Table of Contents E70 Longitudinal Dynamics Systems Subject Page Introduction .5 Longitudinal Dynamics Systems.5 ABS in DSC .5 Dynamic Stability Control (DSC) .6 Electromechanical Parking Brake (EMF) .6 Dynamic Cruise Control (DCC) .6 New Features ofthe DSC E7x.12 Classic Brake Control Functions.13 Additional Brake Control Functions .14 Basic Functions ofthe EMF.16 Emergency Release .16 Restoring Operation After Emergency Release .16 Service Functions .17 Example Scenarios .17 Transition from EMF Actuating Unitto DSC .17 Transition from DSC to EMF Actuating Unit.18 Function ofthe Parking Brake Controlled by the DSC Hydraulics_18 Scenario: "Engine running" .18 Scenario: "At rest" .18 Dynamic Braking .18 Exiting Dynamic Emergency Braking .19 Error Messages .20 General Parking Brake Fault Concept .20 Fault Distribution Between DSC and EMF Control Unit.20 Fault Regeneration.21 Monitoring and Fault Detection.22 System Components.23 Hydraulic Unit with Add-on Control .23 DSC Control Unit .23 Wheel Speed Sensor.28 Steering Column Switch Cluster .30 SZL Electronics.31 Steering Angle Sensor.31 Code Disc .31 Initial Print Date: 10/06 Revision Date: 11/06 Subject Page Optical Sensor .32 Line Camera .32 DSC Sensor.33 Electromechanical Parking Brake (EMF).34 EM F Button.34 Emergency Release .35 Using the E70 EM F Emergency Release .36 Electromechanical Actuating Unit .37 EM F Actuating Unit Opened .38 Force Sensor.39 Cruise Control with Brake Intervention (DCC).40 Service Information.42 Adjusting the Brake Shoes .42 Removing the Bowden Cable Assemblies.42 Start-up .43 Initializing the Parking Brake .43 Bedding in the Duo-servo Brake .43 Function on Brake Rolling Dynamometer.44 Subject Page Longitudinal Dynamics Systems Model: E70 Production: From Start of Production ■Biiermis After completion of this module you will be able to: • Understand the integration of ABS, DSC, EM F and DCC in Longitudinal Dynamics System. • Describe the operation of Longitudinal Dynamics System. • Identify the components that operate Longitudinal Dynamics System. 4 E70 Longitudinal Dynamics Systems Introduction Longitudinal Dynamics Systems By applying today's standard consideration aspects, subdividing the functions of driving dynamics systems into the three co-ordinate axes results in the use of three different systems that belong to longitudinal dynamics on the E70. Longitudinal dynamics systems (effective direction mainly on the x-axis or longitudinal axis): • (ABS) Anti-lock braking system • (DSC ) Dynamic stability control • (EMF) Electromechanical parking brake • (DCC) Dynamic cruise control (cruise control with brake intervention) ABS in DSC The ABS prevents the wheels locking while braking and therefore ensures that the vehi¬ cle stays on track and can be steered in critical situations. ABS is constantly activated during vehicle operation and cannot be switched off by the driver. The four wheel speed sensors send data to the DSC control unit that monitors the speed of each wheel. If one or several wheels decelerate at a faster rate than permitted, the DSC control unit activates the hydraulic unit, which in turn reduces the hydraulic pressure in the corresponding brake line. The DSC control unit and the hydraulic unit make up one assembly. When the DSC control unit requests intervention of the antilock braking system, it acti¬ vates the inlet and outlet solenoid valves in the hydraulic unit of the affected brake line and switches on the return pump. The inlet valve closes in orderto disconnect the brake line(s) from the master brake cylinder and the outlet valve opens to allow the brake fluid of the affected brake circuit to escape into the reservoir in orderto reduce the pressure in the circuit. Consequently, the braking effect is reduced and the wheel begins to turn. The DSC control unit then opens and closes the inlet and outlet valves in such a way as to ensure the optimum braking pressure is built up at each wheel without the wheels locking. The return pump conveys brake fluid from the equalizing reservoir of the master brake cylinder, thus maintaining a constant brake fluid pressure downstream of the inlet valves so that the pressure in the brake lines is immediately re-established when the inlet valves are open again. In the case of braking with ABS assistance, the driver normally obtains feedback in the form of pedal vibration and the noise of solenoid valves orthe pump. This is reduced to a minimum by the high-performance hydraulic unit of the DSC E7x in the E70. 5 E70 Longitudinal Dynamics Systems Dynamic Stability Control (DSC) The E70 is equipped with a new generation of the dynamic stability control system. Note: To date, the DSC driving dynamics system on all-wheel drive vehicles was referred to with the abbreviation 11 DXC". Since this lead to confusion with the xDrive, in the future the dynamic stability control sys¬ tem will be known as DSC also on all-wheel drive vehicles. This new generation of the dynamic stability control (DSC E7x, supplied by Bosch) in the B M W X5 is actually the only driving dynamics system that covers all three areas of longi¬ tudinal, transverse and vertical dynamics with its control intervention functions and its modularfunctional structure. With its varied control strategies, the DSC ensures outstanding driving stability within physical limits, active safety and excellent traction in all driving situations. Electromechanical Parking Brake (EMF) The electromechanical parking brake was used forthe first time at BMW on the E65 (7 Series). In principle, the task of the parking brake is to secure the stationary vehicle to prevent it rolling away. The parking brake firmly holds the parked vehicle. In contrast to the parking brake that to date was based on a pure mechanical hand brake and foot brake system, the EMF is designed as an automated, comfort-oriented parking brake system where the driver can apply and release the parking brake by the push of a button. The design layout of the parking brake system is in keeping with typical BMW require¬ ments: • Exclusion of all safety-critical situations • Optimum functionality • Maximum system availability • High degree of comfort and convenience Besides complying with the legal requirement of mechanically holding the parked vehicle and providing an independently operable parking brake in addition to the service brake, one of the main advantages of the EMF is that it enables dynamic braking with DSC con¬ trol. Dynamic C ruise C ontrol (DC C) The dynamic cruise control is a conventional cruise control system (Tempomat) which features additional functions including active brake intervention. Cruise control with brake intervention (DCC) was introduced forthe first time at BMW on the E90 (3 Series). 6 E70 Longitudinal Dynamics Systems DSC Bus Overview JB DSC SIN IHKA SZL DSC DME DDE CAS VGSG GWS Index Explanation Index Explanation KOMBI Instrument cluster DSC Dynamic stability control IHKA Automatic climate control DME Digital motor electronics CAS Car Access System EMF Electromechanical parking brake J B J unction box VGSG Transfer box control unit DSC_SEN DSC sensor GWS Gear selector lever SZL Steering column switch cluster 7 E70 Longitudinal Dynamics Systems DSC Circuit Diagram 8 E70 Longitudinal Dynamics Systems Legend for DSC Circuit Diagram Index Explanation Index Explanation 1 Wheel-speed sensor, front left 11 Brake light switch 2 Brake pad wear indicator, front left 12 Instrument cluster 3 Brake fluid level sensor 13 Center console switch cluster 4 Digital motor electronics 14 Automatic climate control 5 Dynamic stability control 15 Gear selector lever 6 Wheel-speed sensor, front right 16 DSC sensor 7 J unction-box ECU 17 Transfer box control unit 8 Wheel-speed sensor, rear right 18 Steering column switch cluster 9 Brake pad wear indicator, rear right 19 Car Access System 10 Wheel speed sensor, rear left DSC System Overview Index Explanation Index Explanation 1 Hydraulic unit with DSC control unit 5 Center console switch cluster 2 Wheel speed sensor (4x) 6 Steering column switch cluster 3 Master brake cylinder 7 Gear selector lever 4 DSC sensor 8 EMF actuating unit 9 E70 Longitudinal Dynamics Systems EMF Schematic Circuit Diagram -I) - 1 KJ.SGq* □ Kombi K130* K! S&?» 10 E70 Longitudinal Dynamics Systems je □ DSC Legend forEMF Schematic Circuit Diagram Index Explanation Index Explanation 1 Wheel-speed sensor, front left 5 Instrument cluster 2 Dynamic stability control 6 Gear selector lever 3 Digital motor electronics 7 EMF actuating unit 4 J unction-box ECU EMF System Overview Index Explanation Index Explanation 1 Dynamic stability control 4 EMF actuating unit 2 Master brake cylinder 5 E mergency release EMF 3 Gear selector lever 11 E70 Longitudinal Dynamics Systems New Features of the DSC E7x The system supplierforthe DSC E7x is Bosch. With its optimized control functions, the new system design makes a significant contribution to increased driving dynamics. Additional functions for active safety and additional comfort have been implemented in the new system.The new system in the E70 offers the following advantages: • Driving Dynamics - DSC mode: Increased driving dynamics and maximum traction. Thanks to more precise and faster control interventions, the driver can further extend the bound¬ aries of driving dynamics while retaining vehicle safety. - DTC mode: Compared to DSC mode, Dynamic Traction Control (DTC) allows for increased slip at the drive wheels to provide maximum propulsion when driving off in snow for instance. In addition, the stabilizing control interventions cut in later in DTC mode thus allowing a more sport-oriented driving profile. • Active Safety - The additional functions of brake standby, dry braking and fading assistance short¬ en the stopping distances. - Increased DSC efficiency makes for more effective safety-relevant functions. • Comfort - Improved operating comfort (brake interventions are less audible, pedal vibration is drastically reduced) through the use of a 6-piston pump in connection with a new higher-frequency electrical actuation system. - Additional functions such as start-off assistant and parking brake provide increased driver assistance and comfort. 12 E70 Longitudinal Dynamics Systems Classic Brake Control Functions • Antilock Braking System (ABS) ABS prevents individual wheels from locking while braking by targeted modulation of the braking pressures. The steerability of the vehicle through the front wheels is largely retained. When braking on road surfaces with different coefficients of friction, the straight-ahead position is stabilized in co-operation with the active steering (option). • Cornering Brake Control (CBC) (CBC) keeps the vehicle under control when braking lightly in fast corners by asym¬ metric control of the braking pressure, thus improving the cornering stability. • Automatic Stability Control (ASC) (ASC) prevents spinning ofthe drive wheels by way of specific brake application and influencing the drive torque delivered by the combustion engine thus optimizing the forward propulsion ofthe vehicle. • Dynamic Brake Control (DBC) If an emergency braking operation is initiated by the driver, the system assists the driver by automatically applying the maximum braking pressure immediately in order to optimize the braking effect. • Automatic Differential Brake (ADB-X) ADB-X replicates the function ofthe differential locks: if a wheel tends towards spin¬ ning, it is automatically braked so that forward propulsion can still be achieved through the other wheel on the axle. • Dynamic Stability Control (DSC) A vehicle which tends to understeer or oversteer is stabilized by specific brake inter¬ vention on individual wheels.This function operates on the E70 togetherwith the active steering (option). • Hill Descent Control (HDC) HDC automatically applies the brakes at individual wheels when driving downhill at low speed, particularly on poor surfaces such as sand, gravel or snow. The function is activated by means of a button in the center console. • Trailer Stabilization Logic This function automatically detects when a vehicle with a trailer begins to sway and it stabilizes the vehicle-trailer combination by specific brake intervention thus reducing the speed to below the critical shear/swerve level. 13 E70 Longitudinal Dynamics Systems Additional Brake Control Functions • Dynamic Traction Control (DTC) DTC represents a special mode of DSC which, while interacting with (ASC), (ADB-X) and xDrive, realizes maximum propulsion on loose surfaces such as snow, sand or gravel, by extending the slip thresholds. The stabilization interventions in connection with DTC cut in laterthan with DSC thus enabling a more sport-oriented driving pro¬ file. • Brake Standby This function builds up a moderate braking pressure in the system when the driver very quickly takes his/herfoot off the accelerator pedal. The braking effect then cuts infasterto assist the driver in emergency braking. • Dry Braking This function lightly applies the brake pads at specific intervals depending on the operation of the windscreen wiper in orderto dry the brake discs.This distinctly improves the braking effect in braking operations. • Fading Assistance This function assists the driver in applying the braking force when the brake temper¬ ature is very high due to an extreme driving profile which requires a higher braking force in orderto achieve the required braking effect. • Start-off Assistant The start-off assistant holds the vehicle on gradients for about. 1.5 seconds after the driver has taken his/her foot from the brake. In this way, the driver can conve¬ niently operate the accelerator pedal without the vehicle rolling back. • Electromechanical Parking Brake (EMF) The EMF is a parking brake that can be applied and released by means of a bidirec¬ tional button. Depending on the respective vehicle operating situation, the holding force is applied wither hydraulically via the DSC or mechanically via EMF. 14 E70 Longitudinal Dynamics Systems DSC Functions Function Can be DSC ON DTC DSC OFF Symbols: • = System active X = System with elevated control thresholds © = Can be switched on/off 15 E70 Longitudinal Dynamics Systems Basic Functions ofthe EMF The parking brake (EMF) has two different functions, depending on the operating status ofthe vehicle. • Parking brake mode - When the engine is running orthe vehicle is rolling, the parking brake acts on the service brake with the aid ofthe DSC hydraulics. This means the brake units on the front and rear axle are active. - If the engine is not running and the vehicle is stationary, the electromechanical actuator and its cable assembly ensure the parking brake acts on the duo-servo drum brake on the rear axle. In this case, the vehicle is braked as defined in the con¬ trol unit. • Dynamic braking Defined retardation is triggered via the DSC system if the parking brake button is pulled up while driving.The retardation or deceleration is monitored bythe DSC control functions and takes place for as long as the parking brake button is pulled Emergency Release A mechanical emergency release facility is provided in orderto be able to release the parking brake in the event ofthe electromechanical actuating unit failing or insufficient power supply. CAUTION!!! Secure vehicle to prevent it rolling before operating the emergency release! The release procedure is performed manually with the emergency release cable assem¬ bly and the emergency release handle from the vehicle tool kit. The emergency release procedure releases the duo-servo drum brake by way of mechanical intervention in the actuator of the electromechanical control unit. Note: After a powerfailure, it may still not be possible to move the vehicle even after releasing the brake with the emergency release facility. The park¬ ing lock ofthe automatic gearbox may still be engaged (see Product Information Automatic Gearbox E70). 0 nee released, using the emergency release facility, the parking brake cannot be reacti¬ vated manually. The function can be restored only byway of electrical activation. Restoring Operation After Emergency Release Afterturning on the ignition, push down the EM F operating button and pull up again to activate the parking brake. 16 E70 Longitudinal Dynamics Systems Service Functions After replacing the brake shoes of the duo servo drum brake as part of repair or mainte¬ nance procedures, the new brake shoes must be bedded-in to ensure adequate holding effect of the new brake shoes. The software of the EMF control unit features a "bedding- in" service mode that must be activated in this case with the BMW diagnostic system. Indicator/warning lamps in the instrument cluster signal the operating status as well as system fault situations. In the event of faulty signals, the system causing the problem enters corresponding fault codes in the control unit and the system is partially or totally shutdown corresponding to the situation. The driver receives additional information on any restricted functions in the control display. Note: It is only possible to coastorpush the vehicle with the transmission in position N. Neutral usually remains selected fora maximum of 30 min¬ utes. If the vehicle is stationary for longer, the automatic transmission parking lock will automatically be engaged. Example Scenarios Basic function of the parking brake controlled by the actuating unit Scenario: "Ignition ON", the engine is not yet running and the foot brake is pressed. With the vehicle stationary, the parking brake is released or applied by pulling or pressing the EMF button. The indicator lamp in the instrument cluster either goes out or lights up red. Note: The parking brake can be released only with the foot brake pressed when the engine is running orturned off. The dynamic braking function is triggered if the EMF operating button is pulled while the vehicle is rolling. Transition from EMF Actuating Unit to DSC The system switches overfrom mechanical to hydraulic mode when the engine is start¬ ed. If the EMF actuating unit was applied at the time, the DSC hydraulics will assume control of the braking force. The EMF actuating unit is not released until the hydraulics are holding the vehicle secure. The indicator lamp remains lit red throughout this process, and the driver is unaware of the transition (the lamp does not even flash). 17 E70 Longitudinal Dynamics Systems Transition from DSC to EMF Actuating Unit The transition to the EM F actuating unit always takes place on exiting the hydraulic func¬ tion at "ignition OFF". If the parking brake was applied, the hydraulics are not released until the EMF actuating unit is applied.The indicatorlamp remains red throughout this transition. Function ofthe Parking Brake Controlled by the DSC Hydraulics Scenario: "Engine running" The parking brake is applied or released completely by hydraulic means when the EM F operating button is pulled or pressed. Dynamic braking ( hydraulic) is triggered with the vehicle rolling and the button operated atv>3 km/h. The basic functions mainly correspond to the functional scope of a conven¬ tional mechanical parking brake. The system switches between "brake applied" and "brake released" with pressure build¬ up and pressure reduction every time the EMF button is pulled or pressed. The parking brake must be released by pressing the EM F button before starting off. Pulling away against the applied brake pressure results in an increase in pressure and a warning to the driver. Scenario: "At rest" Remove control removed The parking brake enters rest status when the remote control is removed. If the parking brake is applied, the time-delayed red indicatorlamp signals this status to the driver. If the EM F actuating unit is released in rest mode, the EM F actuating unit is applied when the EM F button is pulled with the vehicle stationary. If the vehicle is in motion, pressing the button will initiate dynamic braking. Note: Always take the remote control with you when leaving the vehicle otherwise children could release the parking brake. Dynamic Braking Two braking units for brake operation are required by law (previously: foot brake and hand brake) In the E70, the second operating point besides the foot brake is the EM F button on the gear selector lever. The vehicle is braked by the drum brakes at the rear axle if the EMF button is pressed and held at speeds below v = 3 km/h and with the engine switched off. The vehicle is braked at a rate of 3 m/s2 for 0.8 seconds if the EMF button is pressed when the vehicle is in motion. Braking power is then ramped up to 5 m/s2 forthe next 2 seconds. This braking action is retained for as long as the EMF button is pulled. 18 E70 Longitudinal Dynamics Systems For stability reasons (over-braking - rear axle) the dynamic braking function is also trig¬ gered in the rest state in response to the vehicle rolling (engine turned off, ignition OFF) by means of active pressure build-up by the DSC hydraulics together with the DSC func¬ tion. The brake pressure required is made available as rapidly as possible. The braking action is always monitored by the DSC control function. This ensures vehicle stability while braking. Since all four wheels are braked hydraulically, there is considerably greater deceleration with a minimum of operating effort (EM F button) by comparison with conventional parking brakes.The controlled brakes are therefore able to contribute to improving vehicle safety. Fortraffic safety reasons, operation of dynamic braking is indicated to the road users behind by the brake lights coming on. To avoid accidental operation and misuse, the driver is notified of dynamic braking opera¬ tion by a display message and gong. This function is intended only for use in an emergency and must never be used as a sub¬ stitute for normal operation of the service brake. The more effective braking solution is used if the parking brake deceleration request is overlapped by the brake pedal being depressed. The DSC control unit decides which deceleration request is to be carried out. Exiting Dynamic Emergency Braking The vehicle will remain hydraulically braked even afterthe EMF button has been released if the vehicle is braked to a halt by dynamic braking. There is a transition to the normal DSC hydraulics function.The hydraulic brake is only released when the EMF button is pressed once more. If the EMF button is pressed while the vehicle is still in motion, the system level prevailing before the emergency dynamic braking was activated is resumed. If the parking brake is released and the vehicle is coasting, it is possible to activate emergency dynamic braking in any situation (terminal 30,15, R) by pressing the EM F button. 19 E70 Longitudinal Dynamics Systems Error Messages All fault statuses are detected by the monitoring system and displayed to the driver. The main aim is to avoid safety-critical conditions for vehicle occupants, the vehicle and its surroundings. A fault can be assigned different priorities depending on the driving situation (vehicle sta¬ tionary/in motion, starting/stopping) and the system availability. In addition to the indicator lamp, supplementary instructions may be shown in the control display. To avoid additional damage, faults in the parking brake mechanism, particularly a broken cable in the operating cable assembly and excess load are detected by the force sensor and indicated accordingly. See shutdown strategy table. Error messages can no longer be output actively in the event of the EMF control unit fail¬ ing. In this case, the instrument cluster assumes the control of the correct error message on recognizing the absence of the regular EM F telegram via the PT-CAN (alive signal). Shut-down Strategy Fault Availability Back-up System Parking brake (mechanical) v = 0 Dynamic braking (hydraulic) v >0 CAN signal OK OK DSC hydraulics OK NA Service brake + hand brake Actuating mechanism NA OK Park position auto¬ matic gearbox EMF control unit NA NA Park position auto¬ matic gearbox and service brake and auxiliary brake if necessary General Parking Brake Fault Concept Fault Distribution Between DSC and EMF Control Unit Only DSC faults that actually affect operation of the parking brake result in shut-down of the hydraulic function. These are mainly faults that result in shut-down oftheABS func- tionality.T hey trigger the transition to manual emergency mode. Dynamic braking is no longer possible unless only CAN faults occur affecting this functionality. 20 E70 Longitudinal Dynamics Systems • Shut-down level "electromechanical mode" (only EM F actuating unit) initiated by following DSC faults - DSC control unit fault - Electrical fault (e.g. wiring harness) - Sensorfault (brake light switch/wheel speed) - actuator fault/hydraulic unit - Bus communication fault • Shut-down level "electrohydraulic mode" (failure of EMF actuating unit) - Force sensorfault - Actuator fault of EM F actuating unit - Error in actuation electronics - Fault in actuating mechanism - Electrical fault • Shut-down level "total shut-down" - EMF control unit or controller fault -EMF button fault - Electrical fault, power supply Note: All fault codes are stored in the control unitin which the monitoring rou¬ tine was performed. The EMF control unit is informed of the fault status of the DSC control unit and vice versa. Fault Regeneration When a fault is detected, the system remains in a safe mode until the end of the "ignition ON" cycle, once reached, a shut-down level is not cancelled during the cycle. 21 E70 Longitudinal Dynamics Systems A shut-down status can only be cancelled when a corresponding check beforehand guarantees that the component previously detected as faulty is functioning correctly. Forthis reason, such component tests are also performed in shut-down mode.The fault information is retained in the fault code memory. The shut-down status is then cancelled when a new "ignition ON" cycle is started. If correct operation of the component cannot be determined after a fault, the parking brake will remain in the secure, shut-down state until the next workshop visit where the fault code can be deleted by the diagnostic unit after a repair. Monitoring and Fault Detection • Monitoring of electrical faults: Breaks (open circuits) and short-circuits with respect to ground and U-battof all cables leading to the control unit as well as short-circuits in the actuator or its cables are detected and dealt with accordingly. If possible, this also applies to short-circuits of neighboring connector pins. External breaks or short-circuits do not result in irreparable damage to the control unit. • Monitoring input signals: All input variables of the parking brake are monitored. In the event of a fault occur¬ ring, the complete system is shut down with a corresponding error message and fault code entry. • Monitoring EMF button: The EMF button has a redundant layout for diagnosis. The signal levels of this com¬ ponent are permanently monitored. In the event of a plausibility error, the complete system is shut down with a corresponding fault code entry. The DSC control unit also checks the plausibility of the signals from the EM F button. Signal level errors result in a corresponding fault code entry with partial shut-down. Dynamic braking is now no longer possible. • Monitoring vehicle speed signals: The parking brake system is totally shut down only when all 3 speed inputs have failed or are not available - The direct digital wheel speed signal, also known as the discrete speed signal, is permanently checked in terms of plausible signal edge change. - A mutual plausibility check of the reference speed made available from the DSC via the PT-CAN and the discrete speed signal is constantly performed. - The reference speed is the mean wheel speed from the DSC which is compared with the transmission output speed sent by the EGS. 22 E70 Longitudinal Dynamics Systems System Components. Hydraulic Unit with Add-on Control Index Explanation 1 Hydraulic unit with DSC control unit With its new pump concept, the hydraulic unit provides a significant improvement in control accuracy. 2x3 pump elements with a diameter of 6.5mm and intake-optimized units operate in the hydraulic unit. This pump concept ensures substantially improved pressure dynamics resulting in lower pedal feedback in ABS mode and higher control quality in HDS. Forthe driverthis is noticeable in as far as the pedal pulsation can now only be felt very slightly during ABS braking. There is a pressure sensor in the hydraulic unit. DSC Control Unit The DSC control unit can be replaced individually. The 47-pin connector connects the DSC control unit to the engine wiring harness. 23 E70 Longitudinal Dynamics Systems Volumetric Flow of Hydraulic Unit Index Explanation 1 Q [l/min] Liters per minute 2 t [s] at Q mean = constant A DSC8 B DSC E7x 24 E70 Longitudinal Dynamics Systems 25 E70 Longitudinal Dynamics Systems Hydraulic Diagram DSC E70 i L Index Explanation Index Explanation A Master brake cylinder D Front right brake B Rear right brake E Front left brake C Rear left brake 26 E70 Longitudinal Dynamics Systems Legend for Hydraulic Symbols X I 1 wv < Electrically operated hydraulic pump 2/2-way valve 2/2-way valve with non-return valve Outlet valve Hydraulic accumulator Filter Pressure sensor Non-return valve 27 E70 Longitudinal Dynamics Systems Wheel Speed Sensor 4 active wheel speed sensors are installed in the E70. All 4 sensors have a direct hard¬ wired connection to the DSC control unit. These active wheel speed sensors facilitate recognition of the direction of rotation, air gap (clearance) and standstill.The DSC control unit receives this information in the form of a PWM signal. 1 3 Index Explanation 1 Sensor ring/ferromagnetic wheel bearing seal carrier 2 1C sensorwith Hall sensor 3 Sensor housing Main Features of the Active Wheel Speed Sensor • Location recognition: Indicates whetherthe change in magnetic field strength can be guaranteed for cor¬ rect operation with a high degree of certainty. This signal is no longer required after approximately 20 km/h /12 mph. • Stationary recognition: The power supply is switched on if the wheel is stationary for more than 1 second. A signal is sent to the DSC control unit every 740ms so that the availability of the sensorcan be checked. • Speed signal: This is a frequency-dependent signal for determining the speed of the wheel. • Direction of rotation recognition: Indicates the direction of rotation, clockwise / counterclockwise. • Air gap reserve: Indicates whetherthe change in magnetic field strength is below the necessary value for correct operation. 28 E70 Longitudinal Dynamics Systems A two-wire line is used to transferthe signal .This two-wire interface is a combined earth and data line. The permanent magnet in the wheel speed sensor generates a magnetic field. The lines of the magnetic field run perpendicularto the sensor layer on the sensor element. The deviation of the fields lines caused by the increment wheel produces changes in resistance in the thin ferromagnetic layer of the sensor element. Function of Active Wheel Speed Sensor Index Explanation Index Explanation 1 Increment wheel 4 Permanent magnet 2 Electronic evaluation unit 5 M agnetic field lines 3 Signals from the wheel speed sensor 6 Sensorelement 29 E70 Longitudinal Dynamics Systems Steering Column Switch Cluster The Steering Column Switch Cluster (SZL) consists of the following components: • SZL electronics • Steering angle sensor • Steering column stalk, cruise control • Steering column stalk, direction indicator • Steering column stalk, wiper • Coil spring assembly The steering column switch cluster can only be replaced as a complete unit. The coil spring assembly is fitted on the steering column switch cluster. The spring coil assembly can be removed and replaced individually. Index Explanation Index Explanation 1 Steering column stalk, direction indicator 4 Steering column switch cluster with optical senor 2 Steering column stalk, cruise control 5 Steering column wiper stalk with buttons for rain/driving light/solar sensor 3 Code disc 30 E70 Longitudinal Dynamics Systems SZL Electronics The SZL electronics consists of a processor, the power supply and following interfaces: • F-CAN • Optical switches • Electrical switches The optical sensorfor measuring the steering angle is integrated in the pc-board of the control unit. Steering Angle Sensor The steering angle sensor is designed as a contactless, optical angle measuring system. The system consists of a code disc and an optical sensor. The code disc is connected by means of a driverto the steering wheel. The code disc turns within the optical sensor as the steering wheel is turned. Code Disc The code disc is black and features a line pattern.This pattern consists of two continuous lines on the outside and inside ofthe code disc. There are broken lines located at defined intervals between the two continuous lines.These lines repre¬ sent the digital area ofthe sensor. The digital code changes every 2°. The oblique lines in the outer zone representthe analogue area ofthe sensor. These lines permit precise measurement (0.1°) ofthe steering angle. 2 1 Index Explanation 1 Optical sensor 2 Code disc 31 E70 Longitudinal Dynamics Systems Optical Sensor The optical sensor is designed as follows: LED and fibre optics unitThe LED in connec¬ tion with the fibre optics unit has the task of projecting light from the top onto the code disc.The LED is soldered directly to the pc-board ofthe (SZL). The fibre optics unit is secured by means of two screws to the pc-board. Together, the LED with fibre optics unit and the line camera make up the optical sensor. Line Camera The line camera is located beneath the code disc. The line camera converts optical sig¬ nals that penetrate through the code disc into electrical signals. Index Explanation 1 Line camera 2 Fibre optics unit with LED Index Explanation 1 Fibre optics unit 2 Code disc 3 Steering column 4 Line camera 5 Output: Conversion to electrical signals 6 PC-board 7 Light-emitting diode 32 E70 Longitudinal Dynamics Systems DSC Sensor Index Explanation 1 DSC sensor The DSC sensor is located underthe front passenger seat and is available in two variants in the E70: • Vehicle without active steering, DSC sensor (designation M M 3.8), containing a - Transverse acceleration sensor. - Longitudinal acceleration sensor. - Yaw rate sensor in a housing. • Vehicle with active steering, DSC sensor (designation M M 3.2.2), containing. - 2 redundant transverse acceleration sensors. - Longitudinal acceleration sensor. - 2 redundant yaw rate sensors in a housing. 33 E70 Longitudinal Dynamics Systems Electromechanical Parking Brake (EMF) EMF Button On the E70, the EMF button orthe parking brake is located in the center console next to the gear selector lever. Index Explanation 1 EMF button The EMF button is based on the function logic of a hand brake. • Pull EMF button (1) up: Parking brake is activated • Press EMF button (1) down: Parking brake is deactivated Note: The indicator lamp in the instrumentclustershows the driver when the EMF is activated. 34 E70 Longitudinal Dynamics Systems Emergency Release Index Explanation 1 Bowden cable, emergency release EM F 2 Handle for emergency release The E70 tool kit is located in the luggage compartment which includes a red handle for the emergency release (2) of the EM F and the parking lock of the automatic gearbox. The EM F emergency release cable (1) is located on the rear left behind the side trim panel. 35 E70 Longitudinal Dynamics Systems Using the E70 EMF Emergency Release Index Explanation 1 Handle foremergency release 2 Bowden cable, emergency release EMF The opening in the handle forthe emergency release (1) is attached to the EM F emer¬ gency release cable as illustrated and the parking brake is released in the electromechan¬ ical actuating unit by pulling the handle upwards. 36 E70 Longitudinal Dynamics Systems Electromechanical Actuating Unit Index Explanation Index Explanation 1 Electrical connection 4 Bowden cable, rear left wheel 2 Bowden cable, rear right wheel 5 Bowden cable, emergency release 3 Component carrier On the E70, the EM F actuating unit is located on the component carrier (3) on the rear axle. 37 E70 Longitudinal Dynamics Systems Index Explanation Index Explanation 1 E M F control unit (control electronics) 8 Flexible band 2 Bowden cable, emergency release 9 Force sensor pc-board 3 Bowden cable, rear left wheel 10 Force sensor magnet 4 Lock pin 11 Bowden cable, rear right wheel 5 Actuating piston 12 Electrical connection 6 Spring 13 E M F control unit (control electronics) 7 Emergency release cable The EM F actuating unit is sealed watertight and the housing cannot be opened. The EM F actuating unit contains the following main components: • EM F control unit • Electric motor • Spindle gear mechanism • Force sensor The force sensor in the EM F actuating unit is a very important componentfor operation of the parking brake. With its signals, the force sensor makes it possible forthe EM F con¬ trol unit to determine the actuating force. The actuating force is essential for securing the required braking pressure. 38 E70 Longitudinal Dynamics Systems Force Sensor Index Explanation Index Explanation 1 Hook 5 Force sensor pc-board 2 Retaining plate 6 Piston 3 Hall-IC 7 Spring 4 Magnet 8 Lowersection of housing The housing ofthe force sensor consists of two halves.The lowersection of the housing (8) is made from pressure diecast aluminum so that it can take up the exerted forces. The upper section ofthe housing is made of plastic, to which the force sensor pc-board (5) with the Hall-IC (3) is secured. The magnet (4) is fixed to the piston (6). The force sensor is located between the left and right bowden cable assembly. During actuation, the piston (6) moves with the magnet against the spring (7). The travel range of spring compression is measured in accordance with the familiar Hall principle. Since the spring data are defined, the EM F control unit can calculate the applied force from the travel range and the spring data. The force sensor is calibrated at the end ofthe assembly line. 39 E70 Longitudinal Dynamics Systems Cruise Control with Brake Intervention (DCC) The operating and display philosophy on the DCC steering column stalk and in the instrument cluster in the E70 is the same as that in other model series. Functionally, the cruise control with brake intervention DCC is integrated in the DSC control unit. The DCC functionality is realized by way of communication with the partner con¬ trol units of the DSC control unit in the system network such as DM E/DDE, EGS, SZL and instrument cluster. Index Explanation 1 Button, select stored speed The DCC function can be activated from 30 km/h/19 mph (up to max. 250km/h/155mph) and is deactivated by similar factors as for cruise control: • Brake pedal actuation • Deactivation of DSC • Activation of DTC • Active DSC intervention • Deactivation by the driver • Speed is reduced below 22 km/h • "N" engaged • EM F function activated DCC achieves a deceleration of max. 2.1 m/s 2 and an acceleration of about. 1.7 m/s 2 . The transverse acceleration is variably limited by the Curve Speed Limiter (CLS).The primary emphasis has been placed on comfortable performance in this system configu¬ ration. When cruise control with brake intervention is activated, the brake lights are also activated in accordance with legal requirements in connection with a system related braking operation DCC. 40 E70 Longitudinal Dynamics Systems Extended functions of the DCC compared to a conventional cruise control system: • Active brake intervention to realize the set speed also when driving downhill • Curve Speed Limiter (CLS) - adaptation of driving speed when cornering (transverse acceleration). This function limits the maximum transverse acceleration dependent on vehicle speed with the aim of achieving the greatest possible agility in DCC mode. Driving on winding country roads in a speed range from > 50 km/h/31mph to < 120 km/h/74mph is controlled with a value of 3.3 - 3.7 m/s 2 .The value can increase up to 4.5 m/s forfast highway bends and slow lane changes at speeds between < 50 km/h/31mph and >120 km/h/74mph. • Comfort Dynamic System (CDS) - this enables a type of "manual throttle mode" on the steering column stalk. • Adapted downhill mode - the overrun fuel cutout and gear down shift are corre¬ spondingly adapted. 41 E70 Longitudinal Dynamics Systems Service Information Adjusting the Brake Shoes The procedure for adjusting the parking brake shoes is the same as before: Turn the adjusting screw using a screwdriverthrough the threaded hole in the wheel hub (10 teeth). Removing the Bowden Cable Assemblies Note: TheEMF must be set to service mode with the diagnostic tester before performing any maintenance orservice procedures (the parking brake cannot be applied, EMF assumes the outermost position). The EMF will not respond to an operating signal until service mode has been deacti¬ vated again. Necessary preparation: • To remove emergency release bowden cable assembly in luggage compartment (see Emergency Release). Use pointed pliers to press togetherthe white clip while pressing in the direction of the floor plate. Remove the wheels, brake calipers and brake discs (according to repair instructions) to expose the duo-servo brake shoes. The heat shield must be removed on vehicles with Active Roll Stabilization (ARS) and the ARS anti-roll bar lowered. (It is sufficient to release the ARS anti-roll bar at the mounting points and to lower it.) Unplug the electrical connectorfrom the EMF actuating unit. • To detach and expose the emergency release bowden cable assembly (Note: Clip fastening behind wheel arch panel). Release spring clip on wheel carrier. Detach nipple of cable assembly from brake show expander and pull the cable out of the wheel carrier. Release the cable assembly from the clip on the rear axle carrier and pull in the direction of the EMF actuating unit. • Detach the carrierforthe EMF actuating unitfrom the rear axle carrier and from the EMF actuating unit and pull out. • Screw the union nut on the rear left wheel cable assembly by 5-7 turns (left-hand thread) into the spline shaft of the actuator.Then fit the twist lock (square) of the threaded spindle in the guide in the actuator housing. The sleeve of the cable assembly must lie flat on the actuator housing before fitting the union nut. Tighten the union nut to 6 Nm. Attach the rear right wheel cable assembly to the mounting point on the actuator and secure with the clip. Make sure that the cable is firmly fit¬ ted. The cable assembly must lie flat on the actuator housing before fitting the union nut.Tighten to 6 Nm. 42 E70 Longitudinal Dynamics Systems • Reinstallation takes place in the reverse order of removal. Fit the new EMF actuating unit, cable assemblies first, in the package space. If it was necessary to slack off the carrierfrom the EM F actuating unit, it must be resecured to the EM F actuating unit and tightened to a torque of 4 ±0.5 Nm.The component carrier must be secured to the rear axle carrierto a torque of 19Nm±15 %. Before securing the cable assem¬ blies to the wheel carrier (tightening torque 8 Nm), check that the brake cables are securely attached in the brake shoe expander otherwise the EM F actuating unit may be damaged as soon as it is operated. Start-up A new EMF actuating unit is always setto "service mode".This mode can be actively reset with the diagnostic tester or it resets itself automatically on exceeding a defined vehicle speed. The actuating unit is now in "standby mode".The EM F actuating unit must then be encoded to the vehicle. Initializing the Parking Brake Note: The EMF must be initialized with the diagnostic tester after replacing the drum brake linings. Bedding in the Duo-servo Brake If the brake shoes of the duo-servo brake are replaced as part of repair or maintenance work, it is necessary to bed in the brake shoes before a sufficient holding effect may be achieved. Also in this case, the special routine must be activated in the EM F with the diagnostic tester. The flashing indicator lamp in the instrument cluster signals that the bedding-in program is ready. The bedding-in program will be aborted and the normal parking brake function resumed if the bedding-in is not started within 30 minutes of program activation or if the ignition is switched off. The bedding-in procedure can also be performed on the roller dynamometer. 43 E70 Longitudinal Dynamics Systems Function on Brake Rolling Dynamometer The Operation of the E70 parking brake can be tested on the brake rolling dynamometer. As part of the road inspection, the rear axle brake can be tested with the engine running by pulling the EM F button. As part of the road inspection, the rear axle brake can be tested with the engine running by pulling the EM F button. As a result, the EM F actuating unit is applied, the duo-servo brake is applied and the vehicle normally jumps out of the roller of the test rig. 44 E70 Longitudinal Dynamics Systems