Mitsubishi Pajero Pinin. Manual - part 143

 

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Mitsubishi Pajero Pinin. Manual - part 143

 

 

ENGINE ELECTRICAL – 

Charging System

16-2

CHARGING SYSTEM

GENERAL INFORMATION

The charging system uses the alternator output to
keep the battery charged at a constant level under
various electrical loads.

OPERATION

Rotation of the excited field coil generates AC voltage in the
stator.
This alternating current is rectified through diodes to DC voltage
having a waveform shown in the illustration at left. The average
output voltage fluctuates slightly with the alternator load
condition.

When the ignition switch is turned on, current flows
in the field coil and initial excitation of the field coil
occurs.
When the stator coil begins to generate power after
the engine is started, the field coil is excited by
the output current of the stator coil.
The alternator output voltage rises as the field
current increases and it falls as the field current
decreases. When the battery voltage (alternator S
terminal voltage) reaches a regulated voltage of

approx. 14.4 V, the field current is cut off. When
the battery voltage drops below the regulated
voltage, the voltage regulator regulates the output
voltage to a constant level by controlling the field
current.
In addition, when the field current is constant, the
alternator output voltage rises as the engine speed
increases.

SYSTEM DIAGRAM

Stator coil

Field coil

Voltage
regulator

Engine-ECU

Charging
warning lamp

Ignition
switch

Battery

B

G

L
FR

S

+

–

Voltage

Time

Approx. 14.4 V

ENGINE ELECTRICAL – 

Charging System

16-3

ALTERNATOR SPECIFICATIONS

Items

Specifications

Type

Battery voltage sensing

Rated output V/A

12/100

Voltage regulator

Electronic built-in type

SERVICE SPECIFICATIONS

Items

Standard value

Limit

Alternator output line voltage drop (at 30 A) V

–

Max. 0.3

Regulated voltage ambient
temp at voltage regulator V

– 20

_

C

14.2 – 15.4

–

temp. at voltage regulator V

20

_

C

13.9 –14.9

–

60

_

C

13.4 – 14.6

–

80

_

C

13.1 – 14.5

–

Output current

–

70% of normal output current

SPECIAL TOOL

Tool

Number

Name

Use

MB991519

Alternator test
harness

Checking the alternator (S terminal voltage)

ENGINE ELECTRICAL – 

Charging System

16-4

ON-VEHICLE SERVICE

ALTERNATOR OUTPUT LINE VOLTAGE DROP TEST

Alternator

Terminal B

Voltmeter

Ammeter

Battery

+

–

+

–

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

the test.

D

Alternator installation

D

Alternator drive belt tension

D

Fusible link

D

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) Disconnect the alternator output wire from the

alternator “B” terminal and 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, and then connect
the (–) lead of the ammeter to the disconnected
output wire.)

NOTE
An inductive-type ammeter which enables
measurements to be taken without disconnect-
ing the alternator output wire should be
recommended. Using this equipment will lessen
the possibility of a voltage drop caused by a
loose “B” terminal connection.

(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 the connect the (–) lead
of the voltmeter to the battery (+) cable.)

ENGINE ELECTRICAL – 

Charging System

ENGINE ELECTRICAL – 

Charging System

16-5

(6) Reconnect the negative battery cable.
(7) Connect a tachometer or the MUT-

II

.

(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: max. 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 max.
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 discolored due to
overheating, repair and then test again.

(12)After the test, run the engine at idle.
(13)Turn off all lamps and the ignition switch.
(14)Remove the tachometer or the MUT-

II

.

(15)Disconnect the negative battery cable.
(16)Disconnect the ammeter and voltmeter.
(17)Connect the alternator output wire to the

alternator “B” terminal.

(18)Connect the negative battery cable.

OUTPUT CURRENT TEST

Charging warning lamp

Voltmeter

Ammeter

Ignition switch

Alternator relay

Load

Battery

Engine
-ECU

Alternator

FR

L

S

G

+

–

+

–

B

 

 

 

 

 

 

 

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