Mitsubishi 380. Manual - part 246

CHARGING SYSTEM

ENGINE ELECTRICAL

16-6

SPECIAL TOOL

M1161000600486

TOOL

TOOL NUMBER AND 
NAME

SUPERSESSION

APPLICATION

Diagnostic tool (MUT-III)

A: MB991824

Vehicle 
communication 
interface (V.C.I.)

B: MB991827

MUT-III USB cable

C: MB991910

MUT-III main harness 
A (Vehicles with CAN 
communication 
system)

D: MB991911

MUT-III main harness 
B (Vehicles without 
CAN communication 
system)

E: MB991914

MUT-III main harness 
C (for Daimler Chrysler 
models only)

F: MB991825

MUT-III measurement 
adapter

G: MB991826

MUT-III trigger 
harness

MB991824-KIT

NOTE: G: MB991826 
MUT-III Trigger Harness 
is not necessary when 
pushing V.C.I. ENTER 
key.

Checking of engine 
speed

CAUTION

For vehicles with CAN 
communication, use 
MUT-III main harness A 
to send simulated 
vehicle speed. If you 
connect MUT-III main 
harness B instead, the 
CAN communication 
does not function 
correctly.

MB998467
Alternator harness 
connector

MIT530
Micrd 530 charging 
system tester.

Checking of alternator 
("S" terminal voltage)

MB991910

MB991826

MB991958

MB991911

MB991914

MB991824

MB991827

MB991825

DO NOT USE

A

B

C

D

E

F

G

DO NOT USE

CHARGING SYSTEM

ENGINE ELECTRICAL

16-7

ON-VEHICLE SERVICE

ALTERNATOR OUTPUT WIRE VOLTAGE DROP TEST

M1161000900669

Required Special Tool:
: Diagnostic Tool (MUT-III)

• MB991824: V.C.I.

• MB991827: MUT-III USB Cable

• MB991910: MUT-III Main Harness A

This test determines whether the wiring from the 
alternator "B" terminal to the positive battery terminal 
(including the fusible link) is in good condition or not:

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.

• Alternator installation
• Alternator drive belt tension (Refer to GROUP 00, 

General 

− Maintenance Service − Drive Belts 

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

P.00-39

.)

• 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 positive battery 
terminal. (Connect the positive lead of the 
voltmeter to the "B" terminal, and then connect the 
negative lead of the voltmeter to the positive 
battery cable.)

6. Reconnect the negative battery cable.

7. Connect an engine tachometer or diagnostic tool.

8. Leave the hood open.

9. Start the engine.

06DB027A

ALTERNATOR

AMMETER

(CLAMP-TYPE)

VOLTMETER

(DIGITAL-TYPE)

"B" TERMINAL

BATTERY

CHARGING SYSTEM

ENGINE ELECTRICAL

16-8

10.With the engine running at 2,500 r/min, turn the 

headlights and other lights on and off to adjust the 
alternator load so that the value displayed on the 
ammeter is slightly above 30 A.

Read the voltmeter. Voltage reading at or below 
limit value means voltage drop between alternator 
and battery is OK.

Limit value: maximum 0.3 V 

NOTE: When the alternator output is high and the 
value displayed on the ammeter does not 
decrease to 30 A, set the value to 40 A. Read the 
value displayed on the voltmeter at this time.
In this case the limit value becomes maximum 0.4 
V.
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.

11.If the value displayed on the voltmeter is above 

the limit value, there is probably a malfunction in 
the alternator output wire. Check the wiring 
between the alternator "B" terminal and the 
positive battery terminal (including fusible link).

If a terminal is not sufficiently tight or if the 
harness has become discolored due to 
overheating, repair and then test again.

12.After the test, run the engine at idle. 

13.Turn off all lights and turn the ignition switch to the 

"LOCK" (OFF) position.

14.Disconnect the engine tachometer or diagnostic 

tool.

15.Disconnect the negative battery cable.

16.Disconnect the ammeter and voltmeter.

17.Connect the negative battery cable.

18.Run the engine for 10 minutes at an idle.

OUTPUT CURRENT TEST

M1161001000670

06DB026A

ALTERNATOR

AMMETER

(CLAMP-TYPE)

VOLTMETER

IGNITION

SWITCH

LOAD

B

L

S

ALTERNATOR

MALFUNCTION

LIGHT

COMBINATION METER

BATTERY

+

–

CHARGING SYSTEM

ENGINE ELECTRICAL

16-9

Required Special Tool:
: Diagnostic Tool (MUT-III)

• MB991824: V.C.I.

• MB991827: MUT-III USB Cable

• MB991910: MUT-III Main Harness A

This test determines whether the alternator 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.

• Alternator installation

• Battery (Refer to GROUP 54A, Chassis Electrical 

− Battery − On-vehicle Service − Battery Check 

P.54A-5

.)

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.

• Alternator drive belt tension (Refer to GROUP 00, 

General 

− Maintenance Service − Drive Belts 

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

P.00-39

.)

• 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.

WARNING

Never use clips to connect the wire. Loose 
connections (for example, 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 

− 120 A to the alternator "B" terminal 

output wire. 

5. Connect a voltmeter with a range of 0 

− 20 V 

between the alternator "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 diagnostic tool.

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 alternator "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 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 
Alternator Specifications.

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

NOTE: 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 
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 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 speed after the test.

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

position.

15.Disconnect the engine tachometer or diagnostic 

tool.

16.Disconnect the negative battery cable.

17.Disconnect the ammeter and voltmeter .

18.Connect the negative battery cable.

19.Run the engine for 10 minutes at an idle.