Service manual

G420F(FE) Service Manual Chapter 4. Engine Electrical System 128
Troubleshooting
Charging system defect is almost caused by lack of
pan belt tension and faulty function of wiring,
connector, and voltage regulator.
One of most important thing during troubleshooting
of charging system is determining the reason
between overcharging and lack of charging. So,
prior to inspection of alternator, check the battery for
charging. Faulty alternator causes the following
symptoms.
1. Faulty battery charging
1) IC regulator fault(Short circuit)
2) Field coil fault
3) Main diode fault
4) Auxiliary diode fault
5) Stator coil fault
6) Brush contact fault
2. Overcharging : IC regulator fault(Short circuit)
Other faults such as voltage adjusting problem
except above symptoms rarely happen.
Refer to the following troubleshooting table
Symptom Possible cause Remedy
Fuse cut off Replace
Bulb burnt out Replace
Loose wiring connection Retighten
With ignition
switch ON,
charging
warning lamp
does not
illuminate
Bad connection of L-S terminals
Inspect and replace wiring,
Replace voltage regulator
Loose or worn drive belt Correct or replace
Fuse cut off Replace
Fuse link cut off Replace
Faulty voltage regulator or alternator Inspect alternator
Faulty wiring Repair
With the
engine started,
warning lamp
is not turned
off (Battery
needs often
charging)
Corrosion or wear of battery cable Repair or replace
Faulty voltage regulator (Charging warning lamp illuminates) Replace
Overcharged
Voltage detection wring fault Replace
Loose or worn drive belt Correct or replace
Loose wiring connection Retighten
Short circuit Repair
Fusible link cut off Replace
Ground fault Repair
Faulty voltage regulator (Charging warning lamp illuminates) Inspect alternator
Battery is
discharged
Battery out Replace