check engine MITSUBISHI TRITON 1997 User Guide

MPI ± Troubleshooting13A-11
INSPECTION PROCEDURE FOR DIAGNOSIS CODES
Code No. 11 Oxygen sensor systemProbable cause
Range of Check

3 minutes have passed after engine was started.

Engine coolant temperature is approx. 80C or more.

Intake air temperature is 20 ± 50C.

Engine speed is approx. 2,000 ± 3,000 r/min

Vehicle is moving at constant speed on a flat, level road surface
Set conditions

The oxygen sensor output voltage is around 0.6 V for 30 seconds (does not cross
0.6 V for 30 seconds).

When the range of check operations given above which accompany starting of
the engine are carried out four time in succession, a problem is detected after
each operation.
Malfunction of the oxygen sensor

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

Malfunction of the engine-ECU
Check the oxygen sensor. (Refer to P.13A-88.)NG
Replace
OK
Measure at the oxygen sensor connector B-03.

Disconnect the connector, and measure at the
harness side.
1. Voltage between 1 and earth (Ignition switch: ON)
OK:System voltage
2. Continuity between 2 and earth
OK:Continuity
OK1. NG
Check the harness wire between the
oxygen sensor and the control relay
connector, and repair if necessary.
2. NG
Check the following connector.
C-51, C-60NG
Repair
OK
Check trouble symptom.
NG
Check the harness wire between the
engine-ECU and the oxygen sensor
connector.NG
Repair
OK
Replace the engine-ECU.
Measure at the engine-ECU connector C-50.

Disconnect the connector, and measure at the
harness side.

Voltage between 35 and earth (Ignition switch: ON)
OK:System voltage
NGCheck the following connector.
B-03, C-60NG
Repair
OK
Check the following connectors.
B-03, C-50NG
RepairCheck trouble symptom.OK
OKNGCheck the harness wire between the
engine-ECU and the oxygen sensor
connector, and repair if necessary.
Check trouble symptom.
NG
Check the harness wire between the engine-ECU and
the oxygen sensor connector.NG
Repair
OK
Replace the engine-ECU.

MPI ± Troubleshooting13A-12
Code No. 12 Air flow sensor systemProbable cause
Range of Check

Engine speed is 500 r/min or more.
Set conditions

Sensor output frequency is 3 Hz or less for 4 seconds.
Malfunction of the air flow sensor

Improper connector contact, open circuit or
short-circuited harness wire of the air flow sensor

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

Connect the connector. (Use
the test harness: MB991348)
1. Voltage between 3 and earth
(Engine: Idling)
OK:2.2 ± 3.2 V
2. Voltage between 7 and earth
OK:0 ± 1 V (Engine: idling)
6 ± 9 V (2,000 r/min)
OK
Replace the engine-ECU.1. NG
Check the air flow sensor circuit.
(Refer to P.13A-54, INSPECTION
PROCEDURE 45.)
2. NG
Measure at the engine-ECU con-
nector C-49.

Connect the connector.

Voltage between 19 and earth
(Ignition switch: ON)
OK:6±9 V
OK
Check the following connector.
C-49
OK
Check trouble symptom.
NG
Replace the engine-ECU.NG
Check the following connector.
A-77NG
Repair
OK
Check trouble symptom.
NG
NG
Repair
Replace the air flow sensor.
Code No. 13 Intake air temperature 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.
Set conditions

Sensor output voltage is 4.6 V or more (corresponding to an intake air temperature
of ±45C or less) for 4 seconds.
or

Sensor output voltage is 0.2V or less (corresponding to an intake air temperature
of 125C or more) for 4 seconds.
Malfunction of the intake air temperature sensor

Improper connector contact, open circuit or
short-circuited harness wire of the intake air
temperature sensor circuit

Malfunction of the engine-ECU
Check the intake air temperature
sensor.
(Refer to P.13A-86.)NG
Replace
OK
Measure at the air flow sensor con-
nector A-77.

Disconnect the connector, and
measure at the harness side.

Voltage between 6 and earth
(Ignition switch: ON)
OK:4.5 ± 4.9 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 intake air
temperature sensor connector.NG
Repair
OK
Replace the engine-ECU. OK
Check the following connector.
A-77NG
Repair
OK
Check trouble symptom.NGReplace the engine-ECU.

MPI ± Troubleshooting13A-13
Code No. 14 Throttle position 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.
Set conditions

When the idle position switch is ON, the sensor output voltage is 2 V or more
for 4 seconds.
or

The sensor output voltage is 0.2 V or less for 4 seconds.
Malfunction of the throttle position sensor or
maladjustment

Improper connector contact, open circuit or
short-circuited harness wire of the throttle position
sensor circuit

Improper ªONº state of idle position switch

Short circuit of the idle position switch signal line

Malfunction of the engine-ECU
MUT-II Data list
26 Idle position switch system
OK:With the throttle valve at the
idle position: ON
With the throttle valve slight-
ly open: OFFNGCheck the idle position switch system.
(Refer to P.13A-40 INSPECTION
PROCEDURE 25.)
OK
Check the throttle position sensor.
(Refer to P.13A-87.)NG
Replace
OK
Measure at the throttle position sensor
connector A-47.

Disconnect the connector, and
measure at the harness side.

Voltage between 4 and earth
(Ignition switch: ON)
OK:4.8 ± 5.2 V

Continuity between 1 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 throttle position
sensor connector.NG
Repair
OK
Replace the engine-ECU. OK
Check the throttle position sensor out-
put circuit. (Refer to P.13A-55, IN-
SPECTION PROCEDURE 46.)

MPI ± Troubleshooting13A-14
Code No. 21 Engine coolant temperature 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.
Set conditions

Sensor output voltage is 4.6 V or more (corresponding to an engine coolant
temperature of ±45C or less) for 4 seconds.
or

Sensor output voltage is 0.1 V or less (corresponding to an engine coolant
temperature of 140C or more) for 4 seconds.
Malfunction of the engine coolant temperature sensor

Improper connector contact, open circuit or
short-circuited harness wire of the engine coolant
temperature sensor circuit

Malfunction of the engine-ECU
Range of Check

Ignition switch: ON

Engine speed is approx. 50 r/min or more
Set conditions

The sensor output voltage increases from 1.6 V or less (corresponding to an
engine coolant temperature of 40C or more) to 1.6 V or more (corresponding
to an engine coolant temperature of 40C or less).

After this, the sensor output voltage is 1.6 V or more for 5 minutes.
Check the engine coolant temperature
sensor. (Refer to P.13A-86.)NG
Replace
OK
Measure at the engine coolant temper-
ature sensor connector A-64.

Disconnect the connector, and
measure at the harness side.

Voltage between 1 and earth
(Ignition switch: ON)
OK:4.5 ± 4.9 V

Continuity between 2 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 engine coolant
temperature sensor connector.NG
Repair
OK
Replace the engine-ECU.
Check the following connector.
A-64OKCheck trouble symptom.
NG
Replace the engine-ECU.NG
RepairOK

MPI ± Troubleshooting13A-15
Code No. 22 Crank angle sensor systemProbable cause
Range of Check

Engine is cranking.
Set conditions

Sensor output voltage does not change for 4 seconds (no pulse signal input.)
Malfunction of the crank angle sensor

Improper connector contact, open circuit or
short-circuited harness wire of the crank angle sensor

Malfunction of the engine-ECU
Measure at the distributor connector A-72.

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

Voltage between 2 and earth (Engine: cranking)
OK:0.4 ± 4.0 V

Voltage between 2 and earth (Engine: idling)
OK:1.5 ± 2.5 V
NGOKReplace the engine-ECU.
Measure at the distributor connector A-72.

Disconnect the connector, and measure at the harness side.
1. Voltage between 3 and earth (Ignition switch: ON)
OK:System voltage
2. Voltage between 2 and earth (Ignition switch: ON)
OK:4.8 ± 5.2 V
3. Continuity between 4 and earth
OK:Continuity
OK
Check the following con-
nector. A-72NG
Repair
OK
Check trouble symptom.
NG
Replace the distributor.1. NG
Check the harness wire between the crank angle sensor and the
control relay connector, and repair if necessary.
2. NGCheck the following con-
nector. C-51NG
Repair
OK3. NG
Check trouble symptom.
NG
Check the harness wire
between the engine-ECU and
the distributor connector.NG
Repair
OK
Replace the engine-ECU.
Check the harness wire between the crank angle sensor and the
earth, and repair if necessary.

MPI ± Troubleshooting13A-16
Code No. 23 Top dead centre sensor systemProbable cause
Range of Check

Ignition switch: ON

Engine speed is approx. 50 r/min or more.
Set conditions

Sensor output voltage does not change for 4 seconds (no pulse signal input.)
Malfunction of the camshaft position sensor

Improper connector contact, open circuit or
short-circuited harness wire of the top dead centre
sensor circuit

Malfunction of the engine-ECU
Measure at the distributor connector A-72.

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

Voltage between 1 and earth (Engine: cranking)
OK:0.4 ± 3.0 V

Voltage between 1 and earth (Engine: idling)
OK:0.5 ± 2.0 VOKReplace the engine-ECU.
NG
Measure at the distributor connector A-72.

Disconnect the connector, and measure at the harness side.
1. Voltage between 3 and earth (Ignition switch: ON)
OK:System voltage
2. Voltage between 1 and earth (Ignition switch: ON)
OK:4.8 ± 5.2 V
3. Continuity between 4 and earth
OK:Continuity1. NGCheck the harness wire between the top dead centre sensor and
the control relay connector, and repair if necessary.
2. NGCheck the following con-
nector. C-51NG
Repair
OK
Check trouble symptom.
NG
Check the harness wire
between the engine-ECU and
the distributor connector.NG
Repair
OK
Replace the engine-ECU. 3. NG
OK
Check the following con-
nector. A-72NG
Repair
OK
Check trouble symptom.
NG
Replace the distributor.
Check the harness wire between the top dead centre sensor and
the earth, and repair if necessary.

MPI ± Troubleshooting13A-17
Code No. 24 Vehicles speed 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.

Idle position switch: OFF

Engine speed is 3,000 r/min or more.

Driving under high engine load conditions.
Set conditions

Sensor output voltage does not change for 4 seconds (no pulse signal input).
Malfunction of the vehicle speed sensor

Improper connector contact, open circuit or
short-circuited harness wire of the vehicle speed
sensor circuit

Malfunction of the engine-ECU
Check the vehicle speed sensor. (Refer to GROUP 54 ± Combina-
tion Meters.)NG
Replace
OK
Measure at the combination meter connector C-06, C-07.

Disconnect the connector and measure st the harness side.
1. Voltage between 51 and earth (Ignition switch: ON)
OK: 4.8 ± 5.2 V
2. Continuity between 34 and earth
OK: Continuity1. NGCheck the following
connectors.
C-19, C-51NG
Repair
OK
Check trouble symptom.
NG
Check the harness wire
between the engine-ECU
and the combination me-
ter connector.NG
Repair
OK
Replace the engine-ECU.
2. NG
Check the harness wire between the combination meter and the
earth, and repair if necessary.
OK
Check the following
connectors.
C-06, C-07, C-19NG
Repair
OK
Check trouble symptom.
NG
Check the harness wire
between the engine-ECU
and the combination me-
ter connector.NG
Repair
OK
Replace the engine-ECU.

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.