Mitsubishi Evolution X. Manual — part 239

CHARGING SYSTEM

TSB Revision

ENGINE ELECTRICAL

16-9

• MB991910: M.U.T.-III Main Harness A

This test determines whether the generator outputs
normal current. For best results, use a charging sys-
tem tester. If not available, follow the steps below.

WARNING

Battery posts, terminals and related acces-
sories contain lead and lead compounds.
WASH HANDS AFTER HANDLING.

1. Before the test, always be sure to check the

following.

• Generator installation

• Battery (Refer to GROUP 54A, Chassis Electrical

− Battery − On-vehicle Service − Battery Test

P.54A-9

.)

NOTE: The battery to be used should be slightly
discharged. The load in a fully-charged battery
will be insufficient and the test may not be able to
be carried out correctly.

• Generator drive belt tension (Refer to GROUP

00, General

− Maintenance Service − Drive Belts

(For Generator, Power Steering Pump and Air
Conditioning) (Check)

P.00-66

.)

• Fusible link

• Abnormal noise from the generator while the

engine is running.

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

position.

3. Disconnect the negative battery cable.
4. Set a clamp-type DC test ammeter to the

generator "B" terminal output wire.
NOTE: Disconnecting the generator output wire
and connecting the ammeter may not thoroughly
diagnosis an output current drop problem
because of an insufficient connection between
terminal "B" and the output wire.

5. Connect a voltmeter with a range of 0

− 20 V

between the generator "B" terminal and ground.
(Connect the positive lead of the voltmeter to the
"B" terminal, and then connect the negative lead
of the voltmeter to ground.)

6. Connect the negative battery cable.
7. Connect an engine tachometer or scan tool

MB991958.

8. Leave the hood open.
9. Check to be sure that the reading on the voltmeter

is equal to the battery positive voltage.

NOTE: If the voltage is 0 V, the cause is probably
an open circuit in the wire or fusible link between
the generator "B" terminal and the battery positive
terminal or malfunctioning voltmeter.

10.After turning on the headlights, start the engine.

NOTE: Because the current from the battery will
soon drop after the engine is started, step 11
should be carried out as quickly as possible in
order to obtain the maximum current output value.

11.Immediately after setting the headlights to high

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

Limit value: 70 % of nominal current output

NOTE: For the nominal current output, refer to the
Generator Specifications.
NOTE: The current output value will depend on
the electrical load and the temperature of the gen-
erator body.
NOTE: If the electrical load is small while testing,
the specified level of current may not be output
even though the generator is normal. In such
cases, increase the electrical load by leaving the
headlights turned on for some time to discharge
the battery or by using the lighting system in
another vehicle, and then test again.
NOTE: The specified level of current also may not
be output if the temperature of the generator body
or the ambient temperature is too high. In such
cases, cool the generator 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 generator output wire is normal, remove
the generator from the engine and check the
generator.

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

position.

15.Disconnect the engine tachometer or scan tool

MB991958.

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

CHARGING SYSTEM

TSB Revision

ENGINE ELECTRICAL

16-10

REGULATED VOLTAGE TEST

M1161001101625

AK503329 AB

Battery

CAN communication

ECM

Ammeter (clamp-type)

Load

Blue

MB991519

Voltmeter (digital-type)

Yellow

Red

Black

Generator

B

FR

L

S

G

Generator
malfunction light

Combination meter

+

-

+

-

Required Special Tools:

• MB991958: Scan Tool (M.U.T.-III Sub Assembly)

• MB991824: V.C.I.

• MB991827: M.U.T.-III USB Cable

• MB991910: M.U.T.-III Main Harness A

• MB991519: Generator Harness Connector

This test determines whether the voltage regulator is
correctly controlling the generator output voltage.

WARNING

Battery posts, terminals and related acces-
sories contain lead and lead compounds.
WASH HANDS AFTER HANDLING.

1. Always be sure to check the following before the

test:

• Generator installation

• Check to be sure that the battery installed in the

vehicle is fully charged. (Refer to GROUP 54A,
Chassis Electrical

− Battery − On-vehicle Service −

Battery Test

P.54A-9

.)

• Generator drive belt tension (Refer to GROUP

00, General

− Maintenance Service − Drive Belts

(For Generator, and Air Conditioning) (Check)

P.00-66

.)

• Fusible link

• Abnormal noise from the generator 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 (Generator harness

connector: MB991519) to connect a digital-type
voltmeter between the generator "S" terminal and
ground. (Connect the positive lead of the
voltmeter to the "S" terminal, and then connect the
negative lead of the voltmeter to a secure ground
or to the negative battery terminal.)

5. Set a clamp-type DC test ammeter to the

generator "B" terminal output wire.

6. Reconnect the negative battery cable.
7. Connect an engine tachometer, or scan tool

MB991958.

8. Turn the ignition switch to the "ON" position and

check that the reading on the voltmeter is equal to
the battery positive voltage.
NOTE: If the voltage is 0 V, the cause is probably
an open circuit in the wire or fusible link between
the generator "S" terminal and the battery positive
terminal or malfunctioning voltmeter.

CHARGING SYSTEM

TSB Revision

ENGINE ELECTRICAL

16-11

9. Check to be sure that all lights and accessories

are 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 current output by the generator becomes 15 A
or less.

13.If the voltage reading conforms to the value in the

voltage regulation table, then the voltage regulator
is operating normally.
If the voltage is outside the standard value, there
is a malfunction of the voltage regulator or the
generator (Refer to the following table).

NOTE: When the voltage is approximately 12.8 V,
the G-terminal is supposed to have a short circuit
to the earth. Check the circuits relating to the
G-terminal on the generator. (Refer to GROUP
13A

−

Troubleshooting

−

Inspection chart for trou-

ble symptoms)

14.After the test, lower the engine speed to idle.
15.Turn the ignition switch to the "LOCK" (OFF)

position.

16.Disconnect the engine tachometer or scan tool

MB991958.

17.Disconnect the negative battery cable.
18.Disconnect the ammeter and voltmeter.
19.Remove the special tool (Generator harness

connector: MB991519), and return the connector
to the original condition.

20.Connect the negative battery cable.

VOLTAGE REGULATION TABLE

INSPECTION TERMINAL

VOLTAGE REGULATOR AMBIENT
TEMPERATURE [

° C (° F)]

STANDARD VALUE (V)

Terminal "S"

−20 (−4)

14.2

− 15.4

20 (68)

13.9

− 14.9

60 (140)

13.4

− 14.6

80 (176)

13.1

− 14.5

WAVE PATTERN CHECK USING AN
OSCILLOSCOPE

M1161001200663

.

MEASUREMENT METHOD

AK604150

Generator

CH1

AB

"B" terminal

Connect the oscilloscope special patterns pick-up to the gener-
ator "B" terminal.

.

CHARGING SYSTEM

TSB Revision

ENGINE ELECTRICAL

16-12

STANDARD WAVEFORM

Observation Conditions

FUNCTION

SPECIAL PATTERNS

Pattern height

Variable

Variable knob

Adjust while viewing the
wave pattern

Pattern selector

Raster

Engine revolutions

Curb idle speed

AK604151

0.4

(V)

0.2

0

–0.2

–0.4

Voltage at
generator
"B" terminal

Time

AB

AKX00190

NOTE: The voltage waveform of the generator "B" terminal can
undulate as shown at left. This waveform is produced when the
regulator operates according to fluctuations in the generator
load (current), and is normal for the generator.
If the ripple height is abnormally high (approximately 2 V or
more during idling), the wires between the generator "B" termi-
nal and the battery have broken due to fuse blowing, etc. The
generator is usually operating properly.

.