ALTERNATORDual Circuit - Rectifier Plug TypeTESTING FOR SHORT IN ALTERNATOR SYSTEMDisconnect charging lead from battery, and connectcharge lead test lamp in series between battery andcharge lead. (Figure 169) DO NOT START ENGINE.Test lamp should not light. If it does light, stator charginglead is shorted or diode is defective. Disconnect chargelead connector at alternator. If test light does not go out,the lead from the cap to the battery is shorted. If lightgoes out, diode is defective.Fig. 169 - Testing for Short in Stator,Diode or Charge LeadTESTING DIODEDisconnect connector plug. Set meter on ohm scale.Check diode by attaching one meter lead to red statorlead wire. (A needle may be used to pierce stator leadwire insulation.) Touch the other meter lead to diode joinin plastic connector, then reverse meter leads. Themeter should show a reading in one direction only. Ifmeter shows a reading in both directions or does notshow a reading in either direction, the diode is defectiveand the connector assembly must be replaced. See Fig.170.Fig. 170 - Testing DiodeNOTE: Service replacement diodes are pre-assembledto a connector and a short lead wire for ease ofinstallation.TESTING STATOR CHARGING COILSRemove blower housing, flywheel etc. and examine redlead wire for cuts, damaged insulation or obvious shorton lead. If bare spots are found repair with electricaltape. If short cannot be repaired, replace stator. Statorshould also be checked for continuity as follows:Use VOA meter set on ohm scale. Touch one meterlead to stator laminations, touch the other meter lead tored stator charge lead wire. (Pierce red wire insulationwith a needle to insure meter lead contact.) Meter shouldshow continuity. Fig. 171.Next remove screw which attaches stator ground wiresto stator laminations. Be certain ground wire does nottouch laminations as shown in Fig. 171 and repeatprevious test. Meter should not show continuity. If meterdoes not show continuity in first test or shows continuityduring second test, stator is defective and must bereplaced.Fig. 171 - Testing StatorNOTE: Discoloration of stator coils does not mean statoris defective. A shorted diode will pass battery currentthru stator coils to ground, which discolors coils due toheat. Replacing diode would normally restore alternatorwithout replacing stator.53
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