Repair operations on the unit

either depending on braking pressure (fixed cut) or according to the elongation of the rear suspension.

As a result of this new strategy the control unit controls the tendency of the rear wheels to skid through the ABS sensors, reducing the braking pressure only when this is needed.

The result is better adaptation of the braking force to the conditions of the road surface and maximised efficiency of braking at the rear.

Any fault on the EBD system is shown by the turning on of the "low brake fluid level/handbrake on" warning light on the instrument cluster.

In these conditions the pressure reduction function at the rear wheels is not active. Use the vehicle with extreme caution (see Group 55 - Electric System Diagnosis).

REPAIR OPERATIONS ON THE UNIT

Instructions for correct repairing

• To replace the electronic control unit it is necessary to disassemble the whole hydraulic unit, owing to reasons of space and to avoid damaging the internal connector.
• The electrohydraulic control unit cannot be overhauled and it is fault-proof until it is tampered with. It must be replaced if found to be faulty.
• After each replacement of a hydraulic unit, rpm sensor, electronic control unit or wiring (especially if after an accident) the entire A.B.S. system must be checked with the Tester.
• After all operations on the hydraulic system of the A.B.S. or brake system, it is necessary to fill with DOT 4 brake fluid, relieve the air, and check the tightness of all the connection points.
• The electrohydraulic control unit is supplied filled with DOT 4 brake fluid and with the solenoid valves not supplied. The operation for filling with fluid and relieving the air is the same as for a conventional system, but requires more time.
• During removal of the electrohydraulic unit avoid overturning it to prevent spilling the oil contained in the hydraulic part.
• When refitting pay attention to the unions: to prevent mistakes in connecting the various parts of the braking circuit during repair operations, the connections of the hydraulic modulator unit are of different sizes (M10x1 and M12x1), the unions are also identified by the codes stamped on them.

ABS HYDRAULIC UNIT/ELECTRONIC CONTROL UNIT

Removing/Refitting

• Disconnect the battery
• Remove the corrugated air intake pipe (see group 10).
• Drain the brake-clutch fluid.
• Remove the components that prevent free access to the hydraulic unit.

1. Pull control unit comb locking device forward, then remove it from its housing.
2. Disconnect the pipe fittings from the hydraulic aggregate.
3. Slacken the two fastening nuts and remove the hydraulic aggregate.

13 ÷ 15 Nm
1.4 ÷ 1.5 kgm

When refitting relieve the air from the braking system (see specific paragraph).

NOTE: For further details about system operation and diagnosis, see "GROUP 55 - ELECTRIC SYSTEM DIAGNOSIS". Diagnosis for seeking any faults must be carried out using the ALFA ROMEO TESTER.