Table of Contents E60/E61 xDrive with DSC8+ Subject Page xDrive with DSC 8+ . ....4 xDrive .5 DSC8+.5 System Circuit Diagram .6 System Components .9 ATC 300 Transfer Case.10 DSC8+Control Unit.12 Bus Overview .12 Principles of Operation.13 Power Flow .13 DSC/DSC8+Control Unit.14 Dynamic Stability Control .15 ASC-X/ADB-X.15 Hill Decent Control (HDC).16 Dry Braking .17 Brake Standby.18 Automatic Soft Stop .19 Fading Compensation.20 Drive-off Assistant .21 Service Information.22 Oil, Transfer Case, and Clutch Monitoring.22 Oil .22 Transfer Case and Clutch .22 Diagnosis .23 Programming (flashing).23 Warning Indicator Lamps .23 Initial Print Date: 03/05 Revision Date: 04/05 Subject Page E60/E61 xDrive with DSC8+ Model: 525xi, 530xi, 530xiT Production: From April 2005 After completion of this module you will be able to: • Familiarize yourself with DSC8+features • Explain the xDrive mechanical operation • Describe the xDrive power flow 3 E60/E61 xDrive with DSC8 + xDrive with DSC8+ Note: This section only contains changes to xDrive forthe E60, 61, 90,91. Detailed information on xDrive is covered in the E83/E 53 xDrive module. From 04/2005, the BMW 5 Series wagon and sedan (optional) will have all wheel drive capability utilizing the tried and tested all-wheel drive system xDrive of the X3 and X5. The innovative all-wheel xDrive is a system for controlling and regulating the "infinitely" variable drive torque distribution overthe front and rear axle. The xDrive uses the system functions of the DSC to positively influence the vehicle handling by specifically distribut¬ ing the power in the event of understeer or oversteer. With the controlled multi-disc clutch in connection with the xDrive it is now possible to resolve the conflict between traction and vehicle handling. This is been achieved in that the xDrive does not predefine the torque distribution by a fixed transmission ratio as is the case with the previous systems. Instead, distribution of the drive torque is dependent on the clutch lockup torque of the controlled multi-disc clutch in the transfer case and on the transmitted torque at the front and rear axle. Driver Benefits In addition to the previous functions, a series of additional safety and comfort functions will now be available to the driver with the introduction of the DSC8+in the E60/E61. The expanded DSC8+functions include: • Dry braking • Brake standby • Automatic soft-stop • Fading warning and assistance • Drive-off assistant • Hill descent control HDC Besides the outstanding chassis characteristics ofthe BMW 5 Series, the all wheel drive system offers traction advantages not only on snow and ice but also on unsurfaced roads. Note: Because many system components and functions and are shared between the xDrive and DSC 8+ system, they will be discussed together in this section. 4 E60/E61 xDrive with DSC8 + x Drive The innovative xDrive four-wheel drive is a system that controls and regulates the distrib¬ ution of driving torque to the front and rear axles. The measured variables of DSC are used by xDrive but are also influenced by modified handling performance. The multi-disc clutch is the heart of the xDrive. By using the controlled multi-disc clutch, it is possible to resolve the conflict between traction and handling performance. This is achieved through the fact that torque distribution is not determined by a fixed gear ratio in the xDrive as was the case in the previous systems. Instead, the distribution of dri¬ ving torque is dependent on the locking torque of the controlled multi-disc clutch in the transfer case and on the transferable torque to the front and rear axles. DSC8+ The DSC8+system adds features to the DSC8 system already in use in the E60 sedan and combines features used in other DSC systems (E53/83). Due to the mechanical composition of the xDrive system, the programming for DSC regulation has also been changed. Present DSC 8 functions: • ABS Anti-lock Braking System • ADB Automatic Differential Brake • EBV Electronic Braking Force Distribution • CBC Cornering Brake Control Present DSC functions: • TCC Transfer Case Control (control of multi-disc clutch in transfer case) • ASC-X Automatic Stability Control X (special function for all-wheel drive vehicles) • ADB-X Automatic Differential Brake X (special function for all-wheel drive vehicles) • HDC Hill Decent Control New DSC/DSC8+functions • Dry braking • Brake standby • Automatic soft stop • Fading assistance • Drive-off assistant • Trailer stabilization control • Hill descent control HDC ASC Automatic Stability Control DSC Dynamic Stability Control DBC Dynamic Brake Control MSR Engine Drag Torque Control 5 E60/E61 xDrive with DSC8 + System Circuit Diagram E60/E61 xDrive with DSC8 + System C ircuit Diagram Legend Index Explanation 1 Instrument cluster 2 Outside temperature sensor 3 Safety and gateway module (SGM) 4 Steering column switch cluster (SZL) with HDC button 5 Electronic transmission control module (EGS) 6 Transfer case control unit (VGSG) 7 Temperature sensor 8 Electronic motor, actuator drive 9 Coding resistor 10 Motor position sensor 11 Accelerator pedal module (FPM) - (not for US) 12 Digital motor electronics (DM E) control unit 13 Wheel speed sensor, front right 14 Handbrake switch 15 Dynamic traction control (DSC8+) 16 Wheel speed sensor, rear right 17 Brake wear sensor, rear right 18 Wheel speed sensor, rear left 19 DSC button 20 Center console switching center (SZM) 21 Controller (CON) 22 Brake light switch (BLS) 23 Brake wear sensor, front left 24 Brake fluid level sensor 25 Wheel speed sensor, front left 26 CCC orM-ASK 27 Central information display 28 Yaw rate/longitudinal/transverse acceleration sensor (Y-sensor-2) 29 Rain light sensor (RLS) 30 Car Access System (CAS) 7 E60/E61 xDrive with DSC8 + 8 E60/E61 xDrive with DSC8 + System Components The xD rive/DSC 8+ system is composed of the following major components: • ATC 300 transfer case • Adjusting levers • Servomotor with motor position and temperature sensor • Coding/classification resistor • Transfer case control unit DSC8+control unit Wheel speed sensor Index Explanation Index Explanation 1 Oil Pan lead through 4 Propeller shaft to front axle 2 Right drive shaft, front 5 Front axle differential 3 Transfer case 6 Left drive shaft, front 9 E60/E61 xDrive with DSC8 + ATC 300 Transfer Case The transfer case ATC 300 (Active Torque Control) is used on the E60/E61. In view of the restricted package space of the transmission tunnel in the BMW 5 Series, it was not possible to adopt the transfer case from the BMWX3 (ACT400)with the same torque rating. On the BMW 5 Series it was not possible to drive the forward power flow diagonally as is the case on the X3 with a chain, but rather it is necessary to divert it L-shaped with the aid of spur gears (pinions), resulting in a modified design of the transfer case. The actuator drive and the actuation of the control lever were also modified. The clutch package remains unchanged. The forward connection is provided by a bolted on drive shaft. The flange of the ATC transfer case is the same for automatic and manual transmissions. Index Explanation Index Explanation 1 Propeller shaft to front axle 8 Clutch housing 2 Drive flange to front axle 9 Output flange to rear axle 3 Control cam 10 Propeller shaft to rear axle 4 Transfer case 11 Disc package 5 Idler gear 12 Actuator drive 6 Drive gear 13 Drive pinion 7 Control lever 14 Output gear 10 E60/E61 xDrive with DSC8 + The ATC 300 is installed in the E61 and E60 all wheel drive models.The ATC 400 is installed in the E83 and the ATC 500 in the E53 M U. The ATC 300 differs from the other transfer cases because it is gear driven not chain driven. The basic functions and operations remain unchanged. The difference between the transfer cases are: • ATC 400 & 500 are chain driven vs. ATC 300 which is gear driven • ATC 300 & 400 uses a four bolt flange to connect to the front propeller shaft vs. ATC 500 which uses a splined connection • ATC 500 utilizes one more disc in the multi-disc clutch than the ATC 300 & 400 • ATC 500 has 19mm greater length between the input shaft and the output shaft to the front axle than the ATC 400. (the ATC 300 uses gears not a chain) ATC 500 Transfer Case Index Explanation Index Explanation 1 Input from manual / automatic transmission 5 Clutch discs 2 Output to rear axle prop, shaft 6 Adjusting levers with ball ramp 3 Output to front axle prop, shaft 7 Chain 4 Servomotor 8 Disc cam 11 E60/E61 xDrive with DSC8 + DSC8+Control Unit The DSC8+control unit is installed in the engine compartment essentially consists of three components: • Add-on control unit • Valve block with integrated pressure sensors • Pump motor The newly developed changeover valves permit even more exact control in the low pres¬ sure range, resulting in the following advantages: • Reduction of control noise • Improvement in control quality and control comfort • Improvement in automatic brake intervention by the active/dynamic cruise control AC C/DC C • Improvement in the control accuracy of the HDC function • Realization of additional brake functions Bus Overview The transfer case control unit(VGSG) is on the PT-CAN. VGSG shares information with DSC for overall xDrive control and has diagnostic communication. E MG EMC LM lltL r_:in 1 J [HArt ! K ms nr I A |\I1M |j„ CAJZ I 5MFA EHC CCC ■DDC s-iuD W rai TOP-MPi ULF TfAFA S FZ SB FA HJSft 'f.SU* f IMBF SZL \Hy, DKG BKP DDE — E13E AufTuFA - *LiV6F - ACC 1 EMBF ZH f.-CJiK .■ii-ivVi;..'..- UQST Ul* ■HKA 0 PT-C AM == f-ClM eled LaTAH Bus Topology Chart of E61 Sports Wagon (530xiT) 12 E60/E61 xDrive with DSC8 + Principles of Operation Power Flow When the multi-disc clutch in the transfer case is disengaged, no driving torque is trans¬ mitted to the front axle. All of the driving torque is then distributed to the rear axle. This is because the input shaft (1) is splined providing a permanent connection to the rear axle propeller shaft output flange (2).The multi-disc clutch couples the rear axle propeller shaft output flange to the front propeller shaft output (3). The driving torque on the front axle is increased or decreased by regulating the locking pressure of the multi-disc clutch, providing a stepless coupling of the front axle to the drivetrain.This depends on driving situations and road conditions. When the multi-disc clutch is fully engaged, the front and rear axles turn at the same speed. Driving torque distribution (front/rear) is based on available traction at each axle. For example, when traction is identical on the front and rear axles and a driver accelerates from a stop in first gear at full throttle, the rear axle is capable of sustaining greater driving torque as the vehicle weight shifts from the front to the rear. Another example is when the front axle is on a high traction surface and the rear axle is on ice. In this case, virtually 100% of the available driving torque is transmitted to the front axle. Based on available traction, virtually no driving torque can be supported by the rear axle . Obviously, when more driving torque is transmitted to the front axle, driving torque on the rear axle is proportionally reduced due to lack of traction. *5 Color Explanation Red Torque from engine to rear axle Green Controlled torque to front axle Dark Blue Rotation to drive multi-disc clutch 13 E60/E61 xDrive with DSC8 + DSC/DSC8+Control Unit As in the earlier DSC control units, there are two microprocessors incorporated in the add on DSC8+control unit. The difference is that in the DSC8 and DSC8+both processors do not calculate the same algorithms but rather one processor is responsible for perform¬ ing control and monitoring calculations and checking the plausibility of the wheel speeds. There are also two semiconductor relays integrated in the DSC8+control unit, one for the pumpmotorand the other for the solenoid valves. On exceeding a road speed of 6 km/h, an electronic self-test is started, during which the pump motor and all solenoid valves are briefly actuated. If the brake is operated at a dri¬ ving speed of 6 km/h, as may be the case with "two-foot drivers", the self-test will be per¬ formed at a speed of 15 km/h. The check of the wheel speed signals is already started at a speed of 2.75 km/h. In connection with the xDrive, the DSC 8+control unit also undertakes the task of calcu¬ lating the lockup torque for the multi-disc clutch in the transfer case. The lockup torque is always optimally set and controlled to suit the corresponding driving situation. The drive torque distribution over the front and rear axles is based on the lockup torque. The lockup torque to be set is derived from the pilot control and from a higher-ranking traction and vehicle dynamics regulator corresponding to the driving situation. The DSC8+control unit sends the data, concerning the lockup torque, on the PT-CAN to the transfer case control unitVGSG. Conversely, the transfer case control unit signals the lockup torque actually set as well as the load on the transmission fluid, electric motor and multi-disc clutch. 14 E60/E61 xDrive with DSC8 + Dynamic Stability Control DSC8+offers several new features from April 2005 production vehicles. They are: • ASC-X/ADB-X • Hill descent control HDC • Dry braking • Brake standby • Automatic soft stop • Fading assistance • Drive-off assistant • Trailer stabilization control ■ ASC-X/ADB-X Unlike regular road vehicles, SAVs are also meant to demonstrate satisfactory handling characteristics and appropriate traction on unconventional roads. In order to provide opti¬ mum propulsion with sufficient cornering stability on both normal roads and other road surfaces, Automatic Stability Control X (ASC-X) contains a detection function to distin¬ guish between them. When off-road terrain is detected, wheel slip threshold is increased to provide sufficient traction force with the increased levels of traction loss. ASC-X is supplemented by the Automatic Differential Brake (ADB-X) function, which applies the brakes to the wheels per axle, for side to side torque transfer. For example, when a wheel is spinning on one side (up to the slip setpoint), the brakes are applied to that wheel and the driving torque is transferred through the axle differential to the wheel with the higher traction. This provides superb capabilities when there are diagonal trac¬ tion losses (ie. left front/right rear). ADB-X remains active when DSC is deactivated. Furthermore, ADB-X can develop full capability because the engine power is not reduced, even during extreme four wheel drive operation. Only that wheel which has a low traction receives the brake application. The brake disc can overheat with excessive ADB-X intervention with DSC deactivated. In this situation, the operation is discontinued at a disc temperature of approx. 700 2 C and is resumed when this temperature drops below approx. 400 2 C. This is a calculation per¬ formed by the DSC control unit based on brake application time, pressure, wheel speed, etc. 15 E60/E61 xDrive with DSC8 + Hill DecentControl (HDC) As on previous all wheel drive vehicles in the BMW line, the E61 all-wheel drive also fea¬ tures the hill descent control facility for safe vehicle operation on steep downhill inclines. The HDC stabilizes the vehicle and prevents the wheels locking.The DSC8+module controls the build-up of braking pressure at all four wheels so that the vehicle drives downhill at a speed of approx. 7.5 mph (12 km/h). The HDC function is activated in the central information display via the menu: Settings => Vehicle settings =>HDC The HDC ON function can be activated by setting a tick in the menu and deactivated by removing the tick. Furthermore, the HDC ON/OFF function can be selected with one of the two free but¬ tons (asterisk, hash) in the steering wheel button menu. < HDC ► p HDC ein CD 01-12 Vi+ ..ill 10:16 Menu HDC ON / Active 16 E60/E61 xDrive with DSC8 + Dry Braking The water spray produced in wet conditions coats the brake discs with a waterfilm, caus¬ ing delayed response of the brakes. In connection with previous systems it was therefore recommended to operate the brakes from time to time. The dry braking function is dependent on the position of the wiper switch and therefore on the signal of the rain/lights sensor. The brake discs are kept dry by lightly applying the brake pads cyclically as required, this achieving improved braking response in wet condi¬ tions. While doing so, the pressure in the brake system is increased by approx. 1 bar and the brake pads are applied for approx. 1.5 seconds. Dry braking takes place underfollowing conditions: • Driving speed >70 km/h • Continuous wipe operation in stage 1 or 2 The repeat interval depends on the wiper stage: • Continuous wipe stage 1 - 200 s • Continuous wipe stage 2 - 120 s • Generally 90 s as from 09/2005 This applies only when the driver himself does not apply the brake during this time. The driver notices no deceleration or noise. Left disc with waterfilm before dry braking Right brake disc after dry braking 17 E60/E61 xDrive with DSC8 + Brake Standby Quick release of the accelerator pedal causes the brake pads to be applied against the brake disc thus reducing the stopping distance (by approx.. 30 cmAOO km/h) during emergency braking. The DSC module builds up slight brake pressure (approx. 2.5 bar) temporarily (approx. 0.5 seconds) in order to eliminate the clearance between the brake pad and brake disc by applying the brake pads. The brake standby function is activated under following conditions: • Driving speed >70 km/h • M inimum time between brake application 8 s • The brake standby function is not activated in connection with sudden acceleration (sports driving style). The DM E/DDE control unit makes available the signal indicating quick release of the accelerator pedal via the PT-CAN. The sensitive driver may perceive a slightly harder brake pedal. No delay or noise is dis¬ cernible forthe driver. Index Explanation P Braking pressure in Bar T Time in milliseconds 1 Pilot pressure applied by driver 2 Braking pressure progression with brake standby 3 Braking pressure progression without brake standby 18 E60/E61 xDrive with DSC8 + Automatic Soft Stop Due to the transition from sliding friction to static friction on the brake disc, a stopping jolt occurs when braking to a standstill where the occupants perceive an increased feeling of deceleration. When braking lightly (< 25 bar) at constant pressure to bring the vehicle to a halt, the soft stop function automatically reduces the braking pressure at the rear axle just before the vehicle comes to a stop. This consequently reduces the positive acceleration peak per¬ ceived by the occupants by approx. 50% while extending the action time. The speed and standstill status are recognized by way of the wheel speed sensors. i Q.S IjO -1,5 2.0 2,5 [ 6 ] Index Explanation m/s ^ Deceleration s Time in seconds Red Deceleration without soft stop Blue Deceleration with soft stop -50% Reduction of occupant deceleration Note: This function is inactive at medium to high deceleration or in the event of ABS control in order notto lengthen the stopping distance. 19 E60/E61 xDrive with DSC8 + Fading Compensation High temperatures (>550°C) can occur at the brake discs when driving downhill over long periods or as the result of extreme multiple braking operations ( >80 bar). These high temperatures cause a change in the coefficient of friction of the brake pads resulting in the braking effect diminishing (fading). For this purpose, the temperature of the brake disc is calculated by means of a tempera¬ ture model contained in the DSC8+software. The braking pressure applied by the driver is measured by the delivery pressure sensor and compared with the current vehicle deceleration (target/actual value). When the braking effect diminishes, the fading compensation provides assistance for the driver in that pressure is additionally built up by the DSC module. Brake Disc with Fading 20 E60/E61 xDrive with DSC8 + D ri ve-off A ss ista nt When negotiating uphill gradients, the drive-off assistant holds the vehicle for a short time (approx. 1.5 s) after releasing the brake so that the vehicle drives off comfortably without the need to use the handbrake. The braking pressure required by the driver to hold the vehicle is maintained automatically in the system. When driving off, the braking pressure is not reduced before the torque is sufficient for the vehicle to drive off. The holding pressure in the brake system (10 to max. 70 bar) is dependent on the uphill gradient. Uphill gradients are detected by the DSC sensor with the aid of a longitudinal accelera¬ tion sensor. The function is active both when driving forwards (transmission in Drive) and when reversing (transmission in Reverse) on uphill gradients (up to 50 %). Drive-off Assistant Function 21 E60/E61 xDrive with DSC8 + Service Information Safety Notice!!! On a vehicle equipped with an automatic transmission, when driving onto brake analyzers, move the selector leverto the "N" position . On a vehicle equipped with a manual transmission, do not release the clutch pedal once on the brake analyzer. This keeps the transfer case clutch open and the vehicle cannot be pulled off the analyzer. Towing: Use only a flatbed carrierfor all xDrive vehicles! Oil, Transfer Case, and Clutch Monitoring ■ Oil All xDrive transfer cases use Shell Gearoil part number83 22 0 306 816. There is no scheduled service for the transfer case oil. Oil Monitoring is performed by the VTG control module to determine when a service (change) is due.The VTG calculates transfer case and clutch wear based on the amount of slip, engagement pressure (torque), speed and mileage. This calculation accounts for: • normal "dry" road driving (Integrator 1) • "adverse" road driving (Integrator 2) • "other" road extreme driving (Integrator 3) Depending on individual vehicle use - driving styles and driving conditions, the transfer case oil service interval will vary. When a service is due, this will be indicated by a Fault Code and additional details are available using the DISplus/ GT1. Service functions provide directions on changing the transfer case oil and updating the VTG control module with the necessary reset and adaption procedure. This is extremely important for CBS. Transfer Case and Clutch The transfer case and clutch have separate monitoring characteristics. These values are stored as adaptive values in the VGSG control unit and must be transferred to a new con¬ trol unit if replaced. The value for both can be obtained using the diagnostic software under: Control Unit Functions =>VTG => Diagnosis requests =>Transmission Control Unit Functions =>VTG => Diagnosis requests =>Clutch 22 E60/E61 xDrive with DSC8 + Diagnosis Diagnosis is available forfault repairs and service procedures using the DISplus/GTl. The test plan forthe VGSG contains valuable information on: • Replacing control unit • Replacing transfer case • Transferring adaptation values - Automatic - Manual • Reading out adaptation values Programming (flashing) Both the transfer case control unit (VTG) and the DSC control unit are programmable and the new control unit(s) must be programmed when replaced. The wear values stored in the VTG control module (to be replaced) must be transferred to the replacement VTG. Warning Indicator Lamps The warning indicator lamps forthe xDrive/DSC are found in the instrument cluster as shown on the bottom of this page. The warning indicator lamps and acoustic signals (gong) are assigned to the xDrive / DSC system states of malfunction described on the next two pages. 23 E60/E61 xDrive with DSC8 + Check Control Messages Relating to xDrive/ DXC8+ Fixed Variable Check control Information in central information display indicator indicator message lamp lamp DSC disabled! You have disabled DSC. Restricted vehicle stability while accelerating and cornering. DTC enabled, DTC enabled. DSC restricted! Dynamic traction control DTC increases forward propulsion on unpaved surfaces, however, it decreases vehicle stability. DSC failed! Drive with moderation DBC failed. No additional braking assistance from DBC in emergency braking situations. Drive with moderation. Have checked by your BMW dealer as soon as possible. DSC failed! Drive with moderation Control systems! Drive with moderation Control systems! Drive with moderation Brake pads! Replace Brake fluid! Stop cautiously Brakes too hot! Allow to cool down DSC failed. Restricted vehicle stability while accelerating and cornering. Drive with moderation. Have checked by your BMW dealer as soon as possible. Brake and vehicle control systems failed. Reduced braking and vehicle stability. Avoid abrupt braking where possible. Have checked by nearest BMW dealer. Brake and vehicle control systems failed. Drive with moderation, avoid abrupt braking where possible. Have checked by nearest BMW dealer. The brake pads are worn. Have replaced by nearest BMW dealer. Brake fluid level too low. Reduced braking efficiency. Stop cautiously. Contact nearest BMW dealer. Brakes too hot Critical temperature as a result of permanent heavy load. Danger - reduced braking efficiency. Allow brakes to cool down. Stop if necessary. 24 E60/E61 xDrive with DSC8 + Check Control Messages Relating to xDrive/ DXC8+ (cont'd) Fixed Variable Check control indicator indicator message lamp lamp Brakes overheated! Allow to cool down 4x4 system and DSC failed! 4x4 system defective! Drive with moderation 4x4 system, DSC and ABS failed! 4x4 System, DSC, ABS and emergency EBV failed! HDC enabled! HDC disabled! No HDC control! Drive slower HDC currently not available! Information in central information display Brakes overheated Critical temperature exceeded. Braking efficiency no longer guaranteed. Stop at the next opportunity and allow to cool down substantially. 4x4 system and DSC failed! Vehicle stability restricted. Drive with moderation. Have checked by your BMW dealer as soon as possible. 4x4 system defective Vehicle stability restricted. Drive with moderation. Have checked by your BMW dealer as soon as possible. 4x4 system, DSC and ABS failed! Vehicle stability restricted. Drive with moderation. Have checked by your BMW dealer as soon as possible. 4x4 System, DSC, ABS and emergency EBV failed! Vehicle stability restricted. Drive with moderation. Have checked immediately by your BMW dealer. HDC disabled. Hill descent control HDC is disabled at speed above 60 km/h (37 mph). System can be re-enabled at speed below 35 km/ h (22 mph). HDC not possible! Control range ends at 35 km/h (22 mph). To use HDC, reduce speed accordingly. HDC not available. Automatic brake intervention interrupted for safety reasons as brakes are overheated. Shift down and drive carefully in order to reduce temperature. AB5 ABS O Drive-off Drive-off assistant inactive assistant Caution, vehicle can roll back! Have checked by (©) inactive! your BMW dealer at next opportunity. BRAKE BRAKE m Li BRAKE Electronics fault! Stop cautiously Central vehicle electronics failed. Continued journey not possible. Contact nearest BMW dealer. 25 E60/E61 xDrive with DSC8 +