3308518 - 3340A abs check/adjustment devices
ELECTRO-HYDRAULIC UNIT
It consists of an electronic control unit (1) and an electro-hydraulic control unit (2).Electronic control
The electronic control unit is responsible for:
- acquiring the data coming from the 'active' 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 failures at the braking system components
- memorizing the fault codes and activating the A.B.S. and EBD warning lights.
- transmitting and receiving data via the diagnostic connector
- conversing with the injection and CAE control units via the CAN line (only for versions with automatic transmission).
Hydraulic control unit
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
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.
The letters indicating to which caliper and to which brake pump outlet they should be connected are 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 T connector (pipe marked with a black or pink coloured band when the pipe polyamide resin is black)
- MC2 = from the secondary circuit pump/front.
Pin out
-
1, Right rear wheel rpm sensor supply
2, Right rear wheel rpm sensor signal
3, Not connected
4, Right front wheel rpm sensor supply
5, Right front wheel rpm sensor signal
6, Left front wheel rpm sensor supply
7, Left front wheel rpm sensor signal
8, Left rear wheel rpm sensor supply
9, Left rear wheel rpm sensor signal
10, Not connected
11, Diagnostic line K
12, Diagnostic line L
13, Not connected
14, Brake pedal switch positive
15, Control unit positive
16, Earth
17, Positive from battery (+ 30)
18, Positive from battery (+ 30)
19, Electronic earth
20, A.B.S. warning light
21, EBD warning light
22, Not connected
23, Not connected
24, Not connected
25, Not connected
26, Not connected
27, Not connected
28, Not connected
29, CAN line (only for versions with automatic transmission)
30, CAN line (only for versions with automatic transmission)
31, Not connected
ACTIVE SENSORS
They consist of two basic elements:
- a magnetic multi-polar codifier (1) integrated in the 'instrument' wheel hub bearing
- a 'magnetic-resistive' receiver (2) opposite the codifier.
The adoption of active sensors offers the following advantages:
- it reduces sensitivity to electro-magnetic interference
- it saves weight and size
- it simplifies the transmission couplings through the elimination of the phonic wheels.