DescriptionThe electronic anti-lock brake system (ABS) governs braking pressuresent to the wheels and prevents loss of grip under all tyre androad surface conditions.On the most extensive version the ABS controlunit also includes the ESP (Electronic Stability Program) and ASR(Anti Slip Regulation) functions as well as the HBA (Hydraulic BrakeAssist) and HH functions (Hill Holder)The ESP system acts on the engine and brakesto generate a stabilising torque when the ABS sensors detect conditionsthat could lead to the vehicle slipping.The ESP system includes the followingspecific components over and above those of the ABS:a sensor which detects the steering wheel position (steeringsensor in the electric power assisted steering control unit);a sensor which detects the vehicle's rotation around thevertical axis and side acceleration (centrifugal force) (yaw sensor);a sensor which measures the pressure in the ABS hydraulicunit (incorporated in the ABS control unit)The ESP system is always connected to theASR system.The ASR system increases vehicle stabilityand active safety by controlling drive wheel slip. If slip is causedby excessive power transmission, it cuts in to reduce engine power throughcommunication with the engine management control unit. if slip isdetected at a single wheel, the system cuts in to brake the slippingwheel by acting on the modulation solenoid.The ASR comes on automatically wheneverthe engine is started: the system can be deactivated by operatingthe 'ASR OFF' button in the control panel in the centre of the dashboard.When the system is off, an LED on the buttoncomes on at the same time as a warning light on the control panel.TheESP function, on the other hand, comes on automatically when thevehicle is started up and cannot be switched off.The Hill Holder system is designed to assistthe driver during hill starts. The HH automatically delivers enoughbrake torque to hold the car so that the clutch is not fully released andthe engine torque is high enough to start the car comfortably.The HH activates automatically whenthe brake pedal is pressed under the following circumstances:vehicle speed equal to zero, gradient greater than 2%and clutch pedal pressed.When the brake pedal is released, the HillHolder maintains the brake system under pressure for 2 seconds withoutaltering the other conditions to give the driver time to move his orher foot from the brake pedal to the accelerator pedal without thevehicle moving backwards and without the use of the parking brake.Once the accelerator has been pressed, theHill Holder keeps the car still for an additional 10 seconds oruntil engine torque is high enough to move the car.The H.B.A. system aids the driver duringemergency stops when the brake pedal is applied quickly and maintenanceload is low; the system intervenes when the pressure gradient exceedsa certain threshold (fast application of brake pedal - emergencystop) multiplying the braking pressure at the wheels applied bythe driver to maximize deceleration.ASR/ESP warning light: the warning lightflashes when the system cuts in to notifiy the driver that the ASRsystem has cut in due to road surface grip conditions.When th econtrol unit detects an error inthe ASR function or the ESP function, it lights up the warning lightconstantly.HH warning light: the warning light comeson when the system cuts in to notifiy the driver that the HH systemhas cut in due to road surface grip conditions.The warning light comes in in fixed modewhen the control unit detects an error in the HH function. As far as the ABS function only is concerned, 2428118SeeE7020ABS . For more details 2427426Characteristic of working principle3350DRIVE CONTROL' .
Functional description ABS electronic control unit M50 is supplied (at pins 12 and25) directly by the battery by the line protected by maxifuse F5of the engine compartment junction unit B1. The ignition-operated supply (INT/A) reachespin 23 from the line protected by the fuse F42 of under faciacontrol unit B2.The control unit is earthed via pins 11and 24. The four sensors K70, K71, K75, K76 sendwheel speed signals tp pins 20-19, 8-7, 22-21, 10-9 of M50, respectively. Brake pedal switch I30 sends an enablementsignal to pin 17 of control unit M50: the ABS cannot intervene unlessthe brake pedal is pressed. The switch I30 is suppliedwhen the ignition is switched on (INT) from fuse F37 of junctionunit B2 . Pin 16 ofi M50 emits a discrete speedsignal that is sent tol Body Computer M1; the same signal isalso copied via the CAN network. The steering sensor is contained in theelectric steering control unit M86 which is connected to theABS control unit M50 via the CAN. The yaw (and lateral acceleration) sensor K74receives an ignition-operated supply at pin 1 from the line protectedby fuse F42 of the junction unit under the dashboard B2; pin6 is earthed, whilst pins 5 and 3 are connected to the ABS controlunit M50 via the CAN. The 'ASR OFF' control button on panel H90sends a deactivation signal to pin 3 of M50, while pin 4 relaysa signal that turns on an LED on panel H90 when the system is off; ; Theswitch H90 is supplied when the ignition is switched on (INT)from fuse F49 of junction unit B2. Pins 1 and 2 of ABS control unit M50connect to engine control unit M10, Body Computer M1 and and instrumentpanel E50 to control the ABS, insufficient brake fluid and handbrakeapplied warning lights and the ASR/ESP and HH warning lights.The special 'fault' warning light comeson if there is a problem with one of the above mentioned warninglights. Self-diagnostic data can be read by connectingto connector C of Body Computer M1- pin 1: it receives signalsfrom pin 6 of the control unit M50 via the special diagnostic line.2428143SeeE8010DIAGNOSTIC MULTIPLE CONNECTOR
0Removing201Refitting21Ensure that the ignition key is in theOFF position, then loosen the bolt and disconnect the battery negative(-) terminal.Undo the bolt and disconnect the batteryterminal (+).Undo the battery belt nut.Remove the battery.
5530B22
0Removing201Refitting212429398-5530B10battery - r+r2429401-5530B52Battery DRIP TRAY/SUPPORT - R.R.Open the bonnet lid.1. Disconnect the electrical connection (1a) from the negative batteryterminal (1b).2. Disconnect the electrical connection from the bodyshell.3. Disconnect the electrical connection from the gearbox casing.4. Keep the battery earth lead.2052930
5530B36
0Removing201Refitting21Place the vehicle on a lift.Raise the car.1. Undo the nut (1a) and disconnect the electrical connections (1b,1c) from the starter motor.2052931
5530B52
0Removing201Refitting21 Proceed with removal 2429398-5530B10battery - r+r . 1. Remove drip tray.2. Undo the fixing bolts (2a) and remove the battery cradle (2b)after releasing the electrical wiring from the bands on the cradle.2045035
0Removing201Refitting212429579-7040A30Left instrument panellower TRIM - R.R.1. Disconnect the electrical connections (1a, 1b, 1c, 1d, 1e, 1f).2. Undo the left-threaded bolt securing the facia trim mount beam.3. Undo the bolts securing the body computer/junction unit.4. Move facia trim (4a) slightly and move body computer/junctionunit (4b) downwards.5. Disconnect the electrical connections (5a, 5b, 5c).6. Recover the body computer/junction unit.2045005
0Removing201Refitting211. Disconnect electronic control unit electrical connections (1a),(1b), (1c).2. Undo the bolts.3. Recover the control unit2045007
0Removing201Refitting211. Disconnect electronic control unit electrical connections (1a),(1b), (1c).2. Undo the bolts.3. Recover the control unit2045008
0Removing201Refitting21Ensure that the ignition key is in OFFposition, then disconnect the battery negative terminal (-).1. Disconnect the brake light switch electrical connection.2. Turn and remove the brake light switch.2045071
5550D16
0Removing201Refitting21Open the tailgate.1. Prise up the rubber pads.2. Press the tail-light retainers in the arrowed direction and releasefrom the seat.2045072
0Removing201Refitting21Ensure that the ignition key is in OFFposition, then disconnect the battery negative terminal (-).1. Disconnect the electrical connection from the reversing lightsswitch.2. Undo and remove the reversing lights switch.2045076
0Removing201Refitting21 Proceed with removal 2429398-5530B10battery - r+r . Proceed with removal 2429401-5530B52Battery DRIP TRAY/SUPPORT- R.R. . 1. Remove the protective cap on the brake caliper bleed valve.2. Connect the collection system (pipe and reservoir) to the bleedvalve on the brake caliper.3. Loosen the bleed valve on the brake caliperWait for the brake-clutch reservoir todrain.2044760
0Removing201Refitting21.767The following procedure describesremoval/refitting of the left rear wheel rpm sensor; proceed asfor the right rear wheel rpm sensor.Position the vehicle on the ramp.Ensure that the ignition key is in OFFposition, then disconnect the battery negative terminal (-).1. Undo the bolt (1a) and remove the rear wheel rpm sensor (1b).2. Release the rear wheel rpm sensor electrical wiring from theattachments on the rear suspension.2044773
0Removing201Refitting21 Proceed with removal 2429603-7040L28tunnel switch panel -r r . 1. Undo the bolt (1a), raise sensor (1b) and disconnect the electricalconnection (1c).2044800