Content .. 345 346 347 348 ..

Mitsubishi Lancer Evolution IX. Manual - part 347

CHARGING SYSTEM

ENGINE ELECTRICAL

16-5

ON-VEHICLE SERVICE

ALTERNATOR OUTPUT LINE VOLTAGE DROP TEST

M1161000900681

AK203361AE

Alternator

Ammeter (clamp-type)

Voltmeter (digital-type)

"B" terminal

Battery

This test determines whether the wiring from the
alternator "B" terminal to the battery (+) terminal
(including the fusible link) is in a good condition or
not.
1. Always be sure to check the following before the

test.

• Alternator installation

• Drive belt tension

(Refer to GROUP 11A

− On-vehicle Service

P.11A-7

• Fusible link

• Abnormal noise from the alternator while the

engine is running.

2. Turn the ignition switch to the "LOCK" (OFF)

position.

3. Disconnect the negative battery cable.
4. Connect a clamp-type DC test ammeter with a

range of 0

− 100 A to the alternator "B" terminal

output wire.
NOTE: The way of disconnecting the alternator
output wire and of connecting the ammeter is pos-
sibly not found the problem that the output current
is dropping due to the insufficient connection
between terminal "B" and the output wire.

5. Connect a digital-type voltmeter between the

alternator "B" terminal and the battery (+)
terminal. [Connect the (+) lead of the voltmeter to
the "B" terminal, and then connect the (-) lead of
the voltmeter to the battery (+) cable].

6. Reconnect the negative battery cable.
7. Connect the M.U.T.-II/III.
8. Leave the hood open.
9. Start the engine.
10.With the engine running at 2,500 r/min, turn the

headlamps and other lamps on and off to adjust
the alternator load so that the value displayed on
the ammeter is slightly above 30 A.
Adjust the engine speed by gradually decreasing
it until the value displayed on the ammeter is 30
A. Take a reading of the value displayed on the
voltmeter at this time.

Limit: maximum 0.3 V

NOTE: When the alternator output is high and the
value displayed on the ammeter does not
decrease until 30 A, set the value to 40 A. Read
the value displayed on the voltmeter at this time.
When the value range is 40 A, the limit is maxi-
mum 0.4 V.

11.If the value displayed on the voltmeter is above

the limit value, there is probably a malfunction in
the alternator output wire, so check the wiring
between the alternator "B" terminal and the
battery (+) terminal (including fusible link).
If a terminal is not sufficiently tight or if the
harness has become discoloured due to
overheating, repair and then test again.

CHARGING SYSTEM

ENGINE ELECTRICAL

16-6

12.After the test, run the engine at idle.
13.Turn off all lamps and the ignition switch.
14.Remove the M.U.T.-II/III.

15.Disconnect the negative battery cable.
16.Disconnect the ammeter and voltmeter.
17.Connect the negative battery cable.

OUTPUT CURRENT TEST

M1161001000692

AK401826

Alternator

Ammeter
(clamp-type)

Voltmeter

Battery

Ignition switch

Engine-ECU

Load

–

Charge warning
lamp

This test determines whether the alternator output
current is normal.
1. Before the test, always be sure to check the

following.

• Alternator installation

• Battery (Refer to GROUP 54A − Battery −

On-vehicle Service

P.54A-5

NOTE: The battery should be slightly discharged.

The load needed by a fully-charged battery is
insufficient for an accurate test.

• Drive belt tension

(Refer to GROUP 11A

− On-vehicle Service

P.11A-7

• Fusible link

• Abnormal noise from the alternator while the

engine is running.

2. Turn the ignition switch to the "LOCK" (OFF)

position.

3. Disconnect the negative battery cable.

CAUTION

Never use clips but tighten bolts and nuts to con-
nect the line. Otherwise loose connections (e.g.
using clips) will lead to a serious accident
because of high current.
4. Connect a clamp-type DC test ammeter with a

range of 0

− 100 A to the alternator "B" terminal

CHARGING SYSTEM

ENGINE ELECTRICAL

16-7

5. Connect a voltmeter with a range of 0

− 20 V

between the alternator "B" terminal and the earth
[Connect the (+) lead of the voltmeter to the "B"
terminal, and then connect the (-) lead of the
voltmeter to the earth].

6. Connect the negative battery cable.
7. Connect the M.U.T.-II/III.
8. Leave the hood open.
9. 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 "B" terminal and the battery (+) ter-
minal.

10.Turn the lamp switch on to turn on headlamps and

then start the engine.

11.Immediately after setting the headlamps to high

beam and turning the heater blower switch to the
high revolution position, increase the engine
speed to 2,500 r/min and read the maximum
current output value displayed on the ammeter.

Limit: 70% of normal current output

NOTE:

•

For the nominal current output, refer to the
Alternator Specifications.

•

Because the current from the battery will soon
drop after the engine is started, the above step
should be carried out as quickly as possible in
order to obtain the maximum current output
value.

•

The current output value will depend on the
electrical load and the temperature of the
alternator body.

•

If the electrical load is small while testing, the
specified level of current may not be output
even though the alternator is normal. In such
cases, increase the electrical load by leaving
the headlamps turned on for some time to dis-
charge the battery or by using the lighting sys-
tem in another vehicle, and then test again.

•

The specified level of current also may not be
output if the temperature of the alternator body
or the ambient temperature is too high. In such
cases, cool the alternator and then test again.

12.The reading on the ammeter should be above the

limit value. If the reading is below the limit value
and the alternator output wire is normal, remove
the alternator from the engine and check the
alternator.

13.Run the engine at idle after the test.
14.Turn the ignition switch to the "LOCK" (OFF)

position.

15.Remove the M.U.T.-II/III.
16.Disconnect the negative battery cable.
17.Disconnect the ammeter and voltmeter.
18.Connect the negative battery cable.

CHARGING SYSTEM

ENGINE ELECTRICAL

16-8

REGULATED VOLTAGE TEST

M1161001100871

AK401827 AC

Battery

Ignition switch

Engine-ECU

Ammeter (clamp-type)

Load

Blue

MB991519

Voltmeter (digital-type)

Red

Yellow

Black

Alternator

Charge warning lamp

–

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

• Check that the battery installed in the vehicle is

fully charged.

(Refer to GROUP 54A

− Battery − On-vehicle Serv-

ice

− Charging

P.54A-4

• Drive belt tension

(Refer to GROUP 11A

− On-vehicle Service

P.11A-7

• Fusible link

• Abnormal noise from the alternator while 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. Connect a clamp-type DC test ammeter with a

range of 0

− 100 A to the alternator "B" terminal

6. Reconnect the negative battery cable.
7. Connect the M.U.T.-II/III.
8. 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 (+) ter-
minal.

9. Turn all lamps and accessories off.
10.Start the engine.
11.Increase the engine speed to 2,500 r/min.
12.Read the value displayed on the voltmeter when

the alternator output current alternator becomes
10 A or less.

Content .. 345 346 347 348 ..