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Onboard power supplyBattery master / isolation rely E74Battery isolationIn a crash, the battery is isolated from the starterlead via the battery master switch. This preventsa short circuit in the starter lead which could leadto a fire.Battery master / isolation switchSight-glassReset switchThe isolation signal is received by the batterymaster switch from the airbag control unit J234via a separate signal wire.Recognition of isolationIf the battery has been isolated, a white coverwill be seen in the sight-glass instead of a copperwinding. The relay should then be reset using thereset switch, otherwise starting the engine will notbe possible.If the onboard power supply has a twin batteryconcept, the onboard power supply control unitchecks the position of the battery master switch.If the master switch is on, starting the vehicleusing the starter battery will be prevented.S298 017Electrical circuitJ285J234VKeyABCE74J234J285TVVBatteryStarter motorAlternatorBattery master / isolation switchAirbag control unitDash panel insertcable distributorOnboard consumersTVTVE74BCAS298 040Before resetting, the starter lead must be checked for short circuits. For this reason, resettingshould only be carried out by a specialist workshop.18

The electrically folding towing deviceTrailer recognition control unitActivation conditionsIn addition to normal actuation of the lights onthe trailer, the control unit also controls activationof the folding tow hitch.- Terminal 15 off- Terminal 15 on androad speed 0 km/h and engine offOperation is via the control buttons in theinterior.The tow hitch is unfolded by an electric motorwith a Hall sender and the procedure ismonitored by the control unit. If the tow hitchencounters an obstacle, the unfolding procedureis stopped. For this purpose, the control unitmonitors the power drawn by the motor.If the control button is actuated repeatedly,the unfolding procedure can be continued.Electrical circuitL76K211K212Conditions for switching offThe following conditions could lead to the foldingprocedure being stopped: Overload recognition as protection againstentrapmentThe folding procedure will be stopped if thereis a change in the power supply, i.e. if thevoltage drops below 9 Volt or rises above15 Volt for more than 300 msChange in the conditions that permit activationS298 041KeyJ345G470E474K211K212L76Trailer detection control unitTow bar coupling motor Hall senderButton for electrically folding tow hitchTow hitch folding out warning lampTow hitch folding in warning lampSwitch illumination19

Battery conceptThe equipment with batteriesOverviewThe Volkswagen Touareg can be fitted withdifferent battery systems.The following derivatives are possible:- Single battery electrical system- Single battery electrical system with secondbattery to supply additional water heater- Twin battery electrical system for V10 TDIengineSingle battery electrical systemSingle battery electrical systemVehicles with a single battery electrical systemdraw the power required for the onboard powersupply and the starter from this one battery.BatteryS298 009Single battery electrical system withadditional batteryThe second battery supplies the additional waterheater with power and is charged when theengine is running via a charging circuit relay.20

Dual battery electrical systemTo ensure that the power required for starting is always available on vehicles with V10 TDI engines,a twin battery electrical system is fitted.In this electrical system, one battery, the starter battery, has the role of supplying the starter with powerand, if necessary, also the electrical consumers required for the starting procedure (start-up consumers).The second battery, the onboard power supply battery, provides the rest of the electrical consumers withpower.The batteries are switched in parallel to provide the necessary current to start the V10 TDI engine.Dual battery electrical systemOnboard power supplybatteryStarter batteryS298 01021

Battery conceptDual battery electrical systemOnboard power supply structure of twinbattery electrical systemTo prevent the starter battery from becomingdischarged by electrical consumers, theconsumers are split into two categories:- Start-up consumers(e.g. glow plug system, engine control unit)- Onboard consumers(e.g. radio, heated rear window)Stand-byThe system is on stand-by when the onboardpower supply control unit is in sleep mode(terminal S not active).If on stand-by, relay 1 for voltage supply J701and second/starter battery charging circuit relayJ713 are open.Relay 2 for voltage supply J710 is closed.The start-up consumers and the remainingelectrical consumers are supplied from theonboard power supply battery.Via the relay for start-up consumers, these canbe supplied from the starter battery. Consumersthat require a large amount of energy, such asthe glow plugs on diesel engines, are alwayssupplied from the starter battery.Stand-by switch positionIn addition, both batteries can be connected viathe additional/starter battery charger relay tocharge the starter battery.The actuation of the relays comes from theonboard power supply control unit. It monitorsthe voltage of both batteries when the vehicle isin motion and can thus detect when the starterbattery needs recharging.HVBJ623J624SVCBVBV22

Starting proceduresWhen the ignition is switched on, the onboardpower supply control unit J519 is activated(wake-up mode) and evaluates the charge statusof the batteries. If the voltage reading of theonboard power supply battery is below 10.5 Volt,it is deemed to be discharged. The starter batteryis deemed to be discharged if the voltagereading is below 11.5 Volt.J581J518A1J701J713J519There are four different conditions that can bedetected before the engine is started dependingon the charge status of the batteries:- Onboard power supply and starter batterycharged- Onboard power supply battery discharged,starter battery charged- Onboard power supply battery charged,starter battery discharged- Onboard power supply and starter 01J710J713BVSVHVJ710Onboard power supply battery, batteryAdditional battery, starter batteryStarterAlternatorBattery master / isolation switchEntry and start authorisation control unitOnboard power supply control unitRelay for parallel switching of batteriesEngine control unitEngine control unit 2Voltage supply relay 1Voltage supply relay 2Charger relay for additional and starterbatteryOnboard power supply consumersStart-up consumersHT consumersE74AS298 05323

Battery conceptStart procedure with charged onboard power supply battery and starter batteryStart-up is in the normal relay switch position (stand-by). The charging circuit relay for the additional andstarter battery J713 and voltage supply relay 1 J701 are open. Voltage supply relay 2 J710 is closed.The battery parallel circuit relay J581 is activated by the entry and start authorisation control unit in thesame way as terminal 50.Switch position with charged onboard power supply battery and starter BVABVS298 015KeyAA1BCE74J518J519J581J62324Onboard power supply battery, batteryAdditional battery, starter batteryStarterAlternatorBattery master / isolation switchEntry and start authorisation control unitOnboard power supply control unitBattery parallel circuit relayEngine control unitJ624J701J710J713BVSVHVEngine control unit 2Voltage supply relayVoltage supply relay 2Charging circuit relay for additional battery(starter battery)Onboard consumersStart-up consumersHT consumers

Start procedure with discharged onboard power supply battery and charged starter batteryThe start-up consumers are switched from the onboard power supply battery to the starter battery.To prevent voltage compensations between the two batteries, voltage supply relay 2 J710 is opened firstand after about 100 milliseconds, voltage supply relay 1 J701 is closed. The second battery chargingcircuit relay J713 remains open. In this case, the vehicle cannot be opened using the radio remote control.Because the onboard power supply control unit detects a discharged onboard power supply batterywhen the ignition is switched on, an emergency start is activated.Switch position with discharged onboard power supply battery and charged starter BVABVS298 016The information is sent to the dash panel insert and the control unit for entry and start authorisation viathe emergency mode cable connection. In the display of the dash panel insert, the warning message"Please start engine" will then be shown. If the onboard power supply control unit detects that thealternator is charging the batteries when the engine is running, the onboard consumers will be switchedto the onboard power supply battery. The emergency start procedure is then complete. Only now, usingthe automatic gearbox selector lever, is it possible to select a gear and drive the vehicle. If the ESPwarning lamp lights up, it will go out after the vehicle is set in motion when the steering angle sensor isrematched. Glow plug operation is inhibited, the glow plug system warning lamp will flash.25

Battery conceptStart procedure with charged onboard power supply battery and discharged starter batteryThe relay is in the same switch position as with starting procedures when both batteries are charged.The charging circuit relay for the additional and starter battery J713 and voltage supply relay 1 J701 areopen. Voltage supply relay 2 J710 is closed.Switch position with charged onboard power supply battery and discharged starter BVABVS298 043KeyAA1BCE74J518J519J581J62326Onboard power supply battery, batterySecond battery, starter batteryStarterAlternatorBattery master / isolation switchEntry and start authorisation control unitOnboard power supply control unitBattery parallel circuit relayEngine control unitJ624J701J710J713BVSVHVEngine control unit 2Voltage supply relay 1Voltage supply relay 2Second battery charging circuit relay(starter battery)Onboard consumersStart-up consumersHT consumers

Starting procedure with weak starter battery and onboard power supply batteryIf the voltage of the onboard power supply battery is less than 10.5 Volt and the voltage of the starterbattery is less than 11.5 Volt, the voltage of both batteries is calculated following activation of theonboard power supply control unit wake-up mode.If during this calculation, the starter battery voltage is found to be greater than that of the onboardpower supply battery, the start procedure for discharged onboard power supply battery is selected.If the onboard power supply battery has the greater voltage reading, the start procedure is actuatedwithout change in the relay switch position.Switch position at high starter battery BVABVS298 016KeyAA1BCE74J518J519J581J623Onboard power supply battery, batterySecond battery, starter batteryStarterAlternatorBattery master / isolation switchEntry and start authorisation control unitOnboard power supply control unitBattery parallel circuit relayEngine control unitJ624J701J710J713BVSVHVEngine control unit 2Voltage supply relay 1Voltage supply relay 2Second battery charging circuit relay(starter battery)Onboard consumersStart-up consumersHT consumers27

Power supplyAlternatorDrive layoutThe drive layout of the alternator on the V10 TDIengine consists of a sprocket configuration,a range-change gear with a ratio of 3.6:1 anda Hardy disk.The alternator is cooled via the engine coolingcircuit to protect it against overheating, which inturns ensures improved longevity and efficiency.The range-change gear increases the workingspeed of the alternator, which thereby improvesperformance. This is necessary to provide thelarge amount of voltage required by theelectrical system, even at idling speed.AlternatorCoolant connectionsHardy diskRange-change gearSprocketconfigurationS298 04828

ChargingCharging of the starter and onboard power supply batteryThe onboard power supply battery is charged continuously. The starter battery is charged via the secondbattery/starter battery charging circuit relay J713. This is actuated by the onboard power supply controlunit J519. The normal charging time is 20 minutes. After this period the relay will open. If the starterbattery voltage drops below 12.8 Volt, a new charging cycle of 20 minutes maximum is started.While the glow plugs are active, the relay stays closed.If voltage supply relay 1 J701 does not open after the engine has been started because the contacts aresticking for example, the charging circuit relay J713 will close after four minutes until the ignition isswitched off.The onboard power supply derives its power from both batteries which are connected in parallel andprotected against overload by relay J701.Switch position for CBVABVS298 018KeyAA1BCE74J518J519J581J623Onboard power supply battery, batterySecond battery, starter batteryStarterAlternatorBattery master / isolation switchEntry and start authorisation control unitOnboard power supply control unitBattery parallel circuit relayEngine control unitJ624J701J710J713BVSVHVEngine control unit 2Voltage supply relay 1Voltage supply relay 2Second battery charging circuit relay(starter battery)Onboard consumersStart-up consumersHT consumers29

Onboard power supply managementThe onboard power supply control unit J519Functions of onboard power supply controlunitUntil now control units and relays functioned atdifferent locations in the vehicle. In the onboardpower supply control unit, these functions arenow localised.Onboard power supply control unitThe onboard power supply control unit in theTouareg is responsible for the followingfunctions: Load managementParking lightDipped beam headlightsSide lightsTurn signals (not in exterior mirrors)Main beam headlightsAdditional main beam headlightsFog lightsFootwell lightsTerminal 58dIndicator lamp for hazard warning lightsRelay for headlight washer systemFuel pump priming actionHornTwin washer pumpInterior lightsRain and light sensor voltage supplyFurthermore, the following switches and signalsare processed and sent via the CAN bus to othercontrol units. 30Bonnet contact switchExterior mirror adjustment switchHazard warning lights buttonLight switchVoltage supply at starter and onboard powersupply batteryS298 012

Fitting locationThe onboard power supply control unit can befound in the vehicle interior on the driver's sideunder the dash panel in the footwell.It is connected to the E-box in the same way asthe entry and start authorisation control unit.Fitting location of onboard power supply controlunit and entry and start authorisation control unitEntry and startauthorisation control unitE-box under dash panelOnboard powersupply control unitS298 019Load managementFurthermore, the onboard power supply control unit deactivates convenience system consumers andlong-term HT consumers e.g. heated rear windscreen, so that heavy discharging of the battery isavoided. If the onboard power supply is placed too much under load, the idling speed is also increased.This ensures that there is always sufficient energy to start the engine. Switching off is inline with theguidelines for the Volkswagen Phaeton and is described in Self-Study Programme 272.31

Onboard power supply managementPriming function of electrical fuel pumpCrash shut-offThe petrol engines of the Volkswagen Touareg allfeature a priming function of the fuel pump sothat enough pressure in the fuel lines can be builtup.If with the ignition switched on a crash isdetected, a signal is sent from the airbag controlunit J234 via the CAN bus and the fuel pump isswitched off immediately. After about 5 secondsit can be activated again by switching theignition off and on.Function:When the driver's door is opened and terminal15 is closed, a signal is sent via the CAN bus fromthe entry and start authorisation control unit J518(terminal 15 off), a signal is also sent from thedriver's door control unit J386 (driver's dooropened) and, for reasons of safety, a discreetsignal (status of terminal 15) is sent to theonboard power supply control unit J519. This thenactuates the relay to prime the fuel pump forapprox. 2 seconds. The priming function of thefuel pump is stopped when the ignition isswitched on. Continued actuation is donethrough the engine control unit.Electric circuitJ518J386Discreetsignal fromterminal 15CAN busJ519If the driver's door stays open, the actuation isrepeated a maximum of three times in intervals.J623J17Timed actuation from the onboard power supplycontrol unit prevents continued actuation of thefuel pump if the driver's door is opened andclosed a number of times in short intervals.G6S298 021KeyG6J17J386J518J519J62332Fuel pumpFuel pump relayDriver's door control unitEntry and start authorisation control unitOnboard power supply control unitEngine control unit

Interior light actuationThe interior lighting is actuated by the onboardpower supply control unit. The voltage supplycomes from terminal 30G.Terminal 30G is activated under the followingcircumstances:- the interior light switch is actuated,- the ignition is switched on,- the vehicle is unlocked, a door, the bonnet orthe tailgate is opened,- the bonnet contact switch.To prevent discharge of the vehicle battery whenthe interior lights are switched on, power supplyfrom terminal 30G is interrupted in the followingcircumstances:- the ignition is switched off,- the vehicle is locked from the outside and alldoors are locked.Data 86J387J388J389J519WInterior light switchAirbag control unitDash panel insert (Gateway)Driver door control unitFront passenger door control unitRear left door control unitRear right door control unitOnboard power supply controlunitInterior lightsWFS298 022If a crash is detected, the interior light is switched on immediately. After the ignition is switchedon and off and after is has been switched on again, the cut-off function from terminal 30G isreactivated.33

Onboard power supply managementThe function M32U1U9BatteryIgnition switchLight switchHazard warning light switchLight regulator for lightingswitches and instrumentsExterior mirror adjustment switchMirror adjustment change-over switchHeadlight range control adjusterExterior mirror heating buttonMirror fold system switchRear fog light buttonFog light buttonGlove box buttonInterior light button, frontDriver reading light buttonFront passenger reading light buttonAnti-theft alarm/vermin repellent system contact switchStowage compartment illumination switchRain sensorHigh tone hornLow tone hornRelay for headlight washer systemInterior light switch-off delay blocking diodeInterior lightingSide light bulb, leftSide light bulb, rightTurn signal bulb, front leftTurn signal bulb, front rightDipped beam bulb, leftMain beam bulb, leftDipped beam bulb, rightMain beam bulb, rightCigarette lighterCigarette lighter, rearSignal outputGNDSi

a network via a CAN bus system. Due to reasons of safety and because the data bus systems work at different rates of transfer, the control units are allocated to different CAN bus systems. If one data bus system should fail, the others can continue to function. The CAN bus systems are separated as follows iar Tevi-Dr n CAN bus, C,eNA bscuneine-Cvno