2005 MITSUBISHI 380 Workshop Manual

HOW TO DIAGNOSE
GENERAL 00E-4
INSPECTIONM1001004600139
1. Sight and sound checks
Check relay operation, blower motor rotation, light
illumination, etc. Listen for a "click" when some relay covers
are pushed down.
2. Simple checks
For example, if a headlight does not come on and a faulty
fuse or poor grounding is suspected, replace the fuse with a
new one. Or use a jumper wire to ground the light to the
body. Determine which part(s) is/are responsible for the
problem.
3. Checking with instruments
Use an appropriate instrument in an adequate range and
read the indication correctly.

HOW TO DIAGNOSE
GENERAL 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 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 00E-7
CHECKING SWITCHESM1001004800144
In a circuit diagram, a switch is shown in the idle state.
1. Normally open or normally closed switch
Switches are classified into those which open the circuit and
those which close the circuit when off.
Switches are shown in their normal state unless specified
otherwise.
2. Switch connection
This figure illustrates a complex switch. The continuity
between terminals at each position is as indicated in the
table below.
SWITCH
POSITIONTESTER
CONNECTIONSPECIFIED
CONNECTION
OFF
1st stage 156 Continuity
2nd stage 1
46 Continuity
3rd stage 1
36 Continuity
4th stage 1
26 Continuity

HOW TO DIAGNOSE
GENERAL 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 00E-9
CABLES AND WIRES CHECKM1001005100041
1. Check connections for looseness, rust, and stains.
2. Check terminals and wires for corrosion.
3. Check terminals and wires for open circuit or impending
open circuit.
4. Check wire insulation and coating for damage, cracks, and
wear.
5. Check conductive parts of terminals for contact with other
metallic parts (vehicle body and other parts).
6. Check grounding parts to verify that there is complete
continuity between attaching bolt(s) and vehicle body.
7. Check for incorrect wiring.
8. Check that harnesses are secured to prevent contact with
sharp edges and corners or hot parts (exhaust manifold,
pipe, etc.).
9. Check that harnesses are secured firmly to provide enough
clearance from the fan pulley, fan belt, and other rotating or
moving parts.
10.Check that the harnesses between fixed parts (such as the
vehicle body) and vibrating parts (such as the engine) are
long enough to allow for vibration and movement.
BATTERY HANDLINGM1001005200048
Battery posts, terminals and related accessories con-
tain lead and lead compounds. WASH HANDS AFTER
HANDLING.
When checking or servicing does not require power from the
vehicle battery, be sure to disconnect the cable from the battery
(
) terminal. This will prevent problems that could be caused by
a short circuit. Disconnect the (
) battery terminal first and
reconnect it last.
GENERAL ELECTRICAL SYSTEM CHECKM1001005300045
A circuit consists of the power supply, switch, relay, load,
ground, etc. There are various methods to check a circuit
including an overall check, voltage check, short-circuit check,
and continuity check. Each of the methods briefly described
below applies only to circuits similar to the illustration.

HOW TO DIAGNOSE
GENERAL 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 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.