14.9. Anti-lock System (ABS)

The principle of operation of the ABS anti-lock system is not considered in this manual, but it is necessary to stop at the following points:

If the car is equipped with ABS, then disk brakes are installed on the back bridge. In the POLO brand cars, this system is installed in the presence of drum brakes on the rear axle;

The decisive factor in ensuring safety during the operation of ABS is the ability to prevent wheel blocking with a sharp braking of the car, which improves handling. Even with emergency braking, it is always preserved a chance to drive around the obstacle without the danger of the rear wheels. We should not forget that ABS cannot work wonders. With too high speeds can be driven by a car and with ABS;

The four electronic sensors installed in the swivel fists and the hubs of the rear wheel constantly, independently of each other control the frequency of rotation of the toothed crowns mounted on wheels. In fig. And it is shown where sensors and gear crowns are installed. Signals from sensors come to an electronic control unit, which registers them and analyzes deviations from the norm compared to the braking program. As a result, the braking force rendered to the appropriate wheel in combination with the operation of the hydraulic system of this brake decreases or increases with a frequency of four to ten times per second, that is, much faster than this can be achieved by periodic pressing brake pedal, and in addition, brake The force is adjustable on each wheel separately, and not on all wheels simultaneously when you click on the brake pedal on vehicles without ABS;

Two hydraulic valves accurately distribute the necessary braking force between the front brakes depending on the state of the road. Two more regulating valves manage rear brakes. In this case, the electronic control unit loosens the brake force on the wheel, which is blocked first. With an optimal braking coefficient, the car remains controlled, its stability and control over the situation are preserved.

Since the ABS system should provide additional security, it is not recommended to carry out any work on it, despite the fact that some of them are easy to perform. Nevertheless, when performing some works on the brake system with ABS, the following requirements must be followed:

Before disassembling, carefully clean all the connections and the elements of the equipment directly adjacent to them;

The surface where the removed parts are placed, should be clean. Details should be covered with film or pure paper. Do not use a rags for this;

Carefully close the open parts of the system or close them if the repair can not be started immediately. This applies especially to the cases when the car has to put on the open parking lot;

Installing only absolutely clean details. In no case to install the details that were held for a long time in storage;

If there are air compressors, there is always a temptation to use compressed air for cleaning parts. In no case cannot do this if the system connections are open.

After turning on the ignition, the hydraulic pump for 60 s creates the operating pressure in the system. The ABS signal lamp lights up at 2 to 20 s, depending on the pressure in the system. The electronic control unit starts checking the operation of all system components. When any faults are detected, the brake system works as a regular system without ABS. If this happens (the ABS warning lamp continues to burn), then you should contact the car service where the malfunction in the system can be determined using special devices, which can be associated with failures in electrical equipment or in the hydraulic circuit of the system.

Anti-lock brake system (ABS) consists of wheel speed sensors, switch on the main brake cylinder, hydroelectronic control module and signal lamp in the instrument combination. In the variant design, the anti-lock blocking system can additionally be equipped with a course stability system that ensures the preservation of rectilinear movement with poor road conditions by braking this or other wheel (ESP), as well as a self-diagnosis system that detects the problems of the system components.

ABS serves to regulate the pressure in the brake mechanisms of all wheels when braking in complex road conditions and thereby prevents the wheel lock.

The ABS system provides the following advantages:

Detour obstacles with a higher degree of safety, including in emergency braking;

Reducing the brake path with emergency braking while maintaining coursework stability and car handling, including in turn.

In the event of a malfunction of the system, diagnostic functions and maintenance of operation at system failures are provided.

The hydroelectron control module receives information about the velocity of the vehicle, the direction of movement and road conditions from the wheel speed sensors, the steering electrical power control unit, the throttle position sensor. After turning on the ignition, the control unit gives a voltage to the rotational speed sensors in which the Hall effect is used. Sensors generate an output signal in the form of rectangular pulses. The signal changes in proportion to the frequency of rotation of the name pool of the sensor vehicle.

Based on this information, the control unit determines the optimal braking mode of the wheels.

Distinguish the following modes of operation of the anti-lock system:

Mode of normal braking. With normal braking inlet valve open. The outlet valve is closed. When the brake pedal is pressed, the brake fluid under pressure is supplied to the working cylinder and drives the brake mechanisms of the wheels. When the brake pedal is released, the brake fluid returns to the main brake cylinder through the inlet and check valves;

Emergency braking mode. If the wheel lock begins during emergency braking, the module displays the command to a decrease in the supply of brake fluid to the pump electric motor, then the voltage is fed to each solenoid valve. The intake valve is closed and the supply of brake fluid from the main cylinder and the pump is overlapped; The outlet valve opens, and the brake fluid comes from the working cylinder to the main, and then to the tank, which causes a pressure reduction;

Pressure maintenance mode. With a maximum pressure reduction in the working cylinder, the module issues a command to maintain the pressure of the brake fluid, the voltage is fed to the intake valve and is not fed to the exhaust valve. At the same time, the inlet and exhaust valve closed and the brake fluid from the working cylinder does not go away;

Pressure increase mode. If the module determines that the wheel is not blocked, the voltage to the solenoid valves is not supplied, the brake fluid through the input valve enters the working cylinder, the pressure in which increases.

To diagnose and repair anti-lock brakes, special equipment and equipment are required, so if it is out of order, contact a specialized maintenance station.

This subsection describes only the replacement of the rotational speed sensors and the hydroelectron block. However, keep in mind that to remove air, which can at all in the system of valves of the hydroelectron block with unqualified removal, requires special equipment. Therefore, we do not recommend removing the unit without an extreme need, and to replace the block should be referred to service.

Removal and installation of the hydroelectron control unit of the anti-lock brake system

You will need: the end head "at 12", the special key "at 11" for brake pipelines.

2. Press down the stopper locking bracket ...

3. ... Lower the bracket down.

4. ... Disconnect the block from the hydropower control unit of the anti-lock brake system.

5. Loosen the tightening of nuts of six hydraulic tubes. attached to the hydropower unit

6. Unscrew the three nuts for fastening the hydroelectronic block to the body bracket.

7. Alternately, disconnect the hydraulic system from the tube block, immediately drowning the holes in the package of pre-harvested plugs (wooden or rubber) suitable size, and remove the block by lifting it up.

After removing, do not turn over and do not tilt a strongly hydroelectron block: if when removing the block, to allow complete leakage of the brake fluid from its cavities, after installing the unit, the air can be removed using a special tester. In the usual way (using brake pedal), remove air from the system will not be possible.

8. Install the hydroelectron control of the anti-lock brake system and all removed parts are in order to remove.

9. Remove the air from the brake hydraulic

Removing and installing wheel speed sensors

You will need: Hex key<на 5», отвертка с плоским лезвием.

Work on the replacement of wheel speed sensors is more convenient to perform on the lift. The replacement of the rotational speed sensors of the left front and left rear wheel is shown. Right front and right rear wheel speed sensors are replaced similarly.
Front wheel speed sensor is installed in the front suspension rotary fist. To replace it, perform the following operations.

1. Disconnect the wire from the minus terminal of the battery.

2. Remove the front wheel.

3. Press the lock of the front wheel speed of the front wheel rotation sensor wiring shoes and disconnect the shoe from the sensor.

4. Remove the sensor fastening bolt to a twilty fist

5. ... And remove the sensor out of the fist.

6. Install the front wheel speed sensor in the reverse order.

Rear wheel speed sensor is installed in the rear suspension lever flange hole. To replace it, perform the following operations.

1. Disconnect the wire from the minus terminal of the battery.

2. Remove the rear wheel.

3. Remove the rear wheel liner

4. Remove the bottom facing of the rear body rack

5. In the car's cabin, click the lock of the rear wheel speed of the rear wheel speed sensor and disconnect the sensor block from the transition pad.

6. Remove the rear wheel speed sensor holder from the groove in the body bracket.

7. Push the sensor wire seal into the body opening.

8. Remove the rotational speed sensor bolt to the flange of the rear suspension lever ...

9. ... And remove the sensor from the flange hole.

10. Display the sensor wire bush from the slot of the longitudinal lever bracket.

11. Similarly, remove the sleeves of the sensor wires from the bodies of the body brackets ..

12. ... and remove the sensor, pulling the shutter of the sensor with the body opening.

13. Install the reverse wheel speed sensor and all parts in the reverse order.

Replacing faulty electronics or ABS sensor, wiring recovery or installing a new specifying disk is not a problem for an experienced specialist "armed" scanner, tester and high-quality tool. By contacting the car service of our network, you are guaranteed to get rid of failures in the work of the anti-lock system and you will be confident in the reliability of the brakes of your Volkswagen Polo.

Malfunctions and symptoms

In case of failures in the work or refusal of the anti-lock system, the corresponding control lamp lights up on the folkwagen dashboard. In this case, you can continue to move, but to slow down with caution to prevent blocking wheels and driving a car. The main causes of breakage are faults of wheel sensors, wiring or control electronics. Quickly and unmistakably determine the faulty node can only with the help of diagnostic equipment.

The cause of the ABS sensor failure can be:

• wheel rotation speed sensor breakdown,
• break or bad contact in its wiring,
• damage to the specifying disk,
• incorrect installation of new parts (the gap between the disk and the sensor should not exceed 0.3..0.5 mm).

There is a sedan polo and "branded disease" - damage to the insulation of the central wire of the ABS block. To prevent closure or cliff, it must be strengthened.

Order of work

In addition to the sensors, the system can exit both hydraulics and an electrician of the central unit. In most cases, repairing this node is inappropriate, as it will not be possible to guarantee its stable and reliable operation. Therefore, the performance of the system is restored only by installing and coding a new brain.

ABS failure diagnostics

The driver's ABS failures notify a special test lamp located on the instrument shield of the car. As soon as the ABS control module detects the fact of violations in the system, it produces its disconnection. The brake system continues to function as usual.

The ABS status diagnostics is performed each time when the engine is started and is accompanied by a short-term triggering of the control lamp. For a short time after launching Lama should automatically turn off.

If the ABS control lamp lights up and continues to burn while driving, first make sure that the parking brake is completely released, and the braking system operates properly. If everything is normal, therefore, ABS fails. First, make the following simple checks:

a) Check the condition of brake calipers and wheeled cylinders;
b) Check the condition and reliability of fastening the contact connectors of the ABS control module and wheel sensors (see chapter Side electrical equipment);
c) Check the appropriate fuses (see chapter Side electrical equipment).

ABS control lamp failures

The reason for the failure of the ABS control lamp function may be a break or short circuit in the circuit of its electrical wiring.

The ABS control lamp is not activated when the ignition is turned on


Try to turn on the ignition without making the engine start, if other, included in the device combination, the control lamps work properly, go to the next check step, otherwise you should produce the required dashboard remediation.

Turn off the ignition. Remove the instrument combination, remove the ABS control lamp and check its condition. If the lamp burned, make it a replacement, otherwise go to the next check step.

Discover the contact pair of B62 / F45 and measure the voltage between the chassis (-) and terminal No. G6 (+) B62 connector. If the measurement result is less than 3 V, go to the next check step, otherwise, check the state of the electrical wiring of the corresponding control lamp. Make the necessary recovery repair.

Turn off the ignition, set the test warning lamp to your regular place and set the instrument combination.

Turn on the ignition and repeat the voltage measurement. If the measurement result does not go beyond the range of 10 ÷ 15 V, go to the next check step, otherwise check the wiring condition. Make the necessary recovery repair.

Turn off the ignition and check the voltage between the terminal G6 (+) F45 connector and the chassis mass. If the measurement result is less than 3 V, go to the next check step, otherwise check the state of the corresponding wiring. Make the necessary recovery repair.

Turn on the ignition and repeat the check. If the measurement result is less than 3 V, go to the next check step, otherwise, check the state of the electrical wiring of the corresponding control lamp. Make the necessary recovery repair.

Measure the resistance between terminal No. 23 F49 connector and mass. If the measurement result is less than 5 ohms, go to the next check step, otherwise check the health of the control / hydrojulator assembly assembly. Make the necessary recovery repair.

Measure the resistance between the mass and terminal G6 connector F45. If the measurement result is less than 5 ohms, go to the next check step, otherwise check the status of the connector and the harness of its electrical wiring. Make the necessary recovery repair, if necessary, replace the connector.

Turn off the ignition and check the correctness of the status of the contact connectors on the chain area between the instrument combination and the ABS control module, if there are no signs of the contact reliability, replace the ABS control module assembly.

The ABS warning lamp is not turned off after the engine start


Turn off the ignition and make sure that the contact connector of the control module / Hydromodulator ABS is complete and secured.

Measure the resistance between the mass of the chassis and each (A and B) from the diagnostic terminals (B81). If the measurement result is less than 5 ohms, go to the next check step, otherwise check the state of the harness of the corresponding wiring, make the necessary recovery repair.

Turn off the ignition and connect the diagnostic terminal to terminal No. 8 of the B82 diagnostic connector. Disconnect the ABS control module pin connector and measure the resistance between the F49 connector terminal and the chassis mass. If the measurement result is less than 5 ohms, go to the next check step, otherwise check the wiring status on the chain area between the ABS control module and the diagnostic connector, make the necessary restoration repair.

Run the engine at idle and check the voltage between the terminal in (+) on the rear side of the generator (power terminal) and the chassis mass. If the measurement result does not go beyond the range of 10 ÷ 15 V, go to the next check step, otherwise replace / repaired the generator (see chapter) and repeat the scan.

Turn off the ignition and check the condition of the Pole terminals of the battery and the reliability of the terminal tips on them. If necessary, make the necessary corrections.

Disconnect the ABS control module electrical wiring connector, then run the engine at idle and measure the voltage between the F49 connector and the chassis slot. If the measurement result does not go beyond the range of 10 ÷ 15 V, go to the next check step, otherwise check the power of the power supply circuit. Make the necessary recovery repair.

Dispature the contact pair of B62 / F45 and turn on the ignition - if the ABS control lamp does not work, go to the next check step, otherwise check the condition of the front wiring harness.

Turn off the ignition and check the status of the protrusions of the control module connector. If the terminals are in order, go to the next check step, otherwise replace the control module / hydraulicodulator (see section).

Measure the resistance between terminals No. 22 and 23 of the ABS control module connector. If the measurement result is more than 1 mΩ, go to the next check step, otherwise replace the ABS control / hydrojulator assembly (see section. Removing, installing and checking the functioning of the control of the control module / hydrojulator ABS).

Measure the resistance between the F45 slot G6 terminal and the chassis mass. If the measurement result is less than 0.5 ohms, go to the next check step, otherwise, make the required wire repair.

Connect the electrical wiring to the ABS control module and measure the resistance between the F45 Connector G6 and the chassis mass. If the measurement result is more than 1 mΩ, go to the next check step, otherwise, make the necessary recovery repair of electrical wiring.

Check the status and reliability of the ABS Control Connector Contact Connector. If necessary, make the necessary corrections, or replace the control unit / hydraulic module unit.

Could not read the fault codes

If the test lamp turns on and turns off properly, but does not highlight the initial code (DTC 11, see below) when switching to the diagnostic mode, turn off the ignition and check.

Wheel sensor failures

Wheel sensor failures lead to a malfunction of the operation of ABS. Connection diagram of wheel sensors is presented in illustration.

Disconnect the wiring from the ABS control module and measure the voltage between the terminal number 1 of the corresponding wheel sensor and the chassis mass. If the measurement result is less than 1 B, proceed to the next check step, otherwise replace the sensor.

Turn on the ignition and repeat the previous check. If the measurement result is less than 1 B, proceed to the next check step, otherwise replace the sensor.

Turn off the ignition and connect the wiring to the sensor. Measure the resistance between terminals No. 11 and 12 (DTC 21) / 9 and 10 (DTC 23) / 14 and 15 (DTC 25) / 7 and 8 (DTC 27) F49 connector. If the measurement result does not go beyond the range of 1 ÷ 1.5 kΩ, go to the next check step, otherwise check the wiring status on the site between the control module and the sensor. Make the necessary recovery repair.

Measure the voltage between mass and terminal No. 11 (DTC 21) / 9 (DTC 23) / 14 (DTC 25) / 7 (DTC 27) of the F49 connector. If the measurement result is more than 1 B, eliminate the cause of the short circuit on the circuit area between the sensor and the ABS control module. In the absence of voltage (less than 1 V), turn on the ignition and repeat the check. If the voltage is still missing (it is less than 1 c), go to the next check step, otherwise check the wiring status between the sensor and the ABS control module, if necessary, eliminate the cause of the short circuit.

Measure the size of the gap between the sensor and the rotor throughout the perimeter of the latter. With insufficient gap (see Specifications) Make it adjust it by selecting the adjustment gasket (26755AA000). If the clearance is too large, remove the remote gaskets and replace the rotor (assembled with the hinge assembly) or the sensor failed. Having finished adjustment, go to the next check step.

Turn off the ignition and measure the resistance between the terminal No. 1 of the contact connector of the wheel sensor and the mass of the chassis. If the measurement result is more than 1 mΩ, proceed to the next check step, otherwise replace the sensor.

Turn off the ignition and connect the wiring to the wheel sensor. Measure the resistance between the chassis mass and terminal No. 11 (DLC 21) / 9 (DLC 23) / 14 (DLC 25) / 7 (DLC 27) of the F49 connector. If the measurement result is more than 1 mΩ, go to the next check step, otherwise check the wiring status on the chain area between the sensor and the ABS control module. Make the necessary recovery repair. If the wiring is in order, replace the control of the control / hydrojulator module.

Restore the original connection of all contact connectors, clean the processor memory (see below) and repeat the reading procedure of diagnostic codes. If no changes (in the direction of improvement) did not occur, replace the ABS control module assembly / Hydromodulator. When new codes appear, go to the appropriate check. If the failure never happened, therefore, the malfunction was temporary, - once again make sure the reliability of fixing all contact compounds.

Short circuit in the chain of the wheel sensor (DTC Nos. 22, 24, 26 and 28)

Turn off the ignition and check the reliability of the sensor fastening bolts (32 nm). If necessary, pull the fastener and go to the next check step.

In the absence of an opportunity to use the oscilloscope, proceed to check the mechanical state of the rotor and cleaning components.

In the presence of an oscilloscope, subdominate the car and install it on the backups - the wheels must completely break away from the ground. Turn off the ignition and connect the oscilloscope between the terminals No. C5 (+) and B5 (-) (DTC 22) / C6 (+) and B6 (-) (DTC 24) connector B62 or 1 (+) and 2 (-) (DTC 26) / 4 (+) and 5 (-) (DTC 28) F55 connector.

Turn on the ignition and rotating the appropriate wheel of the car, follow the oscilloscope testimony. The amplitude of the sinusoidal signal displayed on the screen should not go beyond the range of 0.12 ÷ 1.00 V, - if this condition is not performed, or the signal has an incorrect form, go to the next check step.

Check the wheel of the wheel hub. If the measurement result is less than 0.05 mm, go to the next check step, otherwise replace the hub.

Turn off the ignition. Disconnect the wiring from the appropriate wheel sensor. Measure the resistance between the terminals number 1 and 2 of the sensor connector. If the measurement result does not go beyond the range of 1 ÷ 1.5 com, proceed to the next check step, otherwise replace the sensor.

Measure the resistance between mass and terminal No. 1 of the contact connector of the wheel sensor. If the measurement result is more than 1 mΩ, proceed to the next check step, otherwise replace the sensor.

Connect the wiring to the wheel sensor and disconnect it from the ABS control module. Measure the resistance between terminals No. 11 and 12 (DTC 22) / 9 and 10 (DTC 24) / 14 and 15 (DTC 26) / 7 and 8 (DTC 28) of the ABS control module F49 connector. If the measurement result does not go beyond the range of 1 ÷ 1.5 kΩ, go to the next check step, otherwise, make the necessary wire repair on the circuit area between the sensor and the ABS Hydromodulator Module.

Measure the resistance between the chassis mass and terminal No. 11 (DTC 22) / 9 (DTC 24) / 14 (DTC 26) / 7 (DTC 28) of the Control Module F49 connector. If the measurement result is more than 1 mΩ, go to the next check step, otherwise, check the wiring between the sensor and the module for the presence of a short circuit. Make the necessary recovery repair.

Measure the resistance between mass and terminal No. 23 of the F49 connector. If the measurement result is less than 0.5 ohms, go to the next check step, otherwise eliminate the cause of the grounding quality.

Check the reliability of the attachment of the contact connections of the ABS control module and the wheel sensor. Make the necessary corrections. If contacts are in order, go to the next check step.

Make sure that the car telephone / transmitter of the remote control is mounted on a sufficient distance from the wiring wiring harness.

Restore the original connection of all contact connectors and measure the resistance between mass and terminal No. A5 (DTC 22) / A6 (DTC 24) B62 connector. If the measurement result is less than 0.5 ohms, go to the next check step, otherwise replace the shielded harness.

Restore the original connection of all contact connectors and repeat the reading procedure of diagnostic codes. If no changes (in the direction of improvement) did not occur, replace the ABS control module assembly / Hydromodulator. When new codes appear, go to the appropriate test. If the failure never happened, therefore, the malfunction was temporary, - once again make sure the reliability of fixing all contact compounds.

There are problems associated with the serviceability of the wheel sensor (one or all four) of the information signal (DTC 29)


Evaluate the status of the protector and pumping tires. If necessary, make appropriate fixes / replacements.

Check the reliability of the ABS sensor fastening bolts (32 nm). If necessary, pull the fastener and go to the next check step.

Measure the size of the gap between the sensor and the rotor throughout the perimeter of the latter. With an insufficient gap (see Specifications), make it adjustment by selecting the adjustment gasket (26755AA000). If the clearance is too large, remove the remote gaskets and replace the rotor (assembled with the hinge assembly) or the sensor failed. Having finished adjustment, go to the next check step.

In the absence of an opportunity to use the oscilloscope, proceed to check the mechanical state of the rotor and cleaning components. In the presence of an oscilloscope, subdominate the car and install it on the backups - the wheels must completely break away from the ground. Turn off the ignition and connect the oscilloscope between the terminals No. C5 (+) and B5 (-) (DTC 22) / C6 (+) and B6 (-) (DTC 24) connector B62 or 1 (+) and 2 (-) (DTC 26) / 4 (+) and 5 (-) (DTC 28) F55 connector.

Turn on the ignition and rotating the appropriate wheel of the car, follow the oscilloscope testimony. The amplitude of the sinusoidal signal displayed should not go beyond the range of 0.12 ÷ 1.00 V, - if this condition is not executed, or the signal has an incorrect form, go to the next check step, otherwise go to the following check.

Carefully inspect the wheel sensor and its rotor for signs of damage and contamination. Wipe the components, eliminate the problem.

Check the wheel of the wheel hub. If the measurement result is less than 0.05 mm, go to the next check step, otherwise replace the hub.

Turn off the ignition. Restore the initial connection of the wiring. Clean the processor memory (see below) and repeat the reading procedure of diagnostic codes. If no changes (in the direction of improvement) did not occur, replace the ABS control module assembly / Hydromodulator. When new codes appear, go to the appropriate test. If the failure never happened, therefore, the malfunction was temporary, - once again check the reliability of fixing all contact compounds.

Refusals of the control module / ABS hydrojulator


Violation of the functioning of the intake (DTC 31, 33, 35 and 37) / graduation (DTC 32, 34, 36 and 38) of the solenoid valve

Disconnect the wiring from the ABS control module.

Run the engine to idle and measure the voltage between the F49 control unit and the chassis block. If the measurement result does not go beyond the range of 10 ÷ 15 V, go to the next check step, otherwise check the wiring status between the battery, the ignition switch and the ABS control module. Make the necessary recovery repair.

Turn off the ignition and measure the resistance between the chassis mass and terminal No. 23 of the F49 connector. If the measurement result is less than 0.5 ohms, go to the next check step, otherwise eliminate the cause of the grounding quality.

Violation of the functioning of the ABS management module (DTC 41)

Turn off the ignition. Disconnect the electrical wiring from the ABS control module and measure the resistance between the F49 connector terminal number 23 and the chassis mass. If the measurement result is less than 0.5 ohms, go to the next check step, otherwise eliminate the cause of the grounding quality.

Check out the condition of the state and the reliability of fixing the electrical wiring connectors on the ABS control module, generator and battery. If necessary, make the appropriate recovery. If there are no contact quality violations, go to the next check step.

Make sure the remote control phone / transmitter is installed on sufficient removal from the ABS wiring harnesses.

Turn off the ignition. Restore the initial connection of the wiring. Clean the processor memory and repeat the reading procedure of diagnostic codes. If no changes (in the direction of improvement) did not occur, replace the ABS control module assembly / Hydromodulator. When new codes appear, go to the appropriate test. If the failure never happened, therefore, the malfunction was temporary, - once again make sure the reliability of fixing all contact compounds.

Deviation from the nominal supply voltage level (DTC 42)

Run the engine and warm it up to normal operating temperature. Check that idle speed is correct. Measure the voltage between the terminal in the (+) on the back of the generator and the mass of the chassis. If the measurement result does not go beyond the range of 10 ÷ 17 V, go to the next check step, otherwise check the state of the charge system (see chapter Electrical engine equipment ), make the necessary corrections.

Turn off the ignition and check the condition of the pole terminals of the battery and the reliability of fixing the terminal tips on them. If necessary, clean the contact surfaces of the terminals / tips. If the terminals are in order, disconnect the electrical wiring from the ABS control module, start the engine to idle and measure the voltage between the mass and terminal No. 1 (+) of the F49 connector. If the measurement result does not go beyond the range of 10 ÷ 17 V, go to the next check step, otherwise check the wiring status between the ignition switch and the ABS control module contact connector. Make the necessary recovery repair.

Turn off the ignition and measure the resistance between the F49 terminal number 23 and the chassis mass. If the measurement result is less than 0.5 ohms, go to the next check step, otherwise eliminate the cause of the grounding quality.

Check the condition of the status and reliability of fixing the electrical wiring connectors on the ABS control module, generator and battery. If necessary, make the appropriate recovery. If there are no contact quality violations, go to the next check step.

Turn off the ignition. Restore the initial connection of the wiring. Clean the processor memory and repeat the reading procedure of diagnostic codes. If no changes (in the direction of improvement) did not occur, replace the ABS control module assembly / Hydromodulator. When new codes appear, go to the appropriate test. If the failure never happened, therefore, the malfunction was temporary, - once again make sure the reliability of fixing all contact compounds.

Violation of the functioning of the AT control system (DTC 44)

Turn off the ignition and disconnect the two transmission control module electrical wiring connections (TCM). Also disconnect the wiring from the ABS control module. Measure the resistance between terminal No. 3 F49 connector and chassis mass. If the measurement result is more than 1 mΩ, go to the next check step, otherwise, make the electrical wiring repair on the TCM site and the ABS control module.

Turn on the ignition and measure the voltage between the mass and terminal number 3 of the F49 connector. If the measurement result is less than 1 V, go to the next check step, otherwise, make the required wire repair on the site between the TCM and the ABS control module.

Measure the voltage between mass and terminals No. 3 and 31 of the F49 connector. If the measurement result does not go beyond the range of 10 ÷ 15 V, go to the next check step, otherwise check the wiring status on the site between the ABS and TCM control module. Make the necessary recovery repair.

Check the condition and reliability of fixing the contact connectors of the ABS and AT control modules. If necessary, clean the terminals and go to the next stage of verification.

Turn off the ignition. Restore the initial connection of the wiring. Clean the processor memory and repeat the reading procedure of diagnostic codes. If no changes (in the direction of improvement) did not occur, replace the ABS control module assembly / Hydromodulator. When new codes appear, go to the appropriate test. If the failure never happened, therefore, the malfunction was temporary, - once again make sure the reliability of fixing all contact compounds.

Violation of the functioning of the valve relay (DTC 51)

Turn off the ignition and disconnect the wiring from the ABS control unit. Run the engine at idle and measure the voltage between the terminals No. 1 and 24 of the ABS control module and the chassis module. If the measurement result does not go beyond the range of 10 ÷ 15 V, go to the next check step, otherwise check the wiring status between the ABS control unit and the battery. Make the necessary recovery repair.

Measure the resistance between terminals No. 23 (+) and 24 (-) connector of the control module. If the measurement result is more than 1 mΩ, go to the next check step, otherwise replace the control unit.

Check out the condition of the state and the reliability of fixing the electrical wiring connectors on the ABS control module, generator and battery. If necessary, make the appropriate recovery. If there is no violation of the quality of contacts, go to the next check step.

Turn off the ignition. Restore the initial connection of the wiring. Clean the processor memory and repeat the reading procedure of diagnostic codes. If no changes (in the direction of improvement) did not occur, replace the ABS control module assembly / Hydromodulator. When new codes appear, go to the appropriate test. If the failure never happened, therefore, the malfunction was temporary, - once again make sure the reliability of fixing all contact compounds.

Violation of the function of functioning of the drive electro-vehicle / its relay (DTC 52)

Turn off the ignition. Disconnect the electrical wiring from the ABS control module, then turn the ignition key to the ON position and measure the voltage between the control and chassis module and the chassis terminal. If the measurement result does not go beyond the range of 10 ÷ 15 V, go to the next check step, otherwise, make the electrical wiring repair on the site between the battery and the control / hydraulic module module. Check the SBF-holder of the fuse.

Turn off the ignition and measure the resistance between mass and terminal No. 26 of the F49 connector. If the measurement result is less than 0.5 ohms, proceed to the next check step, otherwise, make a refurbishment of the control circuit of the control unit.

Run the engine at idle and measure the voltage between the F49 connector terminal number 1 and the chassis mass. If the measurement result does not go beyond the range of 10 ÷ 15 V, go to the next check step, otherwise check the wiring status on the sections between the battery, the ignition switch and the ABS control module. Make the necessary recovery repair.

Turn off the ignition and measure the resistance between the mass and terminal number 23 of the F49 connector. If the measurement result is less than 0.5 ohms, go to the next check step, otherwise eliminate the cause of the grounding quality.

During the verification of the sequence of triggering valves of the hydromodulator (see section ABS Hydromodulator Valve Speed \u200b\u200bChecking) For hearing, check the operation of the electric motor. If the motor rotates properly, go to the next check step, otherwise replace the ABS control unit / block assembly.

Check the condition of the status and reliability of fixing the electrical wiring connectors on the assembly of the ABS control module / hydrojulator, the generator and the battery. If necessary, make the appropriate recovery. If there are no contact quality violations, go to the next check step.

Turn off the ignition. Restore the initial connection of the wiring. Clean the processor memory and repeat the reading procedure of diagnostic codes. If no changes (in the direction of improvement) did not occur, replace the ABS control module assembly / Hydromodulator. When new codes appear, go to the appropriate test. If the failure never happened, therefore, the malfunction was temporary, - once again make sure the reliability of fixing all contact compounds.

Violation of the functioning of the stop signals switching switch (DTC 54)

Failure of the stop signal switch leads to a malfunction of the operation of ABS.

Check out the serviceability of stop signals when squeezing the foot brake pedal. If everything is in order, go to the next check step, otherwise check the status of the lamps and electrical wiring chains of the stop signals.

Turn off the ignition. Disconnect the wiring from the ABS control module. Sick the foot brake pedal and measure the voltage between the ABS control module Module F49 and the chassis module. If the measurement result does not go beyond the range of 10 ÷ 15 V, go to the next check step, otherwise check the wiring status on the site between the stop signals sensor and the ABS control module. Make the necessary recovery repair.

Check the condition and reliability of fixing the contact switch connector and the control unit. If necessary, make appropriate corrections. If contacts are in order, go to the next check step.

Violation of the health of the output signal of the G-sensor (DTC 56)


Check the ABS control module assembly assembly: the code is applied to the block surface between the hydraulic lines connecting fittings and for models (see specifications). If the marking meets the configuration of your car, go to the next check step, otherwise replace the ABS control / hydrojulator assembly.

Disconnect the wiring from the G-sensor. Measure the resistance between the F49 connector terminal number 6 and the chassis mass. If the measurement result is more than 1 mΩ, go to the next check step, otherwise, make the required wire repair repair on the site between the sensor and the ABS control module.

Measure the voltage between the F49 terminal number 6 and the chassis mass. If the measurement result is less than 1 B, proceed to the next check step, otherwise, make the required wire repair on the site between the sensor and the ABS control module.

Repeat the last check when the ignition is on. If the measurement result is less than 1 B, go to the next check step, otherwise, make the necessary wire repair repair on the site between the sensor and the ABS module.

Measure the resistance between mass and terminal No. 28 of the F49 connector. If the measurement result is more than 1 mΩ, go to the next check step, otherwise, make the required wire repair repair on the site between the sensor and the ABS control module. If the wiring is in order, replace the assembly of the control module / hydraulic modulator.

Turn off the ignition and without disconnecting the wiring, damp the G-sensor. Check the reliability of fixing the contact slots of the sensor and the ABS control module. Turn on the ignition and measure the voltage between the terminals No. 2 (+) and No. 3 (-) of the sensor R70 connector. If the measurement result does not go beyond the range of 2.1 ÷ 2.4 V, go to the next check step, otherwise replace the sensor.

Tilt the sensor at an angle of 90 ° forward and repeat the verification described above. If the measurement result does not go beyond the range of 3.7 ÷ 4.1 B, go to the next check step, otherwise replace the sensor.

Tilt the sensor at an angle of 90 ° and still repeat the check. If the measurement result does not go beyond the range of 0.5 ÷ 0.9 V, go to the next check step, otherwise replace the sensor.

Turn off the ignition. Check the condition and reliability of fixing the contact connectors of the G-sensor and the ABS module. If necessary, make the appropriate recovery. If the contact connections are in order, go to the next check step.

Restore the initial connection of the wiring. Clean the processor memory and repeat the reading procedure of diagnostic codes. If no changes (in the direction of improvement) did not occur, replace the ABS control module assembly / Hydromodulator. When new codes appear, go to the appropriate test. If the failure never happened, therefore, the malfunction was temporary, - once again make sure the reliability of fixing all contact compounds.

Checking the ABS Management Module I / Input Signals

The location map of the contact terminals in the control / hydrojulator module connector and the electrical connections of the ABS components are shown in the illustrations.

ABS electrical connections diagram

Connect to SSM diagnostic cable and fill the cartridge.

Connect the SSM diagnostic cable to the DLC connector located on the left under the car instrument panel.

Turn the ignition key to the ON position (Do not start the engine) and turn on the SSM power.

In the main menu ("Main Menu") of the reader screen, select Section (Each System Check) and press the YES key.

In the System Selection Menu field, select the screen (Brake Control System), confirm the selection by clicking on the YES key.

After displaying information about the ABS type, again, press the YES key.

In the "ABS Diagnosis" field, select (Diagnostic Code (s) Display) and confirm the selection by pressing the YES key.

In the Diagnostic Code (s) section of the screen, select (Current Diagnostic Code (S)) (Current Code) or (History Diagnostic Code (s)), press the YES key.

Read current data

Enter the Menu subsection (Brake Control System), wait for the ABS Type message to the screen and press the YES key.

In the "Brake Control Diagnosis" field, select the (Current Data Display & Save) and confirm the selection by clicking on the YES key.

In the Data Select Menu field, select (Data Display) and click Yes.

Using the scroll buttons, moving on the displayed list, select the data you are interested in. The list of output data is given in the table below.

Turn off the ignition and connect the diagnostic terminal to terminal number 8 of the connector.

Turn on the ignition, the ABS control lamp will switch to the diagnostic mode and starts in flashing the fault codes (DTC) in flashing processor.

The first is always displayed the test code (11), then all other codes are displayed alternately, starting with the latter. After the latter code is output, the cycle is repeated for 3 minutes. Examples of codes are shown in the illustration. In the absence of recorded codes, the test lamp will display only the starting code (11).

In the "System Select Menu" field, select (Brake System), click Yes, wait for the ABS type information on the screen, then press the YES key again.

In the "Brake Control Diagnosis" field, select the (Clear Memory) screen and confirm the selection by clicking on the YES key.

After the "Done" messages and Turn Ignition Off (turn off the ignition) are displayed on the reader's screen, turn off the SSM power and turn off the ignition.

Without use SSM

For about 12 seconds, we repeat the procedure for connecting / disconnecting the terminal with a duration of each phase (on and off) at least 0.2 s.

Successful completion of memory cleaning is confirmed by flashing the control lamp 11.

Anti-lock system (ABS) is an electronic assistant, which is installed in almost all modern cars. The essence of the system is that it prevents blocking the wheels with strong braking and at the same time distributes the braking force. An anti-lock system allows you to:

• Safely make maneuvers;
• Exclude a car drift;
• Effectively slow down the car when pressed until the brake pedal stops.

ABS system device

At one of the most demanded budget car - Volkswagen Polo Sedan is equipped with an ABS unit operating on the hydromodule. This allows you to increase comfort and safety when driving, and also significantly simplified the device that is completed with the following components:

• Rotation frequency sensors;
• The relay of the main brake mechanism;
• Gyroelectron block.

After turning the key to the "Ignition" mode on the dashboard, the control light is required to light up, and if it went out a few seconds, this indicates the health of the ABS system.

For reference! In some cars, the Volkswagen Polo is available to the ECP system - a course stability system that helps more effectively maintain car stability on the road during emergency braking!

In addition, the parting computer polo includes a self-diagnostic system that detects malfunctions of all electronic systems. For example, if the ABS indicator caught fire on the dashboard, this may indicate damage to the wire of one of the sensors or increased wear of the tires.

The cost of all elements of the ABS system is given in the following table:

The principle of operation of the ABS system

The principle of operation of this system is based on the fact that the steering electric power switch in conjunction with the throttle sensor transmits the necessary information to the rotational speed sensors and the hydropower module in the form of pulses. As soon as the driver turns on the ignition, the voltage is immediately transmitted to the sensors forming special signals by which the ABS block selects the optimal brake mode.


It is worth noting that during slowing down the hydroelectron block is almost not activated. The vehicle stop is carried out by the standard method: the brake systems are powered by brake fluid, which falls into working cylinders. If you remove the leg from the brake pedal, the liquid is sent in the brake cylinder.

Emergency braking of the car is otherwise performed. At the same time, a whole system is activated: the ABS control unit transmits information on reducing the amount of fluid supplied to the working cylinder, in parallel with this, the inlet valves overlap and the opening of the graduation occurs. All this leads to a decrease in pressure in the brake system. After that, the pressure in the working brake cylinder is optimized and keeps at this level until braking is completed. If the driver completely stops harvesting on the brake pedal, the fluid enters the working cylinder, which leads to a decrease in pressure.

Disadvantages of ABS Systems

Many inexperienced drivers are wondering why some drivers turn off the ABS system if it is so effective? ". There are four main points, due to which many drivers against the electronic assistant:

1. During emergency braking, the car stop does not carry out the driver, but the ABS system. Therefore, in what place the car will stop its movement, unknown;
2. In the work of the electronic program there may be delays in analyzing the information on the condition of the road surface;
3. An inhomogeneous road canvas may not affect the braking of the car. With a slight turn of the steering wheel with a large share of probability, the car will go to the SMA;
4. The elements of the ABS system can easily be damaged by small stones, which are very often found on our roads. The output of the ABS system is made guaranteed to cause stress at the driver;
5. The ABS system is completely disconnected if the vehicle speed is less than 10 km / h. At this speed, the driver is least awaiting danger, however, in this situation the wheels can be blocked.

How to disable ABS system

In order to disable the ABS system you just need to get to the fuse block. In the Volkswagen Polo car there are two of them. The first is located in the pumproom and the ABS system there are two fuses there - according to the number "4" at 10 A and SA5 on 25 A. in order to disable them, it is necessary to disconnect the terminals from them. The second safety unit is located in the car, under the steer. In it for abs responds "9" number.