Starter and Alternator Troubleshooting & Diagnostics

1 1your Ultimate Fleet SolutionStarter and AlternatorTroubleshooting & Diagnosticsprovided by: Diesel USA Group get more at: System TroubleshootingStarting System TroubleshootingStarting problems may be electrical ( , faulty switch) ormechanical ( , faulty ring gear, wrong engine oilviscosity).System problems, their possible cause and the actionrequired to correct them by: Diesel USA Group get more at: System Troubleshooting ChartStarting System Troubleshooting ChartSymptomPossible CauseCorrective ActionEngine willnot crankDead batteryCheck battery state ofcharge. Recharge ifpossible. Replace ifnecessaryMelted fusible linkReplace fusible linkLoose connectionsClean and tightenconnectionsKey switch or start switchcontacts in poor conditionPolish contacts if possible,replace switch as necessarySolenoid hold-in coil coil open or solenoid or starterSolenoid contacts worn awayReplace solenoid or starterMechanical problem in engineCheck engineprovided by: Diesel USA Group get more at: System Troubleshooting ChartStarting System Troubleshooting ChartEnginecranks tooslowly tostartWeak batteryCheck battery.

2 Recharge ifpossible. Replace ifnecessaryLoose or corrodedconnectionsClean and tightenconnectionsFaulty starterTest Starter , Replace ifnecessaryImproper engine oil viscosityor problem with engineChange oil. Check engineStarterspins, butengine willnot crankFaulty over-running clutchCheck over-running clutch,replace Starter if necessaryDamaged or worn starterpinion gear or engine gears for damage orwear. Replace Starter or ringgearSymptomPossible CauseCorrective Actionprovided by: Diesel USA Group get more at: System Troubleshooting ChartStarting System Troubleshooting ChartSymptomPossible CauseCorrective ActionStarter doesnot engage /disengageproperlyFaulty Starter solenoid,Test Starter . Replace ifnecessaryDamaged or worn starterpinion gear or engine ring gearCheck gears for damage orwear.

3 Replace Starter or ringgearStarter doesnot stoprunningKey switch, start switch orstarter relay contacts keepclosing or faulty componentOver-running clutch sticks toshaftReplace starterprovided by: Diesel USA Group get more at: SystemStarting SystemSystem Voltage Loss Test1. Adjust load to be 500 A. Record VB Adjust load to 500 A. Record Subtract (-) VM fromVB. Loss not toexceed Proceed to positive &negative loss tests iftotal loss KS provided by: Diesel USA Group get more at: SystemStarting SystemCable Voltage Loss Tests1. Adjust load to 500 A. Record +V Adjust load to 500 A. Record Add +V and Total loss not toexceed or replacecable with excessiveloss.+V-V KS provided by: Diesel USA Group get more at: Circuit Voltage LossRelay Circuit Voltage Loss1.

4 Disconnect KS terminal from Starter relay as Connect load tester and voltmeter as Turn on key switch, press start button. Listen for relay to load to 100 Record SR1 ( Starter relayvoltage loss) reading. Loss not to exceed to next tests ifloss exceeds specs. KS TerminalSR1provided by: Diesel USA Group get more at: Circuit Voltage LossRelay Circuit Voltage Loss1. Connect load tester as illustrated (same as previous test)2. Turn on key switch, press start button. Adjust load to 100 Connect volt meter to test points as illustrated. Record voltage reading at SR2,SR3 and Add readings SR2 and equals relay wirevoltage loss. Loss not to exceed or replace wirewith excessive SR4 (Relay Contact) not toexceed V. Replace relay ifloss exceed KS Terminalprovided by: Diesel USA Group get more at: Circuit Voltage LossRelay Circuit Voltage Loss1.

5 Disconnect KS terminal wire2. Turn key switch on, press start Connect voltmeter to test points SR5 Record voltage readings at specified test points. Add all readings. Total notto exceed V. Repair orreplace defective KS Terminalprovided by: Diesel USA Group get more at: System TroubleshootingCharging System TroubleshootingPrecautions Do not operate the Alternator with its B+ terminal disconnected. Do not disconnect the battery while the Alternator is rotating. Never ground the Alternator B+ terminal, It has battery voltage at all times. Never use a Mega-Ohm tester on an Alternator . Never expose the Alternator to by: Diesel USA Group get more at: System Troubleshooting ChartCharging System Troubleshooting ChartSymptomPossible CauseCorrective ActionIndicator lampdoes not lightwith keyswitch on1.

6 Blown fuse2. Lamp burned out3. Wiring connections loose4. Defective relay5. Defective regulator1. Check charge, Ignitionand Engine fuses, replaceas Replace lamp3. Tighten looseconnections4. Check relays, if used, forcontinuity and properoperation5. Replace regulator oralternatorprovided by: Diesel USA Group get more at: System Troubleshooting ChartCharging System Troubleshooting ChartSymptomPossible CauseCorrective ActionBatteries notcharging1. Insufficient belt tension2. Defective battery(s) or batteryconnections3. Blown fuse or fusible link4. Defective wiring5. Faulty alternator6. Excessive electrical load1. Tighten or replace2. Check battery(s0 andbattery terminalconnections3. Check fuse and fusiblelink;replace as needed4. Check voltage drop5. Replace alternator6. Reduce load by turningoff all unnecessaryaccessoriesprovided by: Diesel USA Group get more at: System Troubleshooting ChartCharging System Troubleshooting ChartSymptomPossible CauseCorrective ActionConstantlyovercharging(batteryelec trolyte isdepleted in ashort time)BatteryPoor contact at voltage detectionpoint of alternatorFaulty voltage regulatorFaulty battery; replaceClean contact areaReplace regulator oralternatorTighten or replaceReplace alternatorInsufficient belt tensionFaulty bearingAbnormalNoiseprovided by: Diesel USA Group get more at: SystemCharging SystemSystem Voltage Loss1.)

7 Adjust load to rated Alternator VB (Battery Voltage) Adjust load to rated Alternator VA ( Alternator Voltage) Subtract VA( Alternator Voltage)from VB (BatteryVoltage). Loss not to Proceed topositive and negativecable loss tests ifloss exceeds by: Diesel USA Group get more at: SystemCharging SystemCable Voltage Loss Test1. Adjust load to rated Alternator +V (Positive Cable Loss) Adjust load to rated Alternator V (Negative Cable Loss) reading. Loss not to or replacecable with excessiveloss.+V-Vprovided by: Diesel USA Group get more at: TechnologyNew TechnologyThe DENSO Starter does not generate thesame amount of heat as our protection not by: Diesel USA Group get more at.