ELECTRICAL EQUIPMENT - Q.4TEST 4Check of Alternator OutputDisconnect battery earth cable, and connect testammeter between the alternator main terminal anddisconnected cables. Reconnect battery earthcable, and switch on the full electrical load and leaveon for 3 or 4 minutes. Leave load on and startengine and run at approximately 2000 rev/min. Thealternator output should balance the load, and at thesame time show a charge to the battery.Check Warning Light ControlIf warning light does not function either by remaining"on" or "off", but the system is charging satisfactorily,connect voltmeter between the alternator "AL"terminal and earth. Reading should be 7.0-7.5 max(12 volt alternator) or 14.0-15.0 (24 volt alternator).Connect leads 'E' and 'WL' together. If warning lamplights the warning light control is faulty and shouldbe replaced.6.Fault Diagnosis Procedure for 11 ACAlternator Fails to Charge(a) Check driving belt for correct tension and wear.(b) Apply Tests 1 and 2.Low-Unsteady Charging Rate(a) Check driving belt for correct tension and wear.(b) Check for high resistance at battery terminals and inthe circuit wiring and connection. Check allconnections made to earth.(c) Apply Test 2.Flat Battery or Low State of Charge(a) CHECK condition of battery with hydrometer andhigh rate discharge tester.(b) Check driving belt for correct tension and wear.(c) Check that the field isolating relay contacts openwhen master switch is off; otherwise battery willdischarge through rotor winding.(d) Check that flat or low battery is not caused byinsufficient alternator output caused by abnormalelectrical loads by applying Test 4.Excessive Charge Rate to a Fully Charged Battery(a) Apply Test 3.Noisy Alternator(a) Alternator loose in mounting brackets.(b) Worn, frayed or loose drive belt.(c) Worn bearings, fully out of alignment.(d) Rotor damaged or pulley fan loose on shaft.(e) Open circuited, or short circuited rectified diodes, orstator winding open-circuit.(f)Loose pulley.
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