1987 MITSUBISHI MONTERO engine

WIRING HARNESS - Troubleshooting
1660236
Power
supply
h
Fuse
ON
/----
/
/
Motor
1660239
CHECKING CABLES AND WIRES
1. Check connections for looseness, rust and stains.
2. Check terminals and wires for corrosion by battery electrolyte,
$tc.
3. Check terminals and wires for open circuit or impending open
circuit.
4. Check wire insulation and coating for damage, cracks and de-
grading.
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 conti-
nuity between attaching bolt(s) and vehicle body.
7. Check for incorrect wiring.
8. Check that wirings are so clamped as to ‘prevent contact with
sharp corners of the vehicle body, etc. or hot parts (exhaust
manifold, pipe, etc.).
9. Check that wirings are clamped firmly to secure enough clear-
ance from the fan pulley, fan belt and other rotating or moving
parts.
10. Check that the wirings between the fixed parts such as the
vehicle body and the vibrating parts such as the engine are
made with adequate allowance for vibrations.
HANDLING ON-VEHICLE BAlTERY
When checking or servicing does not require power from the on-
vehicle battery, be sure to disconnect the cable from the battery
(-)terminal. This is to prevent problems that could be caused by
shorting of the circuit. Disconnect the (-) terminal first and recon-
nect it last.
TROUBLESHOOTING
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, shortcircuit check and continuity
check. Each of these methods is briefly described in the following.
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 connector 0. The test light
should come on or the voltmeter should indicate a
voltage.
(3) Then, connect the test light or voltmeter to the
connector (3,. 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 but if there is any
problem such as the motor failing to run, check
voltages beginning at the connector nearest to the
motor unit the faulty part is identified. 1 ST6 Revision

8-20 WIRING HARNESS - How to Read Wiring Diagrams
HOW TO READ WIRING DIAGRAM NOEDBAE
HOW TO READ CONFIGURATION DIAGRAMS
(1) Connector symbols
A wiring diagram shows the installed condition of each connector in a schematic style. The connectors are
shown and classified as follows, depending on their locations and are marked by connector symbols.
In case connectors of the same shape (same number of wires) are centralized, their colors are indicated for
identification.
Examp’e : p.!- f.~~~~ ~;~~o,
Connector’s unique number (serial number)
A : Engine compartment
B : Interior and frame
C : Instrument panel
Main fusible link
A-03
A-o4
> 4WD indicator switch
A-05 Automatic transmission oil
I temperature switch indicates that the connector is located in the
Same connector No. is used in the wiring diagram and the circuit diagram.
I Indicates color of the
A-58 connector. I
1 ST6 Revision

8-28 WIRING HARNESS - Engine Compartment
1 ENGINE COMPARTMENT
Connector symbol
A
;:::I Main fusible link
;:::I 4WD indicator switch
A-05 Automatic transmission oil
temperature switch
A-06 Back-u light and 4WD indicator
A-07)wiring f!arness and cord
assembly combination
;:g> Back-up light switch
A-l 0 OD-OFF solenoid
A-l 1 Pulse generator
A-l 2 Front wiring harness and
transmission wiring harness
combination
A-13 Air conditioner solenoid valve
A-l 4 Front wiper motor A-
A156
A-55
A-l 7 Checker
A-18 Diode
A-19 Brake fluid level sensor
A-20 Front harness and back-up light
A-21 land 4WD indicator wiring
harness combination
it;;> Sub fusible link
A-24 Carburetor assembly
A-25 Control wiring harness and air
conditioner wiring harness
combination
A-26 Front wiring harness and control
wiring harness combination
A-27 Device box A-53 A-52
A-54
A-28 Auto choke relay
A-29 Front wiring harness and air
conditioner wiring harness
combination
A-30 Headlight washer motor
A-31 Front combination light (L.H.)
A-32 Light control relay
A-33 Dedicated fuse (Upper beam
indicator circuit)
A-34 Headlight (L.H.)
A-35 Condenser fan motor
A-40 Condenser fan motor relay
1 STB Revision

WIRING- HARNESS - Engine Compartment 8-29
; A-06 A-08 A-1 0 A-12 A-14
,.
1 A-15 8
I I
,I I I, I /
A-48
WI
&-ii& ’
A-35 Ai34 A!33 J-3:
A-39 A-37
36W618
A41
i-$ Ignition coil
A-44
A-45 Magnetic clutch
A-46 Water temperature sensor (FBC circuit)
;rii}Alternator
A-49 Water temperature switch (Air conditioner circuit)
A-50 Water temperature gauge unit
A-51 Water temperature switch (OD control circuit)
A-52 Oil pressure gauge or oil pressure switch
$3 Low pressure switch A-55 Headlight (R.H.)
A-56 Front harness and air conditioner wiring harness
combination
A-57 Front combination light (R.H.)
A-58 Front washer motor
A-59 Oxygen sensor
Remarks
(1) The mark * shows the reference mounting position of
wiring harness.
(2) For information concerning the ground points (exam-
ple:
q ), refer to P.8-7.
1 STB Revision

8-40 WIRING HARNESS - Layout of Components WC)
LAYOUT OFCOMPONENJS [FBC)
CD
II A
5FU131
Items
Symbol Items Symbol
Auto choke relay J Slow-cut solenoid valve D
Engine speed sensor (Ignition coil 0)
Feed back carburetor control unit G
Throttle opener control solenoid valve (for the
A
K air-conditioner)
Feed back solenoid valve
I
C Throttle position sensor
I E
Oxygen sensor
I H Vacuum switch
I F
Secondary air control solenoid valve
I I 1 Water temperature sensor
I B
Throttle opener contr
solenoid valve

CHARGING SYSTEM -Troubleshooting 8-75
TROUBLESHOOTING
NOBEH-
Symptom Probable cause
Remedy Reference
we
Charging warning in- Fuse blown
dicator does not light
with ignition switch Light burned out
“ON” and engine off. 1
1 Wiring connection loose Check fuses
Replace light
Tighten loose connections 8-70
-
-
Charging warning in-
dicator does not go
out with engine
running
(Battery requires fre-
quent recharging)
L
t
Run-down battery
c
Electronic voltage regulator faulty
Drive belt loose or worn
Battery cables loose, corroded or worn
Fuse blown
Fusible link blown
Electronic voltage regulator or alternator
faulty
Wiring faulty
Drive belt loose or worn
Wiring connection loose or open circuit
Fusible link blown Replace voltage regulator
Adjust tension or replace drive
belt
Repair or replace cables
Check fuses
Replace fusible link
Test alternator
Repair wiring
Adjust tension or replace drive
belt
Tighten loose connection or
repair wiring
Replace fusible link 8-79
Refer to
GROUPS.
8-8 1
8-70
8-69
8-77
8-79
-
Refer to
GROUP 9.
-
8-69
Poor grounding 1 Repair
I-
I I I Electronic voltage regulator or alternator
faulty Test alternator 8-77
8-79
Overcharge Decrease in life of battery
Replace battery
8-81 I
Electronic voltage regulator faulty Replace voltage regulator 8-79
STB Revision

CHARGING SYSTEM - Service Adjustment Procedures 8-77
SERVICE ADJUSTMENT PROCEDUREswmAB
lEL15I
INSPECTION OF THE CHARGING SYSTEM
VOLTAGE DROP TEST OF ALTERNATOR OUTPUT WIRE
This test judges whether or not the wiring (including the fusible
link) between the alternator B terminal and the battery (+) terminal
is sound by the voltage drop method.
Preparation
(1) Turn the ignition switch to “OFF”.
(2) Disconnect the battery ground cable.
(3) Disconnect the alternator output lead from the alternator “B”
terminal.
(4) Connect a DC ammeter (0 to 100 A) in series to the “B”
terminal and the disconnected output lead. Connect the (+)
lead of the ammeter to the “B” terminal and the (-) lead to
the disconnected output wire.
NOTE
Use of a clamp type ammeter that can measure current with-
out disconnecting the harness is preferred. The reason is that
when checking a vehicles that has a low output current due to
poor connection of the alternator “B” terminal, such poor con-
nection is corrected as the “B” terminal is loosened and a test
ammeter is connected in its place and as a result, causes for
the trouble may not be determined.
(5) Connect a digital voltmeter between the alternator “B” termi-
nal and battery (+) terminal. Connect the (+) lead wire of the
voltmeter to the “B” terminal and the (-) lead wire to the
battery (+) terminal.
(6) Connect the battery ground cable.
(7) Leave the hood open.
Test
(1) Start the engine.
(2) Turn on or off the headlights and small lights and adjust the
engine speed so that the ammeter reads 20 A and read off the
voltmeter indication under this condition.
Result
(1) It is okay if the voltmeter indicates the standard value. ’
Standard value : 0.2 V max.
(2) If the voltmeter indicates a value that is larger than the stan-
dard value, poor wiring is suspected, in which case check the
wiring from the alternator “B” terminal to fusible link to bat-
tery (+) terminal. Check for loose connection, color change
due to overheated harness, etc. and correct them before test-
ing again.
(3) Upon completion of the test, set the engine speed at idle. Turn
off the lights and turn off the ignition switch.
(4) Disconnect the battery ground cable.
(5) Disconnect the ammeter and voltmeter that have been con-
nected for the test purpose.
(6) Connect the alternator output wire to the alternator “B” ter-
minal.
(7) Connect the battery ground cable.
( STB Revision

8-78 CHARGING SYSTEM - Service Adiustment Procedures
80A
n
Relay with diode
Voltmeter
Ammeter Iad
176
OUTPUT CURRENT TEST
This test judges whether or not the alternator gives an output
current that is equivalent to the nominal output.
Preparation
(1) Prior to the test, check the following items and correct as
necessary.
(a) Check the battery installed in the vehicle to ensure that it
is in sound state*. The battery checking method is de-
scribed in “BATTERY”.
NOTE
*The battery that is used to test the output current should
be one that has been rather discharged. With a fully
charged battery, the test may not be conducted correctly
due to an insufficient load.
(b) Check tension of the alternator drive belt. The belt tension
check method is described in “GROUP 7 COOLING -
Service Adjustment Procedures”.
(2) Turn off the ignition switch.
(3) Disconnect the battery ground cable.
(4) Disconnect the alternator output wire from the alternator “B”
terminal.
(5) Connect a DC ammeter (0 to 100 A) in series between the “B”
terminal and the disconnected output wire. Connect the (+)
lead of the ammeter to the “B” terminal and connect the (-)
lead wire to the disconnected output wire.
NOTE
Tighten each connection by bolt and nut securely as a heavy
current will flow. Do not relay on clips.
(6) Connect a voltmeter (0 to 20 V) between the “B” terminal and
ground. Connect the (+) lead wire to the alternator “B” ter-
minal and (-) lead wire to a sound ground.
(7) Set the engine tachometer and connect the battery ground
cable.
(8) Leave the engine hood open.
Test
(1) Check to see that the voltmeter reads the same value as the
battery voltage.
If the voltmeter reads 0 V, an open circuit in the wire between
the alternator “B” terminal and battery (-) terminal, a blown
fusible link or poor grounding is suspected.
(2) Turn on the headlight switch and start the engine.
(3) Set the headlight at high beam and the heater blower switch
at HIGH, quickly increase the engine speed to 2500 rpm and
read the maximum output current value indicated by the am-
meter.
NOTE
After the engine start up, the charging current quickly drops.
therefore, above operation must be done quickly to read max-
imum current value correctly.
[ STB Revision
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