124OPERATION
PrecautionsWhenInstallingElectricalEquipment
Connectingelectricallypoweredorelectricallycontrolledequipmenttothevehiclemay
causeinterferencewithothervehiclecomponents(e.g.,theABSsystem).Theamountof
interferencewilldependontheoperatingfrequencyofanynewsignalsandthedegreeto
whichtransientsignalsarecoupledintothevehiclesystem.
Note:Whenevernewelectricalequipmentisinstalled,itistheobligationoftheinstaller
toensurethatthenewequipmentdoesnotinterferewiththeproperoperationofallother
electricalsystemsonthevehicle.
Ifnewelectricalequipmentisinstalled,avehiclecheckoutprocedureshouldbeperformed.
1Performthecheckoutprocedureunderthefollowingconditions:
•Enginerunning
•Brakesystemairpressureinoperatingrange
•Vehiclestationary
•Brakepedalfullydepressed
2Operatethenewequipmentunderallstarting,runningandshutdownconditions.
3ListenforsignsofairexhaustingfromABSmodulatorvalves(whichisanindicationof
aninterferencecondition).
4Correctallinterferenceconditionsbeforeoperatingthevehicle.
Note:Thecenterpinofthestandardseven-pintrailerelectricalconnectorhasbeen
standardizedasthededicatedconnectionforuninterruptedpowerfortrailerABS.This
pinisalwayshotwhenthetractorignitionisturnedon.
DANGER
Sometrailersmanufacturedpriortothe
trailerABSregulationsmayusethecenter
pintopowercertaintrailerauxiliary
equipment.Thepossibilityexiststhatthis
auxiliaryequipmentmaybeunexpectedly
activatedbythetruckortractorelectrical
system,resultinginpersonalinjuryor
damagetoequipment.Cautionmustbe
usedwhenconnectingthetrailerelectrical
connectortoensurethatpowertothe
centerpinwillnotunintentionallyactivate
anytrailerauxiliaryequipment.
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