Service manual

G420F(FE) Service Manual Chapter 4. Engine Electrical System 132
Drop of Electric Pressure Test of Alternator
Output Wire
This test is to check that wiring is correctly
connected between the alternator “B“ terminal and
battery (+) terminal.
Preparation
1. Turn the ignition switch OFF.
2. Disconnect the battery ground cable.
3. Disconnect the alternator output wire from the
alternator “B” terminal.
4. Connect a DC ampere meter (0-100A) between
the terminal and the disconnected output wire.
Connect (+) lead wire to the terminal “B” and (-)
lead wire to the disconnected output wire.
NOTE: In case of using a clamp type ammeter, it is
possible to measure current without disconnecting
the harness.
5. Connect a digital voltmeter between the alternator
“B” terminal and the battery (+) terminal.
Connect (+) lead wire to the terminal and (-) lead
wire to the battery (+) terminal.
6. Connect the battery ground cable.
7. Be sure that the hood is opened.
Test
1. Start the engine.
2. Repeating ON and OFF of headlight and small
light, adjust the engine speed until an ammeter
reads 20A and at that time measure voltage.
Result
1. If voltmeter reading is within the standard, it is
normal.
Test voltage Maximum 0.2V
2. If voltmeter reading is more than the standard,
mostly wiring is faulty. In this case, inspect wirings
between the alternator and the battery (+) terminal
as well as between the alternator “B” terminal and
the fusible link.
3. Also prior to re-test, check and repair the
connecting part for looseness and the harness for
discoloration by overheating.
4. After test, adjust the engine speed at idle and turn
the light and ignition switch OFF.
5. Disconnect the battery ground cable.
6. Disconnect the ammeter and voltmeter.
7. Connect the alternator output lead wire to the
alternator “B” terminal.
8. Connect the battery ground cable.
Output Current Test
This test is to check that the alternator output
current is identified with the rated current.
Preparation
1. Prior to test, inspect the following items and repair
if necessary.
1) Be sure that the battery installed in the vehicle
is normal.(See “Battery”)
NOTE: When measuring output current, necessarily
use a slightly discharged battery. Fully charged
battery is not enough to use for correct test owing to
insufficient load.