System Diagnosis - Charging System

Fig. 2 Charging Circuit Wiring Diagram.:

During normal system operation, the indicator lamp, if equipped, will illuminate until the engine is started. If the indicator lamp operates abnormally, or an overcharged or undercharged battery condition exists, the following procedure should be used to diagnose the charging system. Refer to charging circuit wiring diagram, Fig. 2, when diagnosing the system.

1. Ensure alternator drive belt is tight and in good condition.
2. On models equipped with a charge indicator lamp, proceed as follows:
a. Observe indicator lamp with ignition on and engine not running.
b. If lamp does not light, disconnect electrical connector from alternator and ground L terminal.
c. If lamp lights, replace alternator assembly. If lamp does not light, locate and repair open circuit between ground and ignition switch.
d. Observe indicator lamp with engine running at idle.
e. If lamp lights, disconnect electrical connector from alternator and observe lamp.
f. If lamp goes out, replace alternator assembly. If lamp remains lit, locate and repair ground in L terminal wire.
3. If battery is overcharged or undercharged, proceed as follows:
a. Disconnect electrical connector from alternator.
b. With ignition on and engine not running, connect a voltmeter between ground and terminal L, then terminal I (if used), measuring voltage at each terminal.
c. If voltmeter indicates zero voltage at either terminal, locate and repair open in circuit. If voltmeter indicates battery voltage, proceed to step d.
d. Reconnect alternator electrical connector, then measure voltage across battery with engine running at idle and all accessories off.
e. If voltage reading is more than 16 volts, replace the alternator. If voltage reading is less than 16 volts, proceed to step f.
f. Connect an ammeter to alternator output terminal, turn accessories on, then load battery with a carbon pile to obtain maximum amperage.
g. While maintaining 13 volts or more, note amperage reading. If reading is within 15 amps of rated output, the alternator is satisfactory. If reading is not within 15 amps of rated output, replace the alternator. Refer to Starting and Charging / Charging System / Alternator / Service and Repair.