light MITSUBISHI 380 2005 Repair Manual

HOW TO DIAGNOSE
GENERAL <ELECTRICAL>00E-5
INSPECTION INSTRUMENTSM1001004700040
For inspection, use the following instruments:
Never use a test light for checking ECU-related circuits or
ECUs.
1. Test light
A test light consists of a 12V bulb and lead wires. It is used
to check voltages or short circuits.
2. Self-powered test light
A self-powered test light consists of a bulb, battery and lead
wires connected in series. It is used to check continuity or
grounding.
Never use a jumper wire to connect a power supply
directly to a load.
3. Jumper wire
A jumper wire is used to close an open circuit.
4. Voltmeter
A voltmeter is used to measure the circuit voltage. Normally,
the positive (red lead) test probe is applied to the point of
voltage measurement and the negative (black lead) test
probe to the body ground. Use a digital voltmeter to check
for voltage drop before or after a component.

HOW TO DIAGNOSE
GENERAL <ELECTRICAL>00E-6
5. Ohmmeter
An ohmmeter is used to check continuity or measure
resistance of a switch or coil. If the measuring range has
been changed, the zero point must be adjusted before
measurement.
CHECKING FUSESM1001005000044
A blade type fuse has test taps provided to allow checking of
the fuse itself without removing it from the fuse block. The fuse
is okay if the test light comes on when its one lead is connected
to the test taps (one at a time) and the other lead is grounded.
Remember to turn the ignition switch to ON to ensure all cir-
cuits are live.
CAUTIONS IN EVENT OF BLOWN FUSE
When a fuse is blown, there are two probable causes. One is
that it is blown due to flow of current exceeding its rating. The
other is that it is blown due to repeated on/off current flowing
through it. Which of the two causes is responsible can be easily
determined by visual check as described below.
1. Fuse blown due to current exceeding rating
The illustration shows the state of a fuse blown due to this
cause. In this case, do not replace the fuse with a new one
hastily since a current heavy enough to blow the fuse has
flowed through it. First, check the circuit for shorts and check
for abnormal electric parts. After correcting shorts or
replacing parts, use only a fuse of the same capacity as a
replacement. Never use a fuse of larger capacity than the
original fuse. If a larger capacity fuse is used, electric parts
or wiring could be damaged, or could start a fire.
2. Fuse blown due to repeated turning current on and off
The illustration shows the state of a fuse blown due to
repeated current on/off. Normally, this type of problem
occurs after a fairly long period of use and is less frequent
than above. In this case, simply replace with a new fuse of
the same capacity.

HOW TO DIAGNOSE
GENERAL <ELECTRICAL>00E-8
CHECKING RELAYSM1001004900152
1. By using a relay, a heavy current can be turned on and off by
a switch using much less current. For example, in the circuit
shown here, when the switch is turned on (closed), current
flows to the coil of the relay. Then, its contact is turned on
(closed) and the light comes on. The current flowing through
the switch is much less than that for the light.
2. When current flows through the coil of a relay, its core is
magnetized to attract the iron piece, closing (ON) the
contact at the tip of the iron piece. When the coil current is
turned off, the iron piece returns to its original position by a
spring, opening the contact (OFF).
3. Relays may be classified as the normally open-type or the
normally closed-type, depending on their contact
construction.
NOTE: The deenergised state means that no current is flow-
ing through the coil. The energised state means that current
is flowing through the coil.
(1) The normally open-type
When a normally open relay as illustrated here is
checked, there should be no continuity between terminals
3 and 4 when the relay is deenergised. There should be
continuity between terminals 3 and 4 when battery
voltage and ground are applied to terminals 1 and 2. The
relay condition is determined by this check.
NOTE: Check the relay in both situation which is
energised and is not energised.
(2) The normally closed-type
When a normally closed relay as illustrated here is
checked, there should be continuity between terminals 3
and 4 when the relay is deenergised. There should be no
continuity between terminals 3 and 4 when battery
voltage and ground are applied to terminals 1 and 2. The
relay condition is determined by this check.
NOTE: Check the relay in both situation which is
energised and is not energised.

HOW TO DIAGNOSE
GENERAL <ELECTRICAL>00E-10
1. VOLTAGE CHECK
(1) Ground one lead wire of the test light. If a voltmeter is
used instead of the test light, ground the grounding side
lead wire.
(2) Connect the other lead wire of the test light to the power
side terminal of the switch connector. The test light
should come on or the voltmeter should indicate a
voltage.
(3) Then, connect the test light or voltmeter to the motor
connector. The test light should not come on, or the
voltmeter should indicate no voltage. When the switch is
turned ON in this state, the test light should come on, or
the voltmeter should indicate a voltage, with the motor
starting to run.
(4) The circuit illustrated here is normal. If there is any
problem, such as the motor failing to run, check voltages
beginning at the connector nearest to the motor until the
faulty part is identified.
2. SHORT-CIRCUIT CHECK
Because the fuse has blown, it is probable that there is a
short circuit. Follow the procedures below to narrow down
the short-circuit location.
STEP 1. Remove the blown fuse and connect the test light
across the fuse terminals (Circuit switch: OFF).
Q: Does the test light illuminate?
YES : Short-circuit exists between the fuse block and the
switch. Diagnose the harness between the fuse block
and the switch.
NO : Go to Step 2.

HOW TO DIAGNOSE
GENERAL <ELECTRICAL>00E-11
STEP 2. Turn the switch ON and disconnect the
illumination light connector.
Q: Does the test light illuminate?
YES : Short-circuit exists between the switch and the
connector. Diagnose the harness between the switch
and the connector.
NO : Short-circuit exists between the connector and the
illumination light. Diagnose the harness between the
connector and the illumination light.

HOW TO DIAGNOSE
GENERAL <ELECTRICAL>00E-12
3. CONTINUITY CHECK
(1) When the switch is in the &#34;OFF&#34; position and the contact
points of terminals 1 and 2 are connected, the
self-powered test light should illuminate or the ohmmeter
should read 0 ohm.
(2) When the switch is the &#34;ON&#34; position and the contact
points of terminals 3 and 4 are connected, the
self-powered test light should come on or the ohmmeter
should read 0 ohm.

SPECIAL TOOLS
INTAKE AND EXHAUST15-3
INSPECTION PROCEDURE 2: Abnormal Noise
DIAGNOSIS
STEP 1. Start the engine. Have an assistant stay
in the drivers seat. Raise the vehicle on a hoist.
Have the assistant rev the engine while
searching for exhaust leaks.
Q: Is any abnormal noise generated?
YES :
Go to Step 2.
NO : The procedure is complete.
STEP 2. Check for missing parts in the muffler.
Tap the muffler lightly to check for loose baffles,
etc.
Q: Are there any missing parts in the muffler?
YES :
Replace, then go to Step 1.
NO : Go to Step 3.
STEP 3. Check the hanger for cracks.
Q: Is the hanger cracked?
YES :
Replace, then go to Step 1.
NO : Go to Step 4.
STEP 4. Check for interference of the pipes and
muffler with the body.
Q: Are the pipes and muffler interfering with the
body?
YES :
Repair, then go to Step 1.
NO : Go to Step 5.
STEP 5. Check the heat protectors.
Q: Are any heat protectors loose or damaged?
YES :
Tighten or replace, then go to Step 1.
NO : Go to Step 6.
STEP 6. Check the pipes and muffler for damage.
Q: Are the pipes and muffler damaged?
YES :
Replace, then go to Step 1.
NO : There is no action to be taken.
SPECIAL TOOLSM1151000600429
TOOL TOOL NUMBER AND
NAMESUPERSESSION APPLICATION
MD998412
GuideMD998412 Installation of intake
manifold plenum
MB991953
Oxygen sensor wrench- Removal and installation
of heated oxygen sensor
MD998770
Oxygen sensor wrenchMD998770-01 or General
service toolRemoval and installation
of heated oxygen sensor

16-2
CHARGING SYSTEM
GENERAL DESCRIPTIONM1161000100629
The charging system charges the battery with the
alternator output to keep the battery charged at a
constant level during varying electrical load.
OPERATION
Rotation of the excited field coil generates AC volt-
age in the stator.
This alternating current is rectified through diodes to
DC voltage having a waveform shown in the illustra-
tion above.
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 cur-
rent increases and it falls as the field current
decreases. When the battery positive voltage
(alternator S terminal voltage) reaches a regulated
voltage of approximately 14.4 V, the field current is
cut off. When the battery positive 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.

CHARGING SYSTEM
ENGINE ELECTRICAL16-3
CHARGING SYSTEM DIAGNOSISM1161000700427
TROUBLESHOOTING HINTS
Alternator malfunction light dose not go on when the ignition
switch is turned to ON, before the engine starts.
Check the bulb.
Alternator malfunction light dose not switch off after the engine
starts.
Check the IC voltage regulator inside the
alternatoralternator.
Discharged or overcharged battery.
Check the IC voltage regulator inside the alternator.
The alternator malfunction light illuminates dimly.
Check the diode (inside the combination meter) for a
short-circuit.
TROUBLESHOOTING GUIDE
The charging system troubleshooting guide is shown in the fol-
lowing steps.
STEP 1.
Q: Is the battery in good condition? (Refer to GROUP 54A,
Chassis Electrical
Battery On-vehicle Service
Battery Check P.54A-5.)
YES : Go to Step 2.
NO : Charge or replace the battery.
STEP 2.
Q: Is the alternator drive belt in good condition? (Refer to
GROUP 00, General
Maintenance Service Drive Belts
(For Alternator, Power Steering Pump and Air
Conditioning) (Check) P.00-39.)
YES : Go to Step 3.
NO : Adjust the belt tension or replace the belt.
STEP 3.
Q: Does the alternator malfunction light come on when the
ignition switch is turned on?
YES : Go to Step 4.
NO :
Check the ignition switch. (Refer to GROUP 54A,
Chassis Electrical
Ignition Switch Ignition
Switch
Inspection P.54A-44.)
Check for burnt-out alternator malfunction light.
Check the alternator. (Refer to Charging System
Alternator Assembly
Inspection P.16-17.)
Check the alternator malfunction light-related
circuits.

CHARGING SYSTEM
ENGINE ELECTRICAL16-4
STEP 4.
Q: Does the alternator malfunction light go out after
starting the engine?
YES : Go to Step 5.
NO : Check the alternator (Refer to Charging System

Alternator Assembly
Inspection P.16-17.)
STEP 5.
Q: Is an oscilloscope available?
YES : Go to Step 6.
NO : Go to Step 7.
STEP 6.
Q: Does the oscilloscope show a normal wave pattern?
(Refer to Charging System
On-vehicle Service Wave
Pattern Check Using an Oscilloscope P.16-11.)
YES : Go to Step 7.
NO : Check the alternator. (Refer to Charging System

Alternator Assembly
Inspection P.16-17.)
STEP 7.
Engine: 2,500 r/min
Headlight: ON (high beam)
Voltage between alternator terminal B and the positive bat-
tery terminal
OK: 0.5 V or less
Voltage between the negative battery terminal and
alternator body
OK: 0.5 V or less
Q: Are the alternator output wire and ground wire in good
condition?
YES : Go to Step 8.
NO : Check the alternator output wire and ground wire.
STEP 8.
Q: Is the output current normal? (Refer to Charging
System
On-vehicle Service Output Current Test
P.16-8.)
YES : Go to Step 9.
NO : Check the alternator (Refer to Charging System

Alternator Assembly
Inspection P.16-17.)