Fault36:48VoltKeyswitchUndervolt–
Starter/Generator
InfoCenterDisplay:
____FAULT#36____
48VKEYSWITCH
UNDERV
Important:Forthisfault,theterm“keyswitch”referstothe48Vlogicpowercircuit,nottothe
ignitionswitch.
FaultDescription
Thisfaultisreportedwhenthe48Vsystemvoltagedropsbelow36Vatthestarter/generator(S/G).
CircuitDescription
Allcircuitsonthe48Vbusaresuppliedwithsteady48Vsignal.Thisiscalledlogic,orkeyswitchpower.
RecommendedServiceActions
Step1:Verifythatthefaultrepeats.
1.ClearthesystemfaultsfromtheInfoCenter.RefertoClearingFaultsfromtheInfoCenter(page19).
2.Operatethemachine.
Pass
Thefaultdidnotrepeat.GotoReturningtheMachinetoService(page21)andfollowthestepslisted.
Note:Ifthefaultdoesnotrepeat,anisolatedeventhasoccurred.
Fail
Thefaultrepeated.GotoStep2.
Step2:Checkall48Vfuses.
1.Removeeach48Vfuseandtestthemindividually.
2.Installeachfuseaftertesting,makingsureitisproperlyseated.
3.Verifythatthefaultrepeats.
Pass
Thefaultdidnotrepeat.GotoReturningtheMachinetoService(page21)andfollowthestepslisted.
Fail
Thefaultrepeated.GotoStep3.
Step3:CheckthelogicpowerconnectiontotheS/G.
1.UsingtheInfoCenter,bringuptheDIAGNOSTICSscreen.
2.SelecttheGENERATORmenu,andscrolltotheINPUTsignal.
3.Verify35–65Varebeinginputtothegenerator.
Pass
Thelogicpowerconnectionisgood.GotoStep4.
Fail
Thelogicpowerconnectionisnotgood.Repairorreplacethefaultywiring.GotoReturningthe
MachinetoService(page21)andfollowthestepslisted.
130