3308520 - 3350A anti - spin regulation devices
In addition to the normal functions carried out by the ABS 5.3 ( See subassembly 3340 A(B.S. ANTI-LOCK BRAKING SYSTEM .) ), the versions equipped with A.S.R. (Antislip regulation) also have an antislip function. This function intervenes when the A.B.S. control unit detects, via the signals received from the active sensors, that the speed of one or both drive wheels is different from that of the driven wheels (slipping).The A.B.S. control unit notifies the presence of slipping and the torque reduction request to the injection control unit via the CAN line.CONTROL SYSTEM
According to the vehicle driving conditions, two different control systems are activated without the driver operating the brake pedal in any way:
- in the case of excessive power with both drive wheels slipping the following takes place:
- an instant reduction in the ignition advances
- a reduction in the butterfly opening angle
- a modulating action of the braking system at the drive wheels.
in the case of only one drive wheel slipping, the following takes place:
- an instant reduction in the ignition advances
- a reduction in the butterfly opening angle
- a braking action at the wheel which is slipping, producing a resistant torque. As a result, the differential transmits the same torque to the wheel with better grip.
 | With the brake pedal depressed, the A.S.R. antislip function acts exclusively on the engine (reduction in torque: ignition advances, butterfly opening angle) to guarantee the maximum efficiency of the A.B.S. braking system. |
 | Whilst driving on a snow-covered surface, with snow chains fitted, it may be useful to switch the A.S.R. function off: under these circumstances the slipping of the drive wheels during take off actually allows improved traction. |
Button/warning light
A button allows the A.S.R. antislip function to be excluded; this is signalled by the LED in the button lighting up. | Each time the vehicle is started up the A.S.R. antislip function is activated. |
OPERATION
The electro-hydraulic unit on versions equipped with A.S.R. have four extra solenoid valves (8) and (9) for the management of the operation of the brakes if the drive wheels are slipping.Intervention during braking
With the brake pedal depressed, the electronic control unit:
- does not supply the solenoid valve (N.C.) (8)
- does not supply the solenoid valve (N.A.) (9).
In this way, the system operates during the following stages:
- pressure increase
- pressure maintenance
- pressure reduction
A.s.r. intervention
If one/both of the drive wheels is/are slipping, then the electronic control unit:
- supplies the hydraulic pump (1)
- supplies the (N.C.) solenoid valve (2)
- supplies the (N.A.) solenoid valve (3).
In addition, the A.B.S./A.S.R. control unit notifies the injection/ignition control unit (CAN line) of the presence of slipping. The latter, decreases the torque supplied by the engine with:
- a reduction in the ignition advances.
- a reduction in the butterfly valve opening.
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.
Hydraulic control unit
The electro-hydraulic control unit consists of:
- twelve 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 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
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