Abs check/adjustment devices

Description 3340A

1.6 TS, 2.0 TS

COMPONENT DESCRIPTION

Electrohydraulic unit

Composition

Structure

This consists of an electronic cotnrol unit (1) and an electro-hydraulic control unit (2).

Electronic control

Specifications

Function

The electronic control unit performs the following functions:

• downloading data from the wheel rpm sensors
• storing control parameters defined during the preparation of the vehicle
• storing the control software
• processes downloaded data
• controls the braking process
• detecting ABS component faults
• memorizing fault codes and activating the A.B.S. and EBD warning lights
• sending and receiving data via the C-CAN line
• transmitting and receiving data via the diagnostic connector

PIN OUT

1 - Power earth

2 - + 30 power supply

3 - N.C.

4 - N.C.

5 - Signal earth

6 - +30 power source

7 - N.C.

8 - N.C.

9 - N.C.

10 - N.C.

11 - Diagnostic line K

12 - Front left sensor signal

13 - Rear left sensor positive

14 - Rear left sensor signal

15 - Front right sensor positive

16 - Rear left sensor signal

17 - N.C.

18 - N.C.

19 - N.C.

20 - N.C.

21 - N.C.

22 - N.C.

23 - +15 power source

24 - CAN line

25 - N.C

26 - N.C.

27 - N.C.

28 - Front left sensor positive

29 - N.C.

30 - Rear right sensor positive

31 - Rear right sensor signal

32 - N.O. brake button

33 - N.C.

34 - N.C.

35 - N.C.

36 - N.C.

37 - Vehicle speed VSO (recovery)

38 - N.C.

39 - N.C.

40 - CAN L Line

41 - N.C.42 - N.C.

CIRCUIT DIAGRAM

A - Solenoid relay

B - Pump motor

C - Pump motor

D - Valve unit

E - Electronic control unit

FL - Front left sensor

FR - Front right sensor

RL - Rear left sensor

RR - Rear right sensor

1A-1B - Left front wheel solenoid

3A-3B - Right front wheel solenoid

4A-4B - Left rear wheel solenoid

2A-2B - Right rear wheel solenoid

Hydraulic control unit

Specifications

Function

Responsible for modulating the pressure of the fluid at the brake calipers via two solenoid valves with the following stages:

• brake fluid pressure increase
• brake fluid pressure maintenance
• brake fluid pressure discharge

Composition

Structure

The electro-hydraulic control unit consists of:

• eight two-way solenoid valves
• a dual circuit electric recovery pump
• two low pressure accumulators
• two high pressure accumulators

The letters indicating to which caliper and to which brake pump outlet they should be connected at stamped on the control unit at each outlet:

• RR = to the right rear brake (pipe marked with a light blue coloured band)
• LR = to the left rear brake (pipe marked with a green coloured band)
• RF = to the right front caliper (pipe marked with a yellow coloured band)
• LF = to the left front caliper (pipe marked with a white coloured band)
• MC1 = from the main circuit/flange side pump (pipe marked with a black or pink coloured band when the pipe polyammide resin is black)
• MC2 = from the secondary circuit/front pump (pipe marked with a brown coloured band).

1 - Brake servo pump

2 - Hydraulic control unit

3 Rear left wheel

4 - Front right wheel

5 - Front left wheel

6 - Rear right wheel

Active sensors

Specifications

Features of the system

The adoption of active sensors offers the following advantages:

• less sensitivity to the distance between the sensor and the magnetic ring (gap)
• it reduces sensitivity to electro-magnetic interference
• the active sensor is able to measure wheel rpm speeds down to zero (instead of 2.5 km/h with the passive sensor)
• it saves weight and size
• it simplifies the transmission couplings through the elimination of the phonic wheels.

Composition

Structure

The active sensors consist of two basic parts:

• a magnetic multi-polar codifier (1) integrated in the instrumented wheel hub bearing
• a magnetoresistive receiver (2) facing the codifier.

FRONT SENSOR

REAR SENSOR

Operation

Introduction

The operation of the sensor is based on the variation in the internal electrical resistance depending on the intensity and the direction of the lines of force of an external magnetic field (multipolar magnetic codifier) producing a variable square wave signal whose frequency depends on the rotation speed of the wheel, but whose range is constant.

The active sensor is thus a proximity sensor with its own electronic system. It is connected to the ABS control unit by means of an electrical supply cable and sends vehicle speed information to the control unit.

The phonic ring is a multipolar ring, an elastomer with a certain quantity of magnetic particles which are aligned by means of a special magnetization technique to produce different magnets with alternating north and south polarity around the circumference of the ring.

1 - Magnetised sealing ring

2 - Bearing

3 - Sensor head

4 - Active sensor

5 - Sealed connector