1997 MITSUBISHI TRITON relay

MPI ± Troubleshooting13A-45
INSPECTION PROCEDURE 31
Idle speed control (ISC) servo (Stepper motor) system
Probable cause
The engine-ECU controls the intake air volume during idling by opening and closing
the servo valve located in the bypass air passage.
Malfunction of ISC servo

Improper connector contact, open circuit or
short-circuited harness wire

Malfunction of the engine-ECU
Check the ISC servo
(Refer to P.13A-90.)NG
Replace
OK
Measure at the ISC servo connector A-50.

Disconnect the connector and measure at the harness side.

Voltage between 2 and earth, and 5 and earth (Ignition switch:
ON)
OK:System voltageNGCheck the harness wire between control relay and ISC servo con-
nector, and repair if necessary.
OK
Measure at the engine-ECU connector C-49.

Disconnect the connector, measure at the harness side.

Voltage between each of 4, 5, 17, 18 and earth (Ignition switch:
ON)
OK:System voltageNGCheck the following
connector. A-50NG
Repair
OK
Check trouble symptom.
NG
Check harness wire between engine-ECU and ISC servo connector,
and repair if necessary.
OK
Check the following
connector. C-49NG
Repair
OK
Check trouble symptom.NGReplace the engine-ECU.
INSPECTION PROCEDURE 32
Purge control solenoid valve system
Probable cause
The purge control solenoid valve controls the purging of air from the canister located
inside the intake manifold.
Malfunction of solenoid valve

Improper connector contact, open circuit or
short-circuited harness wire.

Malfunction of the engine-ECU
Check the purge control solenoid valve.
(Refer to GROUP 17 ± Emission Control System.)NG
Replace
OK
Measure at the purge control solenoid valve connector A-48.

Disconnect the connector and measure at the harness side.

Voltage between 2 and earth (Ignition switch: ON)
OK:System voltageNGCheck the harness wire between control relay and solenoid valve
connector, and repair if necessary.
OK
Measure at the engine-ECU connector B-49.

Disconnect the connector and measure at the harness side.

Voltage between 9 and earth (Ignition switch: ON)
OK:System voltageNGCheck the following
connector. A-48NG
Repair
OK
Check trouble symptom.
NG
Check the harness wire between engine-ECU and solenoid valve
connector, and repair if necessary.
OK
Check the following
connector. B-49NG
Repair
OK
Check trouble symptom.
NG
Replace the engine-ECU.

MPI ± Troubleshooting13A-46
INSPECTION PROCEDURE 33
EGR control solenoid valve system
Probable cause
The EGR control solenoid valve is controlled by the negative pressure resulting from
EGR operation leaking to port ªAº of the throttle body.
Malfunction of solenoid valve

Improper connector contact, open circuit or
short-circuited harness wire.

Malfunction of the engine-ECU
Check the EGR control solenoid valve.
(Refer to GROUP 17 ± Emission Control System.)NG
Replace
OK
Measure at the EGR control solenoid valve connector A-49.

Disconnect the connector and measure at the harness side.

Voltage between 1 and earth (Ignition switch: ON)
OK:System voltageNGCheck the harness wire between control relay and solenoid valve
connector, and repair if necessary.
OK
Measure at the engine-ECU connector C-49.

Disconnect the connector and measure at the harness side.

Voltage between 6 and earth (Ignition switch: ON)
OK:System voltageNGCheck the following
connector. A-49NG
Repair
OK
Check trouble symptom.
NG
Check the harness wire between engine-ECU and solenoid valve
connector, and repair if necessary.
OK
OK
Check trouble symptom.
NG
Replace the engine-ECU.
Check the following
connector. C-49NG
Repair

MPI ± Troubleshooting13A-49
INSPECTION PROCEDURE 38
MUT-II: Check if idling speed is unstable.
OK
MUT-II Data list
26 Idle position switch (Refer to P.13A-57.)NGCheck the idle position switch system.
(Refer to P.13A-40, INSPECTION PROCEDURE 25.)
OK
MUT-II Data list
13 Intake air temperature sensor (Refer to P.13A-57.)NGCheck the intake air temperature sensor system. (Refer to P.13A-12,
INSPECTION PROCEDURE FOR DIAGNOSIS CODE 13.)
OK
MUT-II Data list
25 Barometric pressure sensor (Refer to P.13A-57.)NGCheck the barometric pressure sensor system. (Refer to P.13A-18,
INSPECTION PROCEDURE FOR DIAGNOSIS CODE 25.)
OK
MUT-II Data list
21 Engine coolant temperature sensor (Refer to P.13A-57.)NGCheck the engine coolant temperature sensor system.
(Refer to P.13A-14, INSPECTION PROCEDURE FOR DIAGNOSIS
CODE 21.)
OK
MUT-II Actuator test
08 Purge control solenoid valve (Refer to P.13A-62.)NGCheck the purge control solenoid valve system
(Refer to P.13A-45, INSPECTION PROCEDURE 32.)
MUT-II Data list
11 Oxygen sensor
OK:600 ±1,000 mV during sudden racingNGCheck the oxygen sensor system. (Refer to P.13A-11, INSPECTION
PROCEDURE FOR DIAGNOSIS CODE 11.)
OK
MUT-II Data list
11 Oxygen sensor
OK:Changes between 0 ±400 mV and 600 ±1,000 mV during
idlingNGCheck the fuel pressure.
(Refer to P.13A-81.)OK1. Inspect the intake of
air into the air intake
system.

Broken intake
manifold gasket

Broken vacuum
hose

PCV valve does
not operate.

Broken air intake
hose
2. Check the injector for
clog.
OK
MUT-II Data list
27 Power steering fluid pressure switch (Refer to P.13A-57.)NGCheck the power steering
fluid pressure switch sys-
tem. (Refer to P.13A-43,
INSPECTION PROCE-
DURE 28.)
OK
MUT-II Data list
28 A/C switch (Refer to P.13A-57.)NGCheck the A/C switch and A/C relay system.
(Refer to P.13A-43. INSPECTION PROCEDURE 29.)
OK
MUT-II Data list
29 Inhibitor switch (Refer to P.13A-57.)NGCheck the ignition switch-ST and inhibitor switch system.
(Refer to P.13A-42, INSPECTION PROCEDURE 27.)
OK
MUT-II Data list
45 ISC Servo position (Refer to P.13A-57.)NGAdjust the basic idle speed. (Refer to P.13A-79.)
OK
MUT-II Actuator test
10 EGR control solenoid valve (Refer to P.13A-62.)NGCheck the EGR control solenoid valve system. (Refer to P.13A-46,
INSPECTION PROCEDURE 33.)

MPI ± Troubleshooting13A-50
INSPECTION PROCEDURE 39
MUT-II: Engine stalling inspection when the engine is warmed up and idling.
MUT-II Data list
26 Idle position switch (Refer to P.13A-57.)NGCheck the idle position switch system.
(Refer to P.13A-40, INSPECTION PROCEDURE 25.)
OK
MUT-II Data list
13 Intake air temperature sensor (Refer to P.13A-57.)NGCheck the intake air sensor system. (Refer to P.13A-12, INSPEC-
TION PROCEDURE FOR DIAGNOSIS CODE 13.)
OK
MUT-II Data list
25 Barometric pressure sensor (Refer to P.13A-57.)NGCheck the barometric pressure sensor system. (Refer to P.13A-18,
INSPECTION PROCEDURE FOR DIAGNOSIS CODE 25.)
OK
MUT-II Data list
21 Engine coolant temperature sensor (Refer to P.13A-57.)NGCheck the engine coolant temperature sensor system.
(Refer to P.13A-14, INSPECTION PROCEDURE FOR DIAGNOSIS
CODE 21.)
OK
MUT-II Data list
11 Oxygen sensor
OK:Changes between 0 ± 400 mV and 600 ± 1,000 mV during
idlingNGCheck the fuel pressure.
(Refer to P.13A-81.)OK1. Inspect the intake of
air into the air intake
system

Broken intake
manifold gasket

Broken vacuum
hose

PCV valve does
not operate.

Broken air intake
hose
2. Check the injector for
clog.
OK
MUT-II Data list
27 Power steering fluid pressure switch (Refer to P.13A-57.)NGCheck the power steering
fluid pressure switch sys-
tem. (Refer to P.13A-43,
INSPECTION PROCE-
DURE 28.)
OK
MUT-II Data list
28 A/C switch (Refer to P.13A-57.)NGCheck the A/C switch and A/C relay system.
(Refer to P.13A-43, INSPECTION PROCEDURE 29.)
OK
MUT-II Data list
29 Inhibitor switch (Refer to P.13A-57.)NGCheck the ignition switch-ST and inhibitor switch system.
(Refer to P.13A-42, INSPECTION PROCEDURE 27.)
OK
MUT-II Data list
45 ISC servo position (Refer to P.13A-57.)NGAdjust the basic idle speed. (Refer to P.13A-79.)
OK
MUT-II Actuator test
10 EGR control solenoid valve (Refer to P.13A-62.)NGCheck the EGR control solenoid valve system. (Refer to P.13A-46,
INSPECTION PROCEDURE 33.)
OK
MUT-II Data list
11 Oxygen sensor
OK:Changes between 600 ± 1,000 mV during sudden racingNGCheck the oxygen sensor system. (Refer to P.13A-11, INSPECTION
PROCEDURE FOR DIAGNOSIS CODE 11.)

MPI ± Troubleshooting13A-53
INSPECTION PROCEDURE 42
Check the engine-ECU power supply and earth circuit.
OK
Check trouble symptom.
OK
Check the harness wire
between engine-ECU and
ignition switch connector.NG
Repair
OK
Check the ignition switch.
(Refer to GROUP 54 ± Ignition Switch and Immobilizer System.)
4. NG
Check the harness wire between engine-ECU and earth, and repair
if necessary.
5. NG
OK
Check the following
connectors.
C-49, C-50, C-51NG
Repair
OK
Check trouble symptom.
NG
Replace the engine-ECU.
Check the following connectors.
A-56X, C-19, C-81, C-87NG
Repair
OK
Check trouble symptom
NG
Check the harness wire between engine-ECU and battery, and
repair if necessary.
NG
Check the harness wire between the engine-ECU and control relay,
and repair if necessary.
OK
Check trouble symptom.
2, 3. NG
Check the following
connector. C-53NG
Repair
Measure the engine-ECU connectors, C-49, C-50, C-51.

Disconnect the connector and measure at the harness side
1. Voltage between 62 and earth (Ignition switch: ON)
OK:System voltage
2. Voltage between 38 and earth
OK:System voltage
3. Voltage between 12, 25 and earth (Ignition switch: ON)
OK:System voltage (when the terminal 38 is earthed)
4. Continuity between 13, 26 and earth
OK:Continuity
5. Voltage between 60 and earth
OK:System voltage1. NGCheck the following
connector. C-88NG
Repair
INSPECTION PROCEDURE 43
Check fuel pump circuit.
Measure at the fuel pump connector F-17.

Disconnect the connector and measure at the harness side.

Continuity between 2 and earth
OK:ContinuityNGCheck the following connectors.
D-02, F-17NG
Repair
OK
Check trouble symptom
NG
Check the harness wire between fuel pump and earth, and repair
if necessary.
OK
Check the following connectors. C-19, D-02, F-17NG
Repair OKCheck trouble symptom.
NG
Check the harness wire between terminal for fuel pump drive and
fuel pump connector.NG
Repair
OK
Replace the fuel pump.

MPI ± Troubleshooting13A-54
INSPECTION PROCEDURE 44
Check the fuel pump drive control circuit.
Measure at the fuel pump relay connector C-54.

Disconnect the connector and measure at the harness side.

Voltage between 4 and earth (Ignition switch: ON)
OK:System voltageNGCheck the following
connector. C-88NG
Repair
OK
Check trouble symptom.
NG
Check the harness wire
between fuel pump relay
and ignition switch con-
nector.NG
Repair
OK
Check the ignition switch.
(Refer to GROUP 54 ± Ignition Switch and Immobilizer System.)
OK
Measure at the engine-ECU connector C-49.

Disconnect the connector and measure at the harness side.


Voltage between 8 and earth (Ignition switch: ON)
OK:System voltage


Voltage between 22 and earth (Ignition switch: ON)
OK:System voltageNG
Check the following
connector. C-54NG
Repair
OK
Check trouble symptom.
NG
Check the harness wire between engine-ECU and fuel pump relay
connector, and repair if necessary.
OK
Check the following connector. C-49NG
Repair
OK
Check trouble symptom.
NG
Replace the engine-ECU.
INSPECTION PROCEDURE 45
Check air flow sensor (AFS) control circuit.
Measure at the air flow sensor connector A-77.

Disconnect the connector and measure at the harness side.
1. Voltage between 4 and earth (Ignition switch: ON)
OK:System voltage
2. Voltage between 3 and earth (Ignition switch: ON)
OK:4.8 ± 5.2 V
3. Continuity between 5 and earth
OK:Continuity1. NGCheck the harness wire between the air flow sensor and control
relay connector, and repair if necessary.
2, 3. NGCheck the following
connector. C-51NG
Repair
OK
Check trouble symptom.
NG
Check the harness wire
between the engine-ECU
and air flow sensor con-
nector.NG
Repair
OK
Replace the engine-ECU.
OK
Check the following connector. A-77NG
Repair
OK
Check trouble symptom.
NG
Replace the air flow sensor.

MPI ± Troubleshooting13A-61
Item
No.Reference
page Inspection
procedure
No. Normal condition Inspection contents Inspection
item
45ISC
(stepper)
motor
p
osition*5

Engine coolant
temperature:
80 ± 95C

Lamps and all
A/C switch: OFF2 ± 25 STEP±±
osition 5
Lam s and all
accessories: OFF

Transmission:
Neutral (A/T :
P range)

Idleposition
A/C switch:
OFF
ONIncreases by
10 ± 70 steps

Idle osition
switch: ON

Engine: Idling

When A/C switch
is ON, A/C
compressor should
be operating
A/C switch: OFF

Select lever:
N range
D
rangeIncreases by
5 ± 50 steps
49A/C relayEngine: After having
warmed up/Engine is
idlingA/C switch: OFFOFF (Compressor
clutch is not
operating)Procedure
No. 2913A-43
A/C switch: ONON (Compressor
clutch is
operating)

MPI ± Troubleshooting13A-65
Terminal No.Normal condition Check condition (Engine condition) Check item
35Oxygen sensor heaterEngine: Idling after warming up0±3V
Engine r/min: 5,000r/min.System voltage
36Engine warning lampIgnition switch: OFF
ON0 ± 3V
9 ± 13V
(After several seconds have
elapsed)
37Power steering fluid
pressure switchEngine: Idling after
warming upWhen steering
wheel is stationarySystem voltage
When steering
wheel is turned0±3V
38Control relay
(Power supply)
Ignition switch: OFFSystem voltage
(Power su ly)
Ignition switch: ON0±3V
45A/C switchEngine: Idle speedTurn the A/C
switch OFF0±3V
Turn the A/C
switch ON (A/C
compressor is
operating)System voltage
51Ignition switch ± STEngine: Cranking8V or more
52Intake air temperature
sensorIgnition switch:
ONWhen intake air
temperature is
0
C3.2 ± 3.8V
When intake air
temperature is
20
C2.3 ± 2.9V
When intake air
temperature is
40
C1.5 ± 2.1V
When intake air
temperature is
80
C0.4 ± 1.0V
56Oxygen sensorEngine: Running at 2,500 r/min after
warmed up (Check using a digital type
voltmeter)0
0.8V
(Changes repeatedly)
60Backup power supplyIgnition switch: OFFSystem voltage
61Sensor impressed
voltageIgnition switch: ON4.5 ± 5.5V
62Ignition switch ± IGIgnition switch: ONSystem voltage