Alternator To Battery Continuity Test

NOTE: Check alternator wiring harness connections and drive belt tension and ensure battery is fully charged before performing test.

Turn ignition off. Disconnect negative battery cable. Remove output lead from alternator terminal "B". See Fig 1. Install a 100-amp or 130-amp ammeter in series with terminal "B" and disconnected output lead. Install positive lead of ammeter to terminal "B" and negative lead to disconnected output wire.

Fig 1: Identifying Alternator Terminals (Typical)
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
Install a digital voltmeter between alternator terminal "B" and positive battery terminal. Install positive voltmeter lead to terminal "B" and negative lead to positive battery terminal. Reconnect negative battery cable.
Start and operate engine at 2500 RPM. Turn accessories on and adjust engine speed until ammeter indicate slightly greater than 30 amps, and note voltmeter reading. If voltmeter indicates .3 volt or less, system is okay.
If voltage is greater than .3 volt, check wiring between alternator terminal "B", fusible link and positive battery terminal. If terminal is not sufficiently tight or if harness is discolored due to overheating, repair as necessary and retest.