ECU MITSUBISHI MONTERO 2000 Service Manual Online

GDI -Troubleshooting 13A-98
Inspection procedure 25
Engine-ECU power supply and earth circuit system
Probable cause
The cause is probably a malfunction of the engine-ECU or one of the problems
listed at right.DOpen circuit or short-circuited harness wire in the
engine-ECU power supply circuit
DOpen circuit or short-circuited harness wire in the
engine-ECU earth circuit
DMalfunction of the engine-ECU
NG
RepairOK
Check the ignition switch. (Refer to
GROUP 54.)
(2), (3) NGCheck the harness wire between the
engine-ECU and engine controlrelay,
and repair if necessary.
(4) NG
Check the harness wire between the
engine-ECU and earth, and repair if nec-
essary.
(5) NG
NG
Repair
OK
Check the trouble symptoms.NGCheck the harness wire between the
engine-ECU and the battery, and repair
if necessary.
NG
Repair
NG
Replace the engine-ECU.
OK
Check the trouble symptoms.
OK
Check the following connectors:
D-117, D-118
Check the following connectors:
D-27, D-31 , E-13OK
Check the trouble symptoms.NGCheck the harness wire between the
engine-ECU and ignition switch, and re-
pair if necessary.
Measure at the engine-ECU connectors
D-117, D-118.
DDisconnect the connector, and
measure at the harness side.
(1) Voltage between 99 and earth
(Ignition switch: ON)
OK:
System voltage
(2) Voltage between 57 and earth
OK:
System voltage
(3) Voltage between 47, 59 and
earth (Ignition switch: ON)
OK:
System voltage (When ter-
minal 57 is shorted to
earth)
(4) Continuity between 46, 58 and
earth
OK:
Continuity
(5) Voltage between 60 and earth
OK:
System voltage(1) NGCheck the following connector:
D-208, D-223, E-13NG
Repair
Check the following connector:
D-14NG
Repair
Check the trouble symptoms.OK
NG


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GDI -Troubleshooting 13A-99
Inspection procedure 26
Engine control relay and ignition switch-IG system
Probable cause
When the ignition switch ON signal is input to the engine-ECU, the engine-ECU
turns on theengine controlrelay.
This causes system voltage to be supplied to the engine-ECU and to the
sensors and actuators.DMalfunction of the ignition switch
DMalfunction of the engine controlrelay
DOpen circuit or short-circuited harness wire of the
engine controlrelay circuit
DMalfunction of the engine-ECU
OK
Check the trouble symptoms.NGCheck the harness wire between the
battery and theengine controlrelay, and
repair if necessary.
OK
Check the engine-ECU power supply
and earth circuit system. (Refer to
P.13A-98, Inspection procedure 25.)
OK
Measure at the engine controlrelay con-
nector B-25X.
DDisconnect the connector, and
measure at the harness side.
DVoltage between 2, 3 and earth
OK:
System voltageNGCheck the following connector:
D-143NG
Repair
Check theengine controlrelay. (Refer
to P.13A-227.)NG
Replace
Inspection procedure 27
Ignition switch-ST system
Probable cause
The ignition switch-ST outputs a HIGH signal to the engine-ECU while the
engine iscranking.
The engine-ECU uses this signal to carry out functions such as fuel injection
control during starting.DMalfunction of the ignition switch
DOpen circuit or short-circuited harness wire of the
ignition switch circuit
DMalfunction of the engine-ECU
NG
RepairOK
Check the ignition switch. (Refer to
GROUP 54.)
NG
Replace the engine-ECU.
OK
Check the trouble symptoms.
OK
Check the following connector:
D-117NG
RepairOK
Check the trouble symptoms.NGCheck the harness wire between the
engine-ECU and the ignition switch.
Measure at the engine-ECU connector
D-117.
DDisconnect the connector, and
measure at the harness side.
DVoltage between 68 and earth
(Ignition switch: START)
OK:
8 V or moreNGCheck the following connectors:
C-01, E-113, E-114NG
Repair


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GDI -Troubleshooting 13A-100
Inspection procedure 28
Accelerator pedal position switch system
Probable cause
The accelerator pedal positionswitch detects that the acceleratorpedal isfully closed,
and sends a signal to the engine-ECU. The engine-ECU controlsidle speed,based
on this signal.DMaladjustment of the accelerator cable
DMaladjustment of the accelerator pedal positionswitch
DOpen circuit or short-circuited harness wire in the
accelerator pedal positionswitch system, or poor
connector contact
DMalfunction of the engine-ECU
NG
Repair
NG
Repair
Check the acceleratorpedal positionswitch. (Refer to P.13A-230.)NGReplace the accelerator pedal positionsensor assembly.
OK
Measure at accelerator pedal positionsensor connector D-135.
DDisconnect the connector, and measure at the harness side.
DVoltage between terminal 4 and earth
(Ignition switch: ON)
OK:
4 V or more
DContinuity between terminal 5 and earth
OK:
ContinuityNGCheck the following connector:
D-118
OK
Check trouble symptom.
NG
Check the harness wire between the engine-ECU and accelerator
pedal positionsensor.
OK
Check the following connector:
D-135NG
Repair
OK
Check trouble symptom.NGReplace the engine-ECU.
OK


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GDI -Troubleshooting 13A-101
Inspection procedure 29
Fuel pump (low pressure) system
Probable cause
The engine-ECU turns on the fuelpumprelay while theengine iscranking or running,
and supplies power source to the fuelpump(low pressure).DMalfunction of the fuel pumprelay
DMalfunction of the fuel pump(low pressure)
DOpen circuit or short-circuited harness wire in the fuel
pump(low pressure) circuit, or poor connector contact
DMalfunction of the engine-ECU
Check trouble symptom.NGCheck the harness wire between the
fuel pump(low pressure) and earth, and
repair if necessary.
NG
RepairOK
Check trouble symptom.NGCheck the harness wire between the
fuel pumprelay and engine-ECU, and
repair if necessary.
NG
RepairOK
NG
RepairOK
Check the ignition switch. (Refer to
GROUP 54 - Ignition Switch.)
(2) NGCheck the following connector:
F-11
MUT-
IIActuator test
07 Fuel pump(Refer to P.13A-110.)OK
Normal
NG
Check the fuelpumprelay. (Refer to
P.13A-227.)NG
Replace
OK
Measure at fuel pumprelay connector
B-27X.
DDisconnect the connector, and
measure at the harness side.
DVoltage between terminals 3, 4 and
earth
(Ignition switch: ON)
OK:
System voltageNGCheck the following connectors:
D-208, D-213, E-10NG
Repair
OK
Check trouble symptom.NGCheck the harness wire between the
fuel pumprelay and ignition switch.
OK
Measure at engine-ECU connector
D-116.
DDisconnect the connector, and
measure at the harness side.
DVoltage between terminal 21 and
earth (Ignition switch: ON)
OK:
System voltageNGCheck the following connector:
B-27X
OK
Measure at engine-ECU connector
D-116.
DDisconnect the connector, and
measure at the harness side.
DShort circuit between terminal 21
and earth (Ignition switch: ON)
OK:
The fuel pump operates(its
operation sound can be
heard).OKCheck the following connector:
D-116NG
Repair
OK
Check trouble symptom.NGReplace the engine-ECU.
NG
Measure at fuel pump(low pressure)
connector G-12.
DDisconnect the connector, and
measure at the harness side.
(1) Voltage between terminal 5 and
earth
(Ignition switch: ON)
OK:
System voltage
(2) Continuity between 4 and earth
OK:
Continuity(1) NGCheck the following connectors:
B-27X, D-124, E-13, F-11NG
Repair
OK
Check trouble symptom.NGCheck the harness wire between the
fuel pumprelay and fuelpump(low
pressure), and repair if necessary.
OK
Check the following connector:
G-12NG
Repair
OK
Check trouble symptom.
NG
Replace the fuel pump(low pressure).


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GDI -Troubleshooting 13A-102
Inspection procedure 30
Power steering fluid pressure switch system
Probable cause
The power steering fluid pressure switch sends a signal to the engine-ECU according
to power steering load.
Based on this signal, the engine-ECU controls the throttle control servo so thatidle
speed increases when the power steering is in operation.DMalfunction of the power steering fluid pressure switch
DOpen circuit or short-circuited harness wire in the power
steering fluid pressure switch circuit, or poor connector
contact
DMalfunction of the engine-ECU
NG
NG
RepairOK
Replace the engine-ECU.
NG
Repair
Check the power steering fluid pressure switch. (Refer to GROUP
37A - On-vehicle Service.)NG
Replace
OK
Measure at power steering fluid pressure switch connector B-51.
DDisconnect the connector, and measure at the harness side.
DVoltage between terminal 1 and earth
(Ignition switch: ON)
OK:
System voltageNGCheck the following connector:
D-117
OK
Check trouble symptom.
Check the harness wire between the engine-ECU and power steer-
ing fluid pressure switch.NG
RepairOK
OK
Check the following connector:
B-51
Check trouble symptom.NG
Inspection procedure 31
A/C switch and A/C relay system
Probable cause
If the engine-ECU receives a ‘A/C on’ signal, it operates the throttle control servo
and A/C compressor magnetic clutch so thatidlespeed increases.DMalfunction of the A/C control system
DMalfunction of the A/C switch
DOpen circuit or short-circuited harness wire in the A/C
switch circuit, or poor connector contact
DMalfunction of the engine-ECU
NG
NG
RepairOK
Check trouble symptom.
NG
Replace the engine-ECU.
Service the A/C compressor relay. (Refer to GROUP 55 - On-ve-
hicle Service.)NG
Replace
OK
Measure at engine-ECU connectors D-116, D-118.
DDisconnect the connector, and measure at the harness side.
DVoltage between terminals 20, 83 and earth
(Ignition switch: ON)
OK:
0-3V
(A/C switch: OFF)
System voltage
(A/C switch: ON)
DConnect terminal 20 to earth.
(Ignition switch: ON, A/C switch: ON)
OK:
A/C compressor clutch turns on.OKCheck the following connectors:
D-116, D-118
Check the A/C system. (Refer to GROUP 55 - On-vehicle Service.)


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GDI -Troubleshooting 13A-103
Inspection procedure 32
Stop lamp switch system
Probable cause
The engine-ECU determines whether the brakepedal is depressed or not, by means
of the stoplampswitch input signal.DMalfunction of the stoplampswitch
DOpen circuit or short-circuited harness wire in the stop
lampcircuit, or poor connector contact
DMalfunction of the engine-ECU
NG
NG
NG
Repair
Check the stoplampswitch. (Refer to GROUP 35 - Brake Pedal.)NG
Replace
OK
Measure at stoplampswitch connector D-136.
DDisconnect the connector, and measure at the harness side.
DVoltage between terminal 2 and earth
OK:
System voltageNG
OK
Check trouble symptom.
Check the harness wire between the battery and stoplampswitch.
NG
Repair
OK
Measure at engine-ECU connector D-117.
DDisconnect the connector, and measure at the harness side.
DVoltage between terminal 63 and earth
(Ignition switch: ON)
OK:
0 - 3 V (when the brakepedal is not depressed)
System voltage (when the brakepedal is depressed)NG
OK
Check trouble symptom.
Check the harness wire between the engine-ECU and stoplamp,
and repair if necessary.
OK
Check the following connector:
D-117NG
Repair
OK
Check trouble symptom.
NG
Replace the engine-ECU.
Check the following connectors:
D-26 , D-27, D-124

Check the following connectors:
D-26 , D-124 ,
D-128, E-13


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GDI -Troubleshooting 13A-104
Inspection procedure 33
Small lamp switch system
Probable cause
The engine-ECU determines whether the small lampswitch is on or off.
According to that information, the engine-ECU controls
alternator output current when the vehicle is started.DImproper connector contact,opencircuit or
short-circuited harness wire in thetaillampcircuit
DMalfunction of the engine-ECU
NG
Replace the engine-ECU.
OK
Check the trouble symptoms.
OK
Check the following connector:
D-118NG
Repair
Measure at the engine-ECU connector D-118.
DDisconnect the connector, and measure at the harness
side.
DVoltage between 88 and earth
(Lighting switch: ON)
OK:
System voltageNGCheck thetaillampcircuit. (Refer to ELECTRICAL WIRING.)
Inspection procedure 34
Injector driver system
Probable cause
The engine-ECU drives the injector by the drive signal.DMalfunction of the injector driver
DImproper connector contact,opencircuit or
short-circuited harness wire
DMalfunction of the engine-ECU
OK
Check the harness wire between the injector driver and engine-ECU.
NG
Replace the engine-ECU.
OK
Check the trouble symptoms.Transient malfunction
(Refer to GROUP 00 - Points to Note for Intermittent
Malfunctions.) OK
Use a analyzer to measure the signal waveform at the engine-ECU
connectors D-116 and D-118.
DEngine: idling
DVoltage between 96 and earth, and between 1 and earth
OK:
A normal waveform should be displayed as described
on P.13A-118 (INSPECTION PROCEDURE USING
AN ANALYZER).NGReplace the injector driver.
NGCheck the following connectors:
B-121, D-116Repair
NG
Repair
OK


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GDI -Troubleshooting 13A-110
ACTUATOR TEST REFERENCE TABLE
Item
No.Inspection
itemDrive contentsInspection contentsNormal conditionInspection
procedure
No.Reference
page
01InjectorsCut fuel to No. 1
injectorEngine:
After havingIdling condition
becomes differentCode No.
P020113A-38
02Cut fuel to No. 2
injector
warmed up/Engine
is idling
(Cut the fuel supply(becomes unsta-
ble).
Code No.
P020213A-40
03Cut fuel to No. 3
injectorto each injector in
turn and check
cylinders whichCode No.
P020313A-42
04Cut fuel to No. 4
injectordon’t affect idling.)Code No.
P020413A-44
05Cut fuel to No. 5
injectorCode No.
P020513A-46
06Cut fuel to No. 6
injectorCode No.
P020613A-48
07Fuel pump
(low pressure)Fuel pump
operates and
fuel is recirculated.Ignition switch: ONSound of opera-
tion is heard.Procedure
No. 2913A-101
08Purge
control
solenoid valveSolenoid valve
turns from OFF to
ON.Ignition switch: ONSound of opera-
tion can be heard
when solenoid
valve is
driven.Code No.
P044313A-62
17Basic ignition
timingSet the engine-
ECU to ignition
timing adjustment
modeIdling after engine
warm up5_BTDC--
21Condenser fanDrive the fan motorIgnition switch: ONThe fan motor
operatesProcedure
No.2113A-95
34Electronic-
controlled
throttle valve
systemStop the throttle
control servo.Ignition switch: ONThrottle valve is
opened slightly.Code No.
P122013A-64


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GDI -Troubleshooting 13A-114
Terminal
No.Normal condition Check requirements (engine condition) Check item
63Stop lamp switchDepress the brake pedal.System voltage
Release the brake pedal.0-3V
65A/C switch (2nd channel)Refer to GROUP 55 - Troubleshooting “Check at the A/C-ECU
terminal, engine-ECU output terminals.”
66Clutch switchDepress the clutch pedal.0-3V
Release the clutch pedal.System voltage
68Ignition switch-STEngine: Cranking8V or more
71Oxygen sensor (front)Engine: Warm up, and then hold the
engine speed at 2,500r/min (Use a
digital voltmeter).0«0.8 V alternates.
76Air flow sensor reset signalEngine: Idling0-1V
Engine: 3,000 r/min6-9V
78Throttle position sensor
(2nd channel)Ignition switch:
ONRelease the
accelerator pedal.4.5 - 5.5 V
Depress the
accelerator pedal
fully.0.4 - 0.6 V
79Accelerator pedal position
switchIgnition switch:
ONRelease the
accelerator pedal.0-1V
Depress the
accelerator pedal
fully.4V or more
80Vehicle speed sensorDIgnition switch: ON
DMove the vehicle forward.0«system voltage
alternates.
83A/C switch (1st channel)Engine: IdlingA/C switch: OFF0-3V
A/C switch: ON
(Compressor is
operating)System voltage
88Small lamp switchLighting switch: OFF0-3V
Lighting switch: ON (Taillamp: ON)System voltage
89Oxygen sensor heaterEngine: Idling0-3V
(front)
Engine: 3,500 r/minSystem voltage
90Oxygen sensor heaterEngine: Idling0-3V
(rear)
Engine: 3,500 r/minSystem voltage
92Fuel pressure sensorEngine: Idling0.3 - 4.7 V


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GDI -Troubleshooting 13A-115
Terminal
No.Normal condition Check requirements (engine condition) Check item
94Accelerator pedal position
sensor (1st channel)Ignition switch:
ONRelease the acceler-
ator pedal.0.3 - 1.0 V*1
Depress the
accelerator pedal
fully.4.2 - 5.5 V*2
96Injector open circuit check
signalEngine: Increase engine speed from
idle speed to 4,000 r/min.Decreases slightly (approx.
0.7V) from 4.5 V - 5.0 V.
99Ignition switch - IGIgnition switch: ONSystem voltage
NOTE
Check if the difference in output between *1 and *2 is 4 V or more.
CHECK CHART FOR RESISTANCE AND CONTINUITY
BETWEEN TERMINALS
1. Turn the ignition switch to OFF.
2. Disconnect the engine-ECU connector.
3. Measure the resistance and check for continuity between
the terminals of the engine-ECU harness-side connector
while referring to the check chart.
NOTE
(1) When measuring resistance and checking continuity,
a harness for checking contact pin pressure should
be used instead of inserting a test probe.
(2) Checking need not be carried out in the order given
in the chart.
Caution
If the terminals that should be checked are mistaken,
or if connector terminals are not correctly shorted
to earth, damage may be caused to the vehicle wiring,
sensors, engine-ECU and/or ohmmeter.
Be careful to prevent this!
4. If the ohmmeter shows any deviation from the standard
value, check the corresponding sensor, actuator and
related electrical wiring, and then repair or replace.
5. After repair or replacement, recheck with the ohmmeter
to confirm that the repair or replacement has corrected
the problem.


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