DescriptionThe electronic anti-lock brake system (BOSCH 5.3 ABS) governs braking pressure sent to the wheels and prevents loss of grip under all tyre and road surface conditions.The system is designed to complement the normal mechanical braking system and not to replace it. In this way it ensures effective safety in the case of anomalies: the ABS uses the same fluid as the conventional mechanical braking system.Four sensors fitted to the four wheels inform the electronic control unit of wheel speed at every moment. In this way, they detect wheel lock, wheel slip and loss of grip. Under these conditions, the control unit sends specific instructions to solenoids that modulate hydraulic circuit pressure to eliminate lock and restore the car to within grip limits. This ensures the shortest possible stopping distance, without losing control of the steering.Two adjustment solenoids (one for pressure charging, the other for pressure discharging) are fitted for each wheel.The sensors are active, i.e. they consist of a Hall-effect receiver that faces a magnetic coding device built into the hub bearing. Under these conditions, the signal is less influenced by electromagnetic interference and temperature.The control unit also controls brakeforce distribution over the rear axle and thus replaces the mechanical lload proportioning valve used previously (EBD function: Electronic Brake Distribution).The control unit is equipped with a self-diagnostic function: when an error occurs in the ABS system, a warning light is turned on and the system is simultaneously deactivated. Under these conditions, the car brakes using only the conventional system.When the control unit detects an error in the EBD function, it simultaneously turns on the 'insufficient brake fluid level' and 'handbrake on' warning light as well as the ABS warning light.Under these conditions, the rear brake distribution control is also deactivated and the car must be driven with great care. For more details 3308517see DESCRIPTION AND OPERATION:3340A(B.S. ANTI-LOCK BRAKING SYSTEM .)Supply lines to the control unit and the various system components (sensors and actuators) are protected by a maxifuse and a jumper fuse located in the engine bay.
Functional description The ABS electronic control unit M50 is supplied directly by the battery at pin 6 from the line protected by ABS maxifuse B7, and at pin 2 from the line protected by maxifuse B34 . The ignition-operated supply (INT/A) reaches pin 23 from the line protected by the fuse B31 . The control unit is earthed via pins 5 and 1. The four sensors K70, K71, K75, K76 send the wheel speed sensors to pins 12-28, 15-16, 13-14 and 30-31 of M50 respectively. The brake pedal switch l30 is supplied when the ignition is switched on by two specific lines, protected by fuses F5 and F1 of the junction unit B1 . The switch l30 indicates to the control unit M50 its operating state: if the pedal is pressed, the control unit M50 receives the signal at pin 37, whereas with the pedal pressed, the signal reaches pin 32. Pin 33 of M50 produces a speedometer signal (average speed of all four wheels) which is directed to instrument panel E50 - pin 2 of connector B ( 3309717SeeE4010INSTRUMENT PANEL ). The ABS includes a self-diagnostic system: when the control unit detects problems with the ABS, it sends a signal from pin 20 of instrument E50 - pin 18 of connector C - which turns on the ABS fault warning light. This warning light is managed by the processor in the instrument panel E50 , which receives and processes the signal coming from the control unit M50 . If the problems line in the EBD function, the control unit also sends a signal from pin 17 and 38 of the instrument panl E50 - pins 10 and 19 of connector C - to the low brake fluid and handbrake warning light ( SeeE4010 INSTRUMENT PANEL ). Both the signals sent to the instrument are earth signals, and they make the warning lights come on, as the instrument panel E50 is ignition activated (INT/A) from the line protected by fuse F1 of the junction unit B1 . The self-test data can be read by connecting to pin 1 of connector R10 : it receives signals from pin 11 of the control unit M50 via the specific diagnostic line.
<anchor>0</anchor><span>Removing</span><icon><imageid>20</imageid></icon>1Refitting213314824-5505A18multi-function controlunit - r r . 1. Undo the bolt (1a) and push back the junction unit as far asnecessary to disconnect the electrical connections (1b).767For precise identification ofthe electrical connections, see Wiring Diagrams Section.2. Remove the junction unit.2010592
<anchor>0</anchor><span>Removing</span><icon><imageid>20</imageid></icon>1Refitting21 Make sure that the ignitionis off (STOP position), then disconnect the negative battery terminal(refer to op. 33148615530B10battery - r+r ). 1. Unscrew bolt (1a) and open fuse access cover (1b).2. Undo the bolt (2a) and remove the integrated multiservices unit(2b) after having disconnected the electrical connections (2c),(2d), (2e), (2f) and (2g).2010595
5505A29
<anchor>0</anchor><span>Removing</span><icon><imageid>20</imageid></icon>1Refitting21Open the bonnet lid.1. Release the retainers (1a) and remove the cover (1b) for theadditional junction unit.2071293
<anchor>0</anchor><span>Removing</span><icon><imageid>20</imageid></icon>1Refitting213314864-5530B54battery cover - r+r . Make sure that the ignition key is in theOFF position.1. Disconnect the battery negative and positive terminals.2. Undo the bolt (2a) fixing the battery retaining bracket (2b).3. Remove the battery.2010647
5530B40
<anchor>0</anchor><span>Removing</span><icon><imageid>20</imageid></icon>1Refitting213314864-5530B54battery cover - r+r1. Press and release the retainers (1a), then remove the cover (1b)for the supply box on the battery. 2071303
<anchor>0</anchor><span>Removing</span><icon><imageid>20</imageid></icon>1Refitting211. Working in the luggage compartment, undo the knob for the batterycover.2. Remove the battery cover.2010650
<anchor>0</anchor><span>Removing</span><icon><imageid>20</imageid></icon>1Refitting213314917-5560B11analogue control panel- r+r or replace . 1. At the bench, remove the bulbs from the panel using suitablepliers.2010702
5560B11
<anchor>0</anchor><span>Removing</span><icon><imageid>20</imageid></icon>1Refitting21 Make sure that the ignitionis off (STOP position), then disconnect the negative battery terminal(refer to op. 33148615530B10battery - r+r ). Lower the steering wheel and move it back.1. Undo the bolts (1a) and remove the upper half casing for thesteering column (1b).2010703
5560B12
<anchor>0</anchor><span>Removing</span><icon><imageid>20</imageid></icon>1Refitting21 Make sure that the ignitionis off (STOP position), then disconnect the negative battery terminal(refer to op. 33148615530B10battery - r+r ). Open the fuse carrier compartment flap.1. Using the tool (1a) and pushing the fuse carrier compartment,remove the surround (1b) complete with switches.2. Disconnect the elelectrical connections (2a), (2b) and (2c) andremove the surround complete with switches.2010706
<anchor>0</anchor><span>Removing</span><icon><imageid>20</imageid></icon>1Refitting21 Make sure that the ignitionis off (STOP position), then disconnect the negative battery terminal(refer to op. 33148615530B10battery - r+r ). 1. Remove the caps (1a) and undo the bolts (1b) fixing the thirdbrake light to the rear parcel shelf.2. Disconnect the electrical connection (2a) and remove the thirdbrake light (2b).2010698
5550D17
<anchor>0</anchor><span>Removing</span><icon><imageid>20</imageid></icon>1Refitting21 Make sure that the ignitionis off (STOP position), then disconnect the negative battery terminal(refer to op. 33148615530B10battery - r+r ). 3314911-5550D16third stop light - r+r . 1. Undo the bolts (1a) and remove the bulb holder (1b).2010699
5550D18
<anchor>0</anchor><span>Removing</span><icon><imageid>20</imageid></icon>1Refitting21 Make sure that the ignitionis off (STOP position), then disconnect the negative battery terminal(refer to op. 33148615530B10battery - r+r ). 3315223-7040L20tunnel trim - r r1. Undo the nut (1a) and disconnect the earth lead (1b).2. Disconnect the electrical connection from the handbrake warninglight switch.3. Undo the nut (3a) and remove the handbrake warning light switch(3b).2010701
<anchor>0</anchor><span>Removing</span><icon><imageid>20</imageid></icon>1Refitting21Position the vehicle on theramp. Make sure that the ignition is off (STOPposition), then disconnect the negative battery terminal (referto op. 33148615530B10battery - r+r ). 3315196-7040D12engine front side cover (one) lh or rh - r r (left). 3315197-7040D14engine bay rear side cover (one) lh or rh - r r (left). Remove the cap with built-in brake fluidlevel switch and drain the brake/clutch fluid from the reservoir usinga suitable syringe.1. Disconnect the comb from the A.B.S. hydraulic and electroniccontrol unit.2. Release the A.B.S. pipes from their clip.3. Disconnect the pipes from the A.B.S. hydraulic and electroniccontrol unit and move them aside.2009904
<anchor>0</anchor><span>Removing</span><icon><imageid>20</imageid></icon>1Refitting21Position the vehicle on thelift. Make sure that the ignition is off (STOPposition), then disconnect the negative battery terminal (referto op. 33148615530B10battery - r+r ). 3315196-7040D12engine front side cover (one) lh or rh - r r (right) 3315197-7040D14engine bay rear side cover (one) lh or rh - r r (right) 1. Release the front right wheel speed sensor wiring from its clamp.2. Disconnect the electrical connection for the front right wheelspeed sensor.3. Release the rubber cable pass for the front right wheel speedsensor wiring from the bodywork.2009919
3340A35
<anchor>0</anchor><span>Removing</span><icon><imageid>20</imageid></icon>1Refitting21Position the vehicle on thelift.3314864-5530B54battery cover - r+r . 3314861-5530B10battery - r+r . 3314863-5530B52Battery DRIP TRAY/SUPPORT - R.R. . 1. Disconnect the electrical connection (1a) for the rear rightwheel speed sensor and release the wiring from the clip (1b).2. Release the rubber cable pass from the rear left wheel speedsensor from the bodywork.2009921
