OperationoftheABSsystem
Awheelspeedsensorismountedtoeachofthe
fourwheels.Ifwheellock-upofeitherofthe
frontwheelsortherearwheelsissensedduring
braking,thebrakepressureisadjustedautomat-
icallyuntilthewheelnolongerslips.Thebrake
pressureisregulatedforeachfrontwheelindi-
viduallyandforbothoftherearwheels
together.
Onaroadsurfacewhichisslipperyononlyone
side,therearwheelwhichisbrakingontheslip-
perysurfacedeterminesthebrakepressure
whichwillbeappliedequallytobothrearwheels.
Thisensuresthatdirectionalstabilityismain-
tained.However,ifbrakingforcesapproachthe
wheellock-uppointforallwheels(panicbraking)
theABSsystemwillintervenetoprovidearapid
rythmicbraking.
TheproperoperationofABSisperceivedbythe
driverasapulsatingbrakepedalinconjunction
withaudiblenoiseandperhapssomevibration.
I>Ifyouexperiencethesesensationswhiledriv-
ingoraroadsurfacewithquestionabletrac-
tion,reducevehiclespeedappropriateforthe
prevailingroadconditions.
Thefunctionalreadinessofallthemainelectrical
componentsoftheABSischeckedbyanelec-
tronicmonitoringsystembothbeforeandwhile
youdrive.
8
WarninglightUSA
@
WarninglightCanada
WhentheignitionisswitchedontheABSwarn-
inglightwilllightupwhilethesystemiselec-
tronicallyinterrogatedandgoesoutwhenthe
engineisstartedifthecheckisnotyetcom-
plete.
IftheABSwarninglampfailstogoout,thisindi-
catesthatABShasbeendeactivatedduetoa
fault.Ifthewarninglightsintheinstrumentpanel
andon-boardcomputerlightupwhileyouare
driving,thisindicatesthatafaulthasoccurred.
Inbothcases,normalbraking,asinvehicles
withoutABS,isstillretained.
TheABSsystemshould,however,beexamined
atanauthorizedPorschedealerimmediatelyto
preventtheoccurrenceoffurtherfaults.
I>IftheABSsystembecomesinoperative,take
yourvehicletoyourauthorizedPorsche
dealerimmediately.
/!\Warning!
ThecontrolunitoftheABSbrakesystemis
setforstandardtiresize.Ifnon-standard
tiresareinstalled,thecontrolunitmaymis-
interpretthespeedofthevehicle,because
ofthevariantdataitreceivesfromthesen-
sorsontheaxles.
I>Useonlytiremakesandtypestestedby
Porsche.
Controls,Instruments
57
