3308521 - 3350C tcf 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 T.C.S. (Traction Control System) also have an antislip function.The T.C.S. function is only activated when the speed of the vehicle is below 40 kph and if the slipping is caused by:
- a take-off stage
- fierce acceleration
- poor adhesion (snow, earth etc. on the road surface)
Button/warning light
A warning light in the instrument panel signas:
- the disengagement of the T.C.S. - warning light on
- the intervention of the T.C.S. - warning light flashing.
Each time the vehicle is started up the T.C.S. function is activated. |
OPERATION
The electro-hydraulic unit on versions equipped with T.C.S. have four extra solenoid valves (8) and (9) which manage the braking in the case of 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
1, Master cylinder
2, High pressure accumulator
3, Pump
4, Low pressure accumulator
5, Pressurizing solenoid valve
6, Discharge solenoid valve
7, Brake calipers
8, Inlet solenoid valve
9, Operating solenoid valve
T.c.s. intervention
With the drive wheels slipping, the electronic control unit:
- supplies the hydraulic pump (1)
- supplies the (N.C.) solenoid valve (2)
- supplies the (N.A.) solenoid valve (3).
1, Pump
2, Inlet solenoid valve
3, Operating solenoid valve
4, Brake calipers
5, Pressurizing solenoid valve
6, Discharge solenoid valve
ELECTRO-HYDRAULIC UNIT
It consists of an electronic control unit (1) and an electro-hydraulic control unit (2).
1, Solenoid valves
2, Electronic control unit
3, Electrical connection
4, Relay
5, Electric motor
6, Electro-hydraulic unit casing
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.
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 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 (+ 15)
16, Power 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, Vehicle speed output (VSO)
23, Not connected
24, T.C.S. LED
25, Not connected
26, Not connected
27, Not connected
28, A.B.S./T.C.S. failure warning light
29, Not connected
30, Not connected
31, T.C.S. button