How to bleed brakes with abs (ABS): step by step instructions. Replacing the brake fluid For effective pumping, while working with the brake system of the rear left wheel, the procedure must be corrected

1. First, we look for and remove the fuse in the fuse box that is responsible for the operation of the anti-lock braking system.
2. Next, we jack up and remove one front wheel, and look for the fitting of the working brake cylinder (RTC).
3. After that, we put a hose on the fitting (from the hydraulic level, for example).
   
   
4. We open the fitting one turn.
   
5. One presses the brake pedal all the way and holds it in that position.
   
6. Now we turn the ignition key to turn on the hydraulic pump (the ABS indicator lights up on the instrument panel).
   
7. The second person watches how the air is removed through the hose and, after removing the air, tightens the fitting.
   
8. We release the brake pedal only after tightening the fitting.
9. Now, how do you know that all the air has come out of the ABS? This shows the ABS icon on the dashboard, if it went out after the air was removed and the fitting was tightened, then all the air was released.
   

The correct sequence for bleeding the ABS system

There is a special procedure for properly bleeding an anti-lock braking system: right front wheel, then rear, then rear right, and then rear left wheel. If in the process of carrying out such work, TJ leaked out of the system, it is necessary to fill the system with a new liquid. And for this you need to know which fluids can be mixed and how much brake fluid is needed to replace.

Operation sequence for front wheels:

1. Switch off the ignition (key position "0").
2. Remove the terminals from the brake fluid bottle.
3. We take a bottle with a small amount of brake fluid and a hose. We lower one end of the hose into the liquid, put the other end on the fitting and open the fitting with an open-end wrench. It is advisable to use a transparent hose from the hydraulic level so that it can be seen whether air bubbles come out or not.
4. Press the brake pedal and hold it in that position.
5. The second person (at the wheel) looks to see if the air came out, and after the air bubbles stopped coming out, he closes the fitting with a key.

How to bleed rear wheels with ABS:

The procedure is different for pumping the rear wheels. After the front wheels, you should pump the rear right wheel in the following sequence:

1. We also put the hose in a bottle of liquid and in the caliper fitting.
2. Squeeze the brake pedal to the end.
3. Turn the ignition key to position "2".
4. Hold the brake pedal until the hydraulic pump completely expels air bubbles.
5. Close the valve and release the brake.

For effective pumping, while working with the brake system of the rear left wheel, the procedure must be corrected. Namely:

1. As in other cases, we put on the hose, unscrew the caliper fitting 1 turn. When pumping with the rear left wheel, the brake does not need to be pressed immediately.
2. Turn the ignition key to start the hydraulic pump.
3. After the release of air, press the brake pedal halfway and close the fitting.
4. Next, release the brake and wait for the hydraulic pump to turn off.
5. We turn off the ignition.
6. We connect the disconnected connector of the brake fluid reservoir (TF).

This video shows how to bleed anti-lock brakes on Audi A4, Audi A6, Volkswagen Passat B5 and others.

Conclusion

After carrying out repair and maintenance work with the critical components of the car, before the trip, you must first check the tightness of the system and the performance of the vehicle components.

ABS - Anti-lock Braking System is a system against wheel locking during heavy braking. Due to the fact that the ABS prevents the car from “floating” on the road, safety is increased in emergency situations. The anti-lock braking system will work properly if the system is not airborne.

Watch a helpful video. Tests show that even a working ABS system is turned off at the end of the braking distance, so you still need to modify it with your foot.

The components of the anti-lock braking system in the form of a pressure sensor and a hydraulic unit are integrated into the standard brake circuit. In addition to them, wheel speed sensors and a control unit are installed. By analyzing the wheel speed, the system maintains the optimal pressure in the circuit, preventing it from blocking.

Analysis of types of existing systems

At first glance, changing brake fluid with ABS is a trivial procedure. However, the modern auto industry forces us to reckon with safety trends: in almost all cars, the anti-lock circuit is combined with the EBD brake force distribution system and the ASC traction control algorithm. However, ESP is often in charge of these nodes - the exchange rate stability system.

With such high-tech packages, the procedure should be carried out exclusively in authorized service centers. The reason is the need to connect a diagnostic scanner to the computer. For the same reason, it is impossible to replace it yourself on vehicles where the pump with a hydraulic accumulator and the valve system are made as separate assembly units.

It is only possible to service the system on your own on a car with this layout: the hydraulic accumulator and the valve block are connected in one unit.

Preparing to replace the brake fluid of a car with ABS: conditions and necessary tools

In the process of servicing the auto deceleration system, free access to the working cylinders of each wheel is necessary. Therefore, the most suitable place for work is a viewing ditch or overpass.

When performing the procedure, you will need an assistant and a set of devices:

• a set of open-end wrenches;
• a large-volume medical syringe and a hose corresponding to the diameter of the tip, about 10-15 cm long (an alternative is a pear);
• container for extracted brake fluid;
• tube 20-30 cm long; diameter - slightly smaller than the diameter of the fitting on the brake cylinders (to ensure tightness).

Technology for changing brake fluid on vehicles with a combined hydraulic accumulator and valve block

The operation of replacing the brake fluid in an ABS system is carried out in several stages:

• draining the existing composition from the tank;
• pumping highways;
• pumping the ABS module.

The task of draining the working fluid from the expansion tank located in the engine compartment is solved as follows:

• pump out liquid from the tank with a syringe;
• fill in a new composition to the maximum mark (MAX, High);
• close the container.

After turning off the ignition and disconnecting the power blocks on the tank cover, you should proceed to bleeding the hydraulic system. The classic purge cycle looks like this:

• put the hose on the fitting of the brake cylinder located behind the wheel (lower the other end into the previously filled container);
• unscrew the fitting with an open-end wrench by 1 turn;
• 3-5 times push the brake pedal and hold (performed by a partner);
• after the end of the fluid leak, close the fitting and release the pedal.

Notes:

• the criterion for stopping the repetition of the cycle is the absence of air bubbles and visually clean liquid, indicating the removal of the old working fluid;
• since in the system under consideration the rear brake line is under high pressure, only the front brakes can be pumped in the classical way (first the left, then the right).

The bleeding of the rear circuits connected to the ABS equipment is carried out together with the bleeding of the anti-lock module. Actions with the right rear cylinder:

• connect the drain hose and open the fitting;
• press the brake pedal;
• turn on the ignition;
• after the cessation of the release of air bubbles and the appearance of a new composition, wrap the fitting;
• release the pedal;
• turn off the ignition.

After replacing the brake fluid in the three circuits of the ABS system, bleed the rear left line:

• connect the hose to the fitting and unscrew the latter by 1 turn;
• turn on the ignition;
• note the end of the exit of air bubbles and the new composition;
• give a command to a partner to press the pedal half way;
• turn the fitting;
• release the pedal;
• wait for the end of the pump (voiced sound frequencies should be replaced by low ones);
• turn off the ignition.

After the operation is completed:

• bring the liquid level to the maximum;
• connect the connectors to the tank cover;
• check lines for leaks.

Alternative solution to the issue

The owner's manual for a vehicle with ABS may indicate the presence of a drain fitting in the design of the anti-lock module. To service such a system, you may need a compressor or a home-made installation in the form of a pear and a modified tank cap. The replacement technology in this case looks much simpler:

• remove the used liquid from the container and fill in a new one;
• bleed all four brake cylinders using the classical method according to the scheme specified by the manufacturer;
• install a special adapter for a compressor or a home-made installation instead of the “brake reservoir” cover;
• connect a hose to the drain fitting of the anti-blocking module and unscrew it by 1 turn;
• create a pressure of about 1 BAR;
• identify the end of the exit of the old liquid and bubbles;
• relieve pressure.

In the process of replacing the used brake fluid with a new one in an ABS system, the following points should be taken into account:

• constant monitoring of the liquid level in the tank is necessary: ​​a decrease below the minimum mark (MIN, Low) is not allowed;
• admissible operating time of the hydraulic pump is 2 minutes, if it is exceeded, turn off the ignition and let the unit cool down for 5-10 minutes.
• before draining the fluid, it is necessary to “discharge” the system by pressing the brake pedal at least 20 times;
• it is strictly forbidden to pour the used liquid or the composition that has stood in an open container for a long time;
• when the ignition is turned on and the drain fitting is open, you should be prepared for a sharp release of liquid.

Summary

It is possible to independently change the fluid only on cars with a hydraulic accumulator and valves combined into one unit. List of required equipment:

• syringe with extension tube or pear;
• transparent container;
• transparent tube 20-30 cm long;
• open-end wrenches on "8" or "10".

Briefly about the procedure for replacing the brake fluid in a car with ABS on its own:

• replace the composition in the tank with a new one;
• bleed the left and right front brake cylinders;
• pump the rear right cylinder with the brake pedal depressed and the pump turned on;
• bleed the rear left cylinder with the brake pedal released and the hydraulic pump turned on;
• check the system for leaks.

If there is a drain fitting on the ABS module, it is necessary to bleed all 4 brake cylinders using the classical method according to the scheme specified by the factory, and then “drive” the ABS installation with excess pressure supplied from the outside.

Reading 6 min. Views 1.6k. Posted on October 30, 2015

In this article we will tell you how to properly bleed the brakes with ABS.

Signs you need to bleed your ABS brakes

Air also enters the anti-lock braking system. Since the circuit of such a brake system is hydraulic, air significantly impairs its performance. Determining the accumulation of air in the circuit of the brake system is quite easy. If the kickback of the brake pedal becomes softer when pressed, it means that air has appeared in the brake system.

Air can enter the ABS brake system in the following cases:

— When repairing the hydraulic drive of the brake system;

- When replacing a caliper on one of the wheel hubs;

— In case of a long idle time of the car;

- In the case of ongoing repairs of various components of the vehicle's brake system;

- When replacing the entire volume of brake fluid in the circuit.

A modern anti-lock braking system consists of the following main components:

- hydraulic accumulator,

There are a number of car maintenance jobs that the average car enthusiast dreads. Man is always afraid of what he cannot explain. It would seem that pumping the brakes - what could be easier? But if you add the abbreviation ABS to this phrase, then it just makes your hair stand on end. In fact, everything is elementary simple and knowledge of physics at the level of the sixth grade of a comprehensive school is quite enough to properly replace the brake fluid and pump the brakes.

Working Principle of Hydraulic Brake System

All hydraulic brake systems are fundamentally the same, and it does not depend on whether the car has ABS or not. The operation of the system is based on the property of the brake fluid to have a very high resistance to compression. Roughly speaking, the fluid is able to transfer force from the control mechanism (pedals) to the actuator (wheel brake). The scheme of its work is simple and looks as follows.

On the left in the figure is a diagram of a conventional hydraulic brake system, on the right - brakes with ABS. In order for the replacement of brake fluid with ABS to be successful, we have a minimum of knowledge.

Proper replacement of TJ

In order for the fluid replacement procedure to be successful, it is necessary to take into account the features of the ABS device, so it is best to contact specialists. If you are still scared. If you feel strong in yourself, we will replace the liquid yourself.

At maintenance stations, masters use special devices and stands. This equipment is necessary in order for the liquid to enter the system under pressure, eliminating the chances of air entering the system and the ABS (airing) unit.

Bleeding brakes with old-style ABS

If you have a car up to the year 90, then you can safely carry out a fluid change using the method. In such vehicles, the ABS pump, hydraulic valve block and hydraulic accumulator are mounted together. Then it will be enough just to de-energize the system by removing the necessary fuse, and at the end of the work, insert it into place. When the ABS system starts, the device pump itself will pump fluid into the case, while the sound of its operation will change from high to low. This may take about a minute and after that the ignition must be turned off, since the pump without fluid can spin for no more than a few minutes.

After replacing the TJ, the entire system must be bled in the usual way. But such pumping still has a number of clarifications. When pumping those brake circuits that are directly connected to the ABS unit, the operation is carried out with the brake pedal recessed and the fittings of the working brake cylinder open. When the ignition is turned on, the pump itself removes excess air from the system and the control lamp indicating a malfunction of the ABS goes out.

Bleeding brakes with new ABS

In cars manufactured after 1990, all ABS elements are made separately from each other, which makes it necessary to apply a different fluid replacement algorithm. The operation involves accurate reading of information from each brake circuit separately and opening the fittings in a certain order. For the correct, "book" process, it is necessary to have special scanners and reading devices, which are available only at service stations.

If your car also has electronic security systems that have contact with the brakes, then the situation is even more complicated, because in order to change the fluid in such systems, you need to have very accurate computer equipment that takes into account a specific car model. Such equipment is available only at specialized services. Scary? It's OK. Now we will pump the entire system without computer equipment, which leads to a positive result in 99.9% percent.

Replacing and pumping fluid without the use of special equipment

Bleeding the brake system with ABS and replacing the fluid in it follow the same algorithm, which is described in detail below.

The operation is carried out together, and there is nothing supernatural and complicated in it. The main thing is to be careful and prevent air from entering the system through the tank. Pumping and replacing fluid is carried out in the following order:

• left front wheel;
• right front wheel;
• left rear
• right rear.

If the control lamp does not light up, then we did everything correctly and accurately. Now you can safely forget about replacing the brake fluid for the next 40-50 thousand mileage.

At the factory, the entire brake system is completely empty, but its design is such that the fluid reservoir is located on the master brake cylinder in the engine compartment, at the very top. A little lower is usually the ABS unit (who has it), and then the brake pipes go to the front and rear wheels. There, in wheel brake mechanisms, cylinders of different versions can be used. But one feature unites all of them: at the very top of the cylinder there is always a bleeder. It is also sometimes referred to as an air release valve.

Elements of the working brake system of a car with ABS: 1 - front wheel brake mechanism; 2 - tube brake mechanism of the front wheel; 3 - ABS block; 4 - hydraulic drive tank; 5 - main brake cylinder; 6 - vacuum amplifier; 7 - brake pedal; 8 - tube of the brake mechanism of the rear wheel; 9 - rear wheel brake cylinder; 10 - rear wheel brake hose; 11 - front wheel brake hose

At the factory, a special fitting is put on the neck of the tank, through which brake fluid fills the system under pressure. The worker, located below, opens the bleed fittings on the wheel cylinders in turn. Air is forced out of them first, and then brake fluid comes. All. The fitting can be turned. By repeating this operation with all the wheels of the car, we get a fully charged and efficient brake system. It remains to disconnect the filling fitting from the neck of the reservoir mounted on the main brake cylinder, and wrap the cap of the reservoir.

The question arises, can an ordinary car owner use the same method? If you've been repairing a brake system with hydraulic components replaced, or are bleeding the system because you suspect it has air in it, I usually recommend a classic pump-and-hold bleed. More intensive passage of fluid in the tubes and cavities of the cylinders is guaranteed to displace air bubbles.

Don't try this at home?

But what if we were going to, in accordance with the maintenance schedule for our car, just change the fluid? Someone every two years, someone - every three. And here the method of pouring the system with new brake fluid comes to the rescue. We use the fact that the liquid tank is located high, and the liquid simply drains down to the working cylinders under the influence of gravity. The main advantage of the proposed method is that it does not require an assistant.

Brake fluid should be purchased with a margin (at least 1 liter). It is interesting, by the way, that almost all cars, regardless of their size, cross-country ability, availability of systems and other differences, have a brake system capacity of about half a liter. Please note that the replacement takes place by mixing, so you need to spill a slightly larger amount of liquid through the system. Stock up on 1 liter of brake fluid from any manufacturer (they are all compatible). DOT-4 is the most common brake fluid used in the vast majority of vehicles. It has to be replaced due to its high hygroscopicity - the ability to absorb moisture from the air and lose its performance because of this.

So, an independent replacement of the brake fluid will require you to install the car on an inspection ditch or overpass and provide a free passage between the place where you can replenish the brake fluid reservoir in the engine compartment and the brake cylinders of all four wheels.

We work in stages

We pump out the brake fluid from the tank with a rubber bulb or syringe. Add new fluid to the top edge. To speed up the process (in order to release liquid from all cylinders at once), it is advisable to pick up four pieces of tubes that fit tightly on the bleed fittings of all cylinders. We lower the free ends of the tubes into transparent bottles of a small capacity.

We turn off the fittings of all brake cylinders. We make sure that the liquid has flowed through all four tubes. We control the decrease in fluid from the tank located on the brake cylinder, and immediately replenish the tank. We observe an increase in the level of liquid in bottles located near the wheel brake cylinders.

It is necessary several times to change the role of the observer for draining the fluid from the fittings of the brake cylinders to the role of the controller, replenishing the fluid level in the reservoir on the brake cylinder in order to prevent it from draining.

The fastest filling, as a rule, occurs in the case of a bottle into which a hose is lowered, coming from the brake cylinder of the front left wheel. As soon as there is about 200 ml of liquid in the bottle of the front left wheel, we wrap and tighten the fitting of the local cylinder. Repeat the same with the front right wheel. We complete the process on the rear axle - here 200–250 ml of liquid must pass through each fitting.

That's it, the brake fluid change is complete. It remains only to make sure that all fittings are tight. We put on protective caps, specify the fluid level in the reservoir of the main brake cylinder - and go.