Regulated Voltage Test - Mitsubishi Electric Lancer Evolution-VII Workshop Manual

REGULATED VOLTAGE TEST

Ignition
switch
Battery
This test determines whether the voltage regulator
is correctly controlling the alternator output voltage.
(1) Always be sure to check the following before
the test.
Alternator installation
D
Check that the battery installed in the
D
vehicle is fully charged.
(Refer to GROUP 54 - Battery.)
Alternator drive belt tension
D
(Refer to GROUP 11 - On-vehicle Service.)
Fusible link
D
Abnormal noise from the alternator while
D
the engine is running
(2) Turn the ignition switch to the "LOCK" (OFF)
position.
(3) Disconnect the negative battery cable.
(4) Use the special tool (Alternator test harness:
MB991519) to connect a digital voltmeter
between the alternator S terminal and earth.
(Connect the (+) lead of the voltmeter to the
"S" terminal, and then connect the (−) lead of
the voltmeter to a secure earth or to the battery
(−) terminal.)
(5) Disconnect the alternator output wire from the
alternator "B" terminal.
ENGINE ELECTRICAL -
Ammeter
MB991519
Black
Voltmeter
Red
Engine-ECU
Charging System
Load
B
FR
Alternator
L
S
G
Blue
Yellow
(6) Connect a DC test ammeter with a range of
0 - 100 A in series between the "B" terminal
and the disconnected output wire. (Connect
the (+) lead of the ammeter to the "B" terminal.
Connect the ( - ) lead of the ammeter to the
disconnected output wire.)
(7) Reconnect the negative battery cable.
(8) Connect a tachometer or the MUT-II. (Refer
to GROUP 11 - On-vehicle Service.)
(9) Turn the ignition switch to the ON position and
check that the reading on the voltmeter is equal
to the battery voltage.
NOTE
If the voltage is 0 V, the cause is probably
an open circuit in the wire or fusible link between
the alternator "S" terminal and the battery (+)
terminal.
(10)Turn all lamps and accessories off.
(11)Start the engine.
(12)Increase the engine speed to 2,500 r/min.
(13)Read the value displayed on the voltmeter when
the alternator
becomes 10 A or less.
16-7
output current alternator