There are three types of alternator failures: short, open
(wire burned out), or loss in rotor magnetism. A short or
open in one of the coil wires will result in either a low output,
or no output at all. A loss in rotor magnetism, which may be
caused by dropping or hitting the alternator, by leaving it
near an electromagnetic field, or just by aging, will result in
To check the alternator output voltage, do the following
Turn off the ignition switch.
Remove the fuel tank (see Fuel System chapter).
Supply fuel to the throttle body with an auxiliary fuel tank.
Disconnect the alternator lead connector [A].
Connect the hand tester [B] as shown in the table 1.
Start the engine, and run it 6 000 rpm 5 minutes.
Run it at the rpm given in the table 1.
Note the voltage readings (total 3 measurements).
Table 1 Alternator Output Voltage
Tester (+) to
Tester (–) to
ELECTRICAL SYSTEM 16-31
@ 4 000 rpm