Anti-lock brakes with electronic differential blocker (EDS)

Some cars VW Passat in addition to the ABS system can be equipped with electronic differential lock (EDS). As an extra to the system ABS, EDS system reduces the transfer of engine torque under adverse driving conditions, especially on the climbs and acceleration of the vehicle by eliminating one slip of the drive wheels, as well as starting and acceleration. Thanks to the electronic differential lock is achieved by improving the transmission of torque, as this party with a higher coefficient of friction can transmit higher torque. Electronic Differential Lock takes effect when starting off and automatically switched off at the speed of 40 km / h. To one of the advantages of this method of improving traction it relates what mode pulling away it has no adverse effect on the driving mode control and comfort.

The operating principle of EDS

The electronic control unit receives continuous information from the ABS sensors of rotation speed of the drive wheels and with the difference between the numbers of revolutions greater than about 110 min-1 EDS automatically activated and decreases the transmission torque to the revolving wheel as long as its speed is approximately equal to the speed non-skid wheels. Thanks to this control of the wheel with better traction transmitted to the increased torque. The system EDS, as already mentioned, is automatically disabled when the vehicle speed above 40 km / h, as well as cornering and overheating brakes. EDS system is protected from disruptions brake control. The EDS system uses a number of elements of the ABS. If the vehicle is equipped with EDS, ABS hydraulic unit is equipped with an additional valve block EDS, and the electronic ABS control unit 4 (Fig. 12.22) has "sewn" program memory EDS.

Hydraulic unit

Hydraulic assembly and its components are shown in Fig. 12.23 and 12.24.

Removing the hydraulic unit in the following order:

before starting work, disconnect the "minus" wire from the battery terminals;

- To gain access to the control unit ABS, cnimite intake pipe between the air filter and the throttle body;

- Depress the brake pedal about twenty times (in this case applied to the brake pedal force shall be increased) to relieve the pressure in the accumulator pressure;

- Disconnect the electrical connectors and the ground bus on the block ABS;

- Remove the lid of the tank and pump out the brake fluid from the reservoir;

- Unscrewing the connecting nut, remove the brake pipes from the unit. Turn off the ends of the tubes corresponding stoppers;

- In the car with the driver's side, remove the lower instrument panel trim;

- Remove the retaining ring and remove the pin from the brake pedal pusher;

- Unscrew the nuts of the hydraulic block and remove the block.

Install in reverse order of removal.

Before installing the air pipe to remove air from brake system.

The electronic control unit

The electronic control unit is located under the left rear seat cushion.

Removing the unit in the following order:

- Before starting work, disconnect the "minus" wire from the battery terminals;

- Remove the rear seat cushion;

- Loosen the clamp and remove the electrical connector from the pin block;

- Removing the two mounting screws (Fig. 12.25), remove the electronic control unit.

Installation spend to sequences, return to removal.

Make sure that the clip clearly stated pin electric socket on the unit.

Relays and fuses

Anti-lock braking system has two relays: one general relay and the relay of the hydraulic pump. Both relays are located above the main fuse box and relays under the dashboard, driver's side.

Wheel speed sensor

Toothed rotor 2 (Fig. 12.26) sensor rigidly mounted in the wheel hub, rotates together with the wheel. The teeth of the rotor, passing through the magnetic field and the sensor 1 induce an electrical signal in proportional to the wheel speed, which is transmitted to the electronic control unit.

Removal in the following order:

- Before starting work, disconnect the "minus" wire from the battery terminals;

- Hang out the front or rear of the car and fix on support column;

- Remove a corresponding wheel;

- Unscrewing the bolt, remove the sensor (Fig. 12.27) from the knuckle or pins.

Sensor Installation spend to sequences, return to removal.

Before installing the sensor, apply a paste for brake cylinder.

Gear sensor rotor

Front toothed rotor is located on the inner surfaces of the front wheel hub.

To remove the front of the rotor, remove the wheel hub and separate the rotor from the hub.

The rear rotor is located inside the rear hub of the brake disc.

Removing the rear rotor in the following order:

- Before starting work, disconnect the "minus" wire from the battery terminals;

- To remove the rotor, remove the brake disc;

- Pass the rod through the hole under the wheel bolts and remove the rotor hub.

Rotor made in sequence, return to removal.

When installing the gear rotor necessary, use a tubular mandrel of appropriate diameter.

Pressure sensor

On early models of cars pressure sensor mounted in the housing of the master cylinder, and on vehicles manufactured from January 1989 sensor is mounted on the body of the hydraulic pump.