reason. Braking efficiency is reduced, which affects safety, especially in winter. It is not necessary to look for an auto electrician, any driver can carry out diagnostics, and it does not matter if he has experience in repair or not.


It makes no sense to disassemble the anti-lock braking system device and the principle of its operation. It's much easier to figure out what's going wrong. This is usually a fuse, wheel sensors, toothed or magnetic rings, or an ABS control unit. By checking the elements in turn, it is easy to find a breakdown in a short time.

work Features

In most modern cars, computer diagnostics can be carried out if there is a program and a connector for connecting. When there is no equipment, it is worth contacting the service station, where in 10-15 minutes they will find all the errors, by which it will not be difficult to find out what is faulty.

Older cars may have a self-diagnostic function. To use it, you will need a user manual for the model. It is usually necessary to bridge certain pins in the connector. Then count how many times the control light flashed and find out from the manual what is out of order.

If it is not possible to use one of the methods described or the machine is old, you will need a multimeter to work. It is best to buy an inexpensive electronic model, it is much easier to take data from it.

Fuse

You need to start checking with it, following the principle “from simple to complex”. Follow these guidelines:

• ✪ Determine where the correct fuse is located. The block can be both in the cabin and under the hood, it all depends on the model of the car. The cover should have a detailed diagram indicating the purpose of each element and the current strength for which it is designed. If there is no information, find it in the instruction manual or on the Internet.
  
  
• ✪ Carefully extract the desired option. They are arranged tightly, so it is best to use special tongs. They come with a set of spare fuses. Inspect the element, if there is carbon deposits on the contacts, the jumper is melted or has signs of damage, replace the part.
  
  
• ✪ If the tongs are not available and cannot be removed, it can be checked in situ. To do this, the fuses have metal contacts at the top. Set the multimeter to the dialing mode (it is marked with a sound signal symbol or an arrow resting on a line). Press the probes, if the device beeps - everything is in order. When silent - the integrity is broken.
  
  
• ✪ If for some reason it was not possible to determine the exact position of the ABS fuse, you can ring all the elements in order, it will take a couple of minutes.

SENSORS

They are checked on each wheel separately. Starting from the back right. Raise the car with a jack, put a support and remove the tire to provide access. The work consists of several stages:

• ✪ The wires to the connector are covered with a plastic locker. It is easily damaged when removed, so you must carefully unscrew the screws or snap off the latches. The plug is most often located in a small box or fixed on the inside of the arch. Disconnect carefully: press the plastic clips with a flat screwdriver and carefully pull in different directions.
  
  
• ✪ Inspect contacts, assess their condition. Corrosion and oxidation are most easily removed with an electrical contact cleaning spray. It not only removes plaque, but also protects the connection in the future. If there is a lot of rust at first, it is recommended to remove it with sandpaper or a small needle file. In case of severe damage, it is better to replace the connector.
  
  
• ✪ If everything is in order with the contacts, check the sensor. To do this, set the multimeter to the resistance measurement mode and press the probes to the contacts in the plug. The indicator should be from 500 to 900 mA (in some models it may differ, it is better to find information in advance). When the value is zero, the node is faulty.
  
  
• ✪ With normal readings, there is no need to rush to remove the device. Without removing the probes from the connector, it is necessary to turn the hub several times, while the data should jump. If the readings do not change, the magnetic or gear ring is out of order, sometimes it becomes very dirty and cleaning helps. But most often you have to change this detail.
  
  
• ✪ If there are no problems, check if voltage is applied to the sensor. Set the multimeter to measure direct current (value 200), press the probes to the contacts coming from the vehicle wiring. Turn on the ignition without starting the engine. Check the voltage, most likely it will be small, but this is normal. At zero readings, you will have to look for the place of damage to the wire by ringing the circuit.

Sometimes the problem occurs due to the banal contamination of the sensor where the working part comes out of the hub. This area should be carefully cleaned with a brush.

So you should check each wheel until a malfunction is detected. If you are lucky and the problem is detected immediately, you can not continue. Most often, one node fails, the failure of two is a rarity.

Other reasons

On many cars that are over 10 years old, a relay is included in the ABS system. Therefore, you need to study the diagram and, if there is such a node, remember its location. Carefully remove and inspect the contacts, if they have carbon deposits or signs of overheating, you need to replace the failed part.

It is often impossible to identify a broken relay by its appearance. It is best to remove the same from the block and install it on the ABS system, then turn on the ignition. If the signal light on the panel stops burning, you need to buy a new element with the same characteristics and install it. Do not forget about the continuity of the electrical circuit. With a multimeter, you should check whether the relay is energized, as wiring problems can occur with age.

If everything is in order with all the above elements, you need to check the ABS control unit. Often it is located inconveniently - on the partition of the engine compartment or even from below. You should figure out in advance how to provide access, often this requires a flyover or a pit.

Carefully remove the wiring harness. There is a waterproof connector with latches that need to be pressed out. It is important not to damage the connection, otherwise moisture will get there. Inspect the contacts, if there are signs of oxidation, you need to use a cleaning agent, plentifully processing the connector itself on the case and the wiring block.

After cleaning, reconnect and check the operation of the anti-lock system. If the light does not go out, the ABS control unit is most likely faulty. It will not work, in this case you will have to look for a new part and change it.

If you buy a cheap multimeter and follow the instructions from this review, you can find a problem without computer diagnostics and contacting a service station. The main thing is to be careful when disconnecting the connectors. The plastic on them becomes brittle over the years and breaks easily if excessive force is applied.