air condition MITSUBISHI TRITON 1997 User Guide

MPI ± Troubleshooting13A-18
Code No. 25 Barometric pressure sensor systemProbable cause
Range of Check

Ignition switch: ON

Excluding 60 seconds after the ignition switch is turned to ON or immediately
after the engine starts.

Battery voltage is 8 V or more.
Set conditions

Sensor output voltage is 4.5 V or more (corresponding to a barometric pressure
of 114 kPa or more) for 4 seconds.
or

Sensor output voltage is 0.2 V or less (corresponding to a barometric pressure
of 5.33 kPa or less) for 4 seconds.
Malfunction of the barometric pressure sensor

Improper connector contact, open circuit or
short-circuited harness wire of the barometric pressure
sensor circuit

Malfunction of the engine-ECU
Measure at the air flow sensor con-
nector A-77.

Connect the connector. (Use
the test harness: MB991348)

Voltage between 2 and earth
(Ignition switch: ON)
OK:3.7 ± 4.3 V (Altitude: 0 m)
3.2 ± 3.8 V (Altitude:
1,200 m)NGMeasure at the air flow sensor con-
nector A-77.

Disconnect the connector, and
measure at the harness side.

Voltage between 1 and earth
(Ignition switch: ON)
OK:4.8 ± 5.2 V

Continuity between 5 and earth
OK:ContinuityNGCheck the following connector.
C-51NG
Repair
OK
Check trouble symptom.
NG
Check the harness wire between
the engine-ECU and the baromet-
ric pressure sensor connector.NG
Repair
OK
Replace the engine-ECU.
OK
Check the following connector.
A-77NG
Repair
OK
Check trouble symptom.
NG
Check the harness wire between
the engine-ECU and the baromet-
ric pressure sensor connector.NG
Repair
OK
Replace the air flow sensor.
OK
Measure at the engine-ECU con-
nector C-51.

Connect the connector.

Voltage between 65 and earth
(Ignition switch: ON)
OK:3.7 ± 4.3 V (Altitude: 0 m)
3.2 ± 3.8 V (Altitude:
1,200 m)NGCheck the harness wire between
the engine-ECU and the baromet-
ric pressure sensor connector, and
repair if necessary.
Check the following connector.
C-51
OK
Check trouble symptom.
NG
Replace the engine-ECU.NG
Repair OK

MPI ± Troubleshooting13A-19
Code No. 36 Ignition timing adjustment signal systemProbable cause
Range of Check

Ignition switch: ON
Set conditions

The ignition timing adjusting signal wire is shorted to the earth.
Short circuit to earth of the ignition timing adjustment
signal line

Malfunction of the engine-ECU
Measure at the ignition timing adjust-
ment connector A-42.

Measurement of the voltage (Ignition
switch: ON)
OK:4.0 ± 5.2 VNGCheck the following connector. C-50NG
Repair
OK
Check trouble symptom.
NG
Check the harness wire between the
engine-ECU connector and the ignition
timing adjustment terminal.NG
Repair
OK
Replace the engine-ECU.
OK
Replace the engine-ECU.
Code No. 41 Injector systemProbable cause
Range of Check

Engine speed is approx. 50 ± 1,000 r/min

The throttle position sensor output voltage is 1.15 V or less.

Actuator test by MUT-II is not carried out.
Set conditions

Surge voltage of injector coil is not detected for 4 seconds.
Malfunction of the injector

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

Malfunction of the engine-ECU
Check the injector. (Refer to P.13A-89.)NG
Replace
OK
Measure at the injector connectors.
A-45, A-46, A-57, A-61.

Disconnect the connector, and
measure at the harness side.

Voltage between 1 and earth
(Ignition switch: ON)
OK:System voltageNGCheck the following connectors.
A-45, A-46, A-57, A-61.NG
Repair
OK
Check trouble symptom.NGCheck the harness wire between the
engine-ECU and the injector connector,
and repair if necessary.
Check the injector control circuit.
(Refer to P.13A-55, INSPECTION PRO-
CEDURE 47.)OK

MPI ± Troubleshooting13A-20
Code No.54 Immobilizer systemProbable cause
Range of Check

Ignition switch: ON
Set Conditions

Improper communication between the engine-ECU and immobilizer-ECU
Radio interference of ID codes

Incorrect ID code

Malfunction of harness or connector

Malfunction of immobilizer-ECU

Malfunction of engine-ECU
NOTE
(1) If the ignition switches are close each other when starting the engine, radio interference may cause
this code to be displayed.
(2) This code may be displayed when registering the key ID code.
No
Is there another ignition key near the ignition key that is inserted
in the ignition switch?Ye sRemove the extra ignition key.
NGCheck trouble symptom.
Is a diagnosis code output from the immobilizer-ECU?Ye sCheck the immobilizer system. (Refer to GROUP 54 ± Ignition
Switch and Immobilizer System.)
No
Check the following connectors.
C-19, C-36, C-50NG
Repair
OK
Check trouble symptom.
NG
Check the harness wire between the engine-ECU and the immobiliz-
er-ECU.OKReplace the immobilizer-ECU.
NG
Check trouble symptom.NG
RepairNG
Replace the engine-ECU.

MPI ± Troubleshooting13A-40
INSPECTION PROCEDURE 24
Fuel pump system
Probable cause
The engine-ECU turns the control relay ON when the engine is cranking or running,
and this supplies power to drive the fuel pump.
Malfunction of the fuel pump relay

Malfunction of the fuel pump

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

Malfunction of the engine-ECU
Check the fuel pump operation. (Refer to P.13A-84.)NGCheck the fuel pump circuit.
(Refer to P.13A-53, INSPECTION PROCEDURE 43.)
OK
Check the fuel pump relay. (Refer to P.13A-86.)NG
Replace
OK
Measure at the fuel pump relay connector C-54.

Connect the connector.

Voltage between 1 and earth

MUT-II Actuator test: Fuel pump drive
OK:System voltageNGCheck the fuel pump drive control circuit.
(Refer to P.13A-54, INSPECTION PROCEDURE 44.)
OK
Check the harness wire between fuel pump relay connector and
fuel pump drive terminal, and repair if necessary.
INSPECTION PROCEDURE 25
Idle position switch system
Probable cause
The idle position switch inputs the condition of the accelerator pedal, i.e. whether
it is depressed or released (HIGH/LOW), to the engine-ECU.
The engine-ECU controls the idle speed control servo based on this input.
Maladjustment of the accelerator pedal

Maladjustment of the fixed SAS

Maladjustment of the idle position switch and throttle
position sensor

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

Malfunction of the engine-ECU
Check the idle position switch. (Refer to P.13A-87.)NGReplace
OK
Measure at the throttle position sensor connector A-47.

Disconnect the connector, and measure at the harness side.

Voltage between 2 and earth (Ignition switch: ON)
OK:4 V or higher

Continuity between 1 and earth
OK:ContinuityNGCheck the following
connector. C-51NG
Repair
OK
Check trouble symptom.
NG
Check the harness wire between engine-ECU and throttle position
sensor connector.
OK
Replace the engine-ECU.
NG
Repair
OK
Check the following
connector. A-47NG
Repair
OK
Check trouble symptom.
NG
Replace the engine-ECU.

MPI ± Troubleshooting13A-42
INSPECTION PROCEDURE 27
Ignition switch-ST and inhibitor switch system
Probable cause

The ignition switch-ST inputs a HIGH signal to the engine-ECU while the engine
is cranking.
The engine-ECU controls fuel injection, etc. during starting based on this input.

The inhibitor switch inputs the condition of the select lever, i.e. whether it is in
P or N range or in some other range, to the engine-ECU.
The engine-ECU controls the idle speed control (ISC) servo based on this input.
Malfunction of ignition switch

Malfunction of inhibitor switch

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

Malfunction of the engine-ECU.
Check the following
connector. B-01
OK
Measure at the inhibitor switch connector B-01.

Disconnect the connector, and measure at the harness side.
1. Voltage between 6 and earth (Ignition switch: ON)
OK:System voltage
2. Continuity between 5 and earth
OK:Continuity
3. Voltage between 6 and earth

Ignition switch: START

Disconnect engine-ECU connector.
OK:System voltage1. NGCheck the following
connectors.
C-01, C-51, C-57NG
Repair
OK
Check trouble symptom. 2. NG
3. NG
Check the following
connector.
C-01, C-57, C-70NG
Repair
OK
Check trouble symptom.
NG
NG
Repair
Check harness wire be-
tween inhibitor switch and
ignition switch connector.
OK
Check the ignition switch.
(Refer to GROUP 54 ± Ignition Switch and Immobilizer system.)
OK
NG
Repair
OK
Check trouble symptom.
NG
Check harness wire be-
tween engine-ECU and
inhibitor switch connector.NG
Repair
OK
Replace the engine-ECU.
NG
ReplaceCheck the inhibitor switch.
(Refer to GROUP 23 ± On-vehicle Service.)
NG
Check the harness wire
between the engine-ECU
connector and inhibitor
switch connector.NG
Repair
OK
Replace the engine-ECU.
OK
Check trouble symptom.
NG
Check the harness wire between the inhibitor switch connector
and earth, and repair if necessary.
Check the following
connectors.
A-52X, C-19, C-57NG
Repair

MPI ± Troubleshooting13A-57
DATA LIST REFERENCE TABLE13100890180
Caution
When shifting the select lever to D range, the brakes should be applied so that the vehicle does
not move forward.
NOTE
*1. In a new vehicle [driven approximately 500 km or less], the air flow sensor output frequency is sometimes
10% higher than the standard frequency.
*
2. The idle position switch normally turns off when the voltage of the throttle position sensor is 50 ±
100 mV higher than the voltage at the idle position. If the idle position switch turns back on after
the throttle position sensor voltage has been by 100 mV and the throttle valve has been opened,
the idle position switch and the throttle position sensor need to be adjusted.
*3. The injector drive time represents the time when the cranking speed is at 250 r/min or below when
the power supply voltage is 11 V.
*4. In a new vehicle [driven approximately 500 km or less], the injector drive time is sometimes 10%
longer than the standard time.
*5. In a new vehicle [driven approximately 500 km or less], the step of the stepper motor is sometimes
30 steps greater than the standard value.
Item
No.Inspection
itemInspection contentsNormal conditionInspection
procedure
No.Reference
page
11Oxygen
sensorEngine:After having
warmed up
Air/fuel mixture is
made leaner when de-
When at 4,000 r/min,
engine is suddenly
decelerated200 mV or lessCode No.
1113A-11
made leaner when de-
celerating, and is made
richer when racing.
When engine is
suddenly raced600 ± 1,000 mV
Engine:After having
warmed up
The oxygen sensor
signal is used to check
the air/fuel mixture
ratio and control
Engine is idling400 mV or less
(Changes)
600 ± 1,000 mV
ratio, and control
condition by the en-
gine-ECU.2,500 r/min400 mV or less
(Changes)
600 ± 1,000 mV
12Air flow
sensor*1
Engine coolant
temperature:
80 ± 95C

Lamps and all
accessories: OFF
Engine is idling22 ± 48 Hz
<4G63>
19 ± 45 Hz
<4G64>±±
accessories: OFF

Transmission:
Neutral (A/T:
P range)2,500 r/min80 ± 120 Hz
<4G63>
67 ± 107 Hz
<4G64>
Engine is racedFrequency
increases in
response to
racing

MPI ± Troubleshooting13A-58
Item
No.Reference
page Inspection
procedure
No. Normal condition Inspection contents Inspection
item
13Intake air
temperature
sensor
Ignition switch: ON or
with engine runningWhen intake air
temperature is ±20
C±20
CCode No.
1313A-12
sensorWhen intake air
temperature is 0
C0
C
When intake air
temperature is 20
C20
C
When intake air
temperature is 40
C40
C
When intake air
temperature is 80
C80
C
14Throttle
p
osition
Ignition switch: ONSet to idle position300 ± 1,000 mVCode No.
14
13A-13
osition
sensorGradually openIncreases in
proportion to
throttle opening
angle
14
Open fully4,500 ± 5,500 mV
16Power
supply
voltageIgnition switch: ONSystem voltageProcedure
No. 2313A-39
18Cranking
signal
(ignition
it h ST)
Ignition switch: ONEngine: StoppedOFFProcedure
No. 26
13A-41

13A-42
switch-ST)Engine: CrankingONProcedure
No. 27

21Engine
coolant
temperature
sensor
Ignition switch: ON or
with engine runningWhen engine
coolant temperature
is ±20
C±20
CCode No.
2113A-14
sensor
When engine
coolant temperature
is 0
C0
C
When engine
coolant temperature
is 20
C20
C
When engine
coolant temperature
is 40
C40
C
When engine
coolant temperature
is 80
C80
C

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

MPI ± TroubleshootingMPI ± Troubleshooting13A-66
Terminal No.Normal condition Check condition (Engine condition) Check item
63Engine coolant
temperature sensorIgnition switch:
ONWhen engine
coolant tempera-
ture is 0C3.2 ± 3.8V
When engine
coolant tempera-
ture is 20C2.3 ± 2.9V
When engine
coolant tempera-
ture is 40C1.3 ± 1.9V
When engine
coolant tempera-
ture is 80C0.3 ± 0.9V
64Throttle position
sensorIgnition switch:
ONSet throttle valve
to idle position0.3 ± 1.0V
Fully open throttle
valve4.5 ± 5.5V
65Barometric pressure
sensorIgnition switch:
ONWhen altitude is
0m3.7 ± 4.3V
When altitude is
1,200m3.2 ± 3.8V
66Vehicle speed sensor
Ignition switch: ON

Move the vehicle slowly forward0
5V
(Changes repeatedly)
67Idle position switchIgnition switch:
ONSet throttle valve
to idle position0±1V
Slightly open
throttle valve4V or more
68Top dead centre sensorEngine: Cranking0.4 ± 3.0V
Engine: Idle speed0.5 ± 2.0V
69Crank angle sensorEngine: Cranking0.4 ± 4.0V
Engine: Idle speed1.5 ± 2.5V
70Air flow sensorEngine: Idle speed2.2 ± 3.2V
Engine r/min: 2,500r/min
71Inhibitor switch Ignition switch:
ONSet selector lever
to P or N0±3V
Set selector lever
to Other than P or
N8 ± 14V

MPI ± Troubleshooting13A-68
Terminal No. Normal condition (Check condition)Inspection item
4±12Stepper motor coil (A1)28 ± 33 W (At 20
C)
17 ± 12Stepper motor coil (A2)
5±12Stepper motor coil (B1)
18 ± 12Stepper motor coil (B2)
6±12EGR control solenoid valve36 ± 44 W (At 20
C)
9±12Purge control solenoid valve36 ± 44 W (At 20
C)
13 ± Body earthEngine-ECU earthContinuity (0W)
26 ±Body earthEngine-ECU earth
35 ± 12Oxygen sensor heaterApprox. 12 W (At 20
C)
52 ± 72Intake air temperature sensor5.3 ± 6.7 kW (When intake air temperature is 0
C)
2.3 ± 3.0 kW (When intake air temperature is 20
C)
1.0 ± 1.5 kW (When intake air temperature is 40
C)
0.30 ± 0.42 kW (When intake air temperature is 80
C)
63 ± 72Engine coolant temperature sensor5.1 ± 6.5 kW (When coolant temperature is 0
C)
2.1 ± 2.7 kW (When coolant temperature is 20
C)
0.9 ± 1.3 kW (When coolant temperature is 40
C)
0.26 ± 0.36 kW (When coolant temperature is 80
C)
67 ± 72Idle position switchContinuity (when throttle valve is at idle position)
No continuity (when throttle valve is slightly open)
71 ±Body earthInhibitor switch Continuity (when select lever is at P or N)
No continuity (when select lever is at D, 2, L or R)