sensor MITSUBISHI TRITON 1997 User Guide

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-25
INSPECTION PROCEDURE 3
The engine warning lamp does not illuminate right after
the ignition switch is turned to the ON position.
Probable cause
Because there is a burnt-out bulb, the engine-ECU causes the engine warning lamp
to illuminate for five seconds immediately after the ignition switch is turned to ON.
If the engine warning lamp does not illuminate immediately after the ignition switch
is turned to ON, one of the malfunctions listed at right has probably occurred.
Burnt-out bulb

Defective warning lamp circuit

Malfunction of the engine-ECU
MUT-II Data list
16 engine-ECU power supply voltage (Refer to P.13A-58.)NGCheck the engine-ECU power supply and earth circuit.
(Refer to P.13A-53, INSPECTION PROCEDURE 42.)
OK
Measure at the engine-ECU connector C-50.

Disconnect the connector, and measure at the harness side.

Earth the terminal No. 36.
OK:The engine warning lamp illuminates.OKCheck the following
connector. C-50.NG
Repair
OK
Check trouble symptom.
NG
Replace the engine-ECU.
NG
Check a burnt-out bulb.NG
Replace
OK
Measure at the combination meter connector C-06.

Disconnect the connector, and measure at the harness side.

Voltage between 43 and earth (Ignition switch: ON)
OK:System voltageNGCheck the engine warning lamp power supply circuit, and repair
if necessary.
OK
Check the following connectors.
C-04, C-06, C-19, C-50NG
Repair
OK
Check trouble symptom.NGCheck the harness wire between combination meter and engine-
ECU, and repair if necessary.
INSPECTION PROCEDURE 4
The engine warning lamp remains illuminating and never
goes out.
Probable cause
In cases such as the above, the cause is probably that the engine-ECU is detecting
a problem in a sensor or actuator, or that one of the malfunctions listed at right has
occurred.
Short-circuit between the engine warning lamp and
engine-ECU

Malfunction of the engine-ECU
MUT-II Self-Diag code
Are diagnosis codes displayed?Ye sRefer to P.13A-10, INSPECTION CHART FOR DIAGNOSIS
CODES
No
Measure at the combination meter connector C-04.

Disconnect the connector, and measure at the harness side.

Disconnect the engine-ECU connector

Continuity between 8 and earth
OK:No continuityNGCheck the harness wire between combination meter and engine-
ECU connector, and repair if necessary.
OK
Replace the engine-ECU.

MPI ± Troubleshooting13A-30
INSPECTION PROCEDURE 9
Idling speed is high. (Improper idling speed)
Probable cause
In such cases as the above, the cause is probably that the intake air volume during
idling is too great.
Malfunction of the ISC servo system

Malfunction of the throttle body
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.)
No
Check the ISC servo for operation sound. (Refer to P.13A-90.)NGCheck the ISC servo system.
(Refer to P.13A-45, INSPECTION PROCEDURE 31.)
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
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
Basic idle adjustment (Refer to P.13A-79.)
Check trouble symptom.NGClean the throttle valve area. (Refer to P.13A-78.)
Check and adjust the fixed SAS. (Refer to P.13A-79.)
MUT-II Self-Diag code
Are diagnosis codes displayed?Ye sRefer to P.13A-10, INSPECTION CHART FOR DIAGNOSIS
CODES.

MPI ± Troubleshooting13A-31
INSPECTION PROCEDURE 10
Idling speed is low. (Improper idling speed)
Probable cause
In cases such as the above, the cause is probably that the intake air volume during
idling is too small.
Malfunction of the ISC servo system

Malfunction of the throttle body
MUT-II Self-Diag code
Are diagnosis codes displayed?Ye sRefer to P.13A-10, INSPECTION CHART FOR DIAGNOSIS
CODES.
No
Check the ISC servo for operation sound. (Refer to P.13A-90.)NGCheck the ISC servo system.
(Refer to P.13A-45, INSPECTION PROCEDURE 31.)
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
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
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
Basic idle adjustment (Refer to P.13A-79.)
Check trouble symptom.NGClean the throttle valve area. (Refer to P.13A-78.)
Check and adjust the fixed SAS. (Refer to P.13A-79.)

MPI ± Troubleshooting13A-32
INSPECTION PROCEDURE 11
When the engine is cold, it stalls at idling. (Die out)
Probable cause
In such cases as the above, the cause is probably that the air/fuel mixture is inappropriate
when the engine is cold, or that the intake air volume is insufficient.
Malfunction of the ISC servo system

Malfunction of the throttle body

Malfunction of the injector system

Malfunction of the ignition system
Were the battery terminals disconnected?Ye sAfter warming-up, let the engine run at idling for 10 minutes.
No
MUT-II Self-Diag code
Are diagnosis codes displayed?Ye sRefer to P.13A-10, INSPECTION CHART FOR DIAGNOSIS
CODES.
OK
Check the fuel pressure. (Refer to P.13A-81.)
OK
Check the ignition timing.
(Refer to GROUP 11 ± On-vehicle Service.)NGCheck that the distributor is installed properly.
OK
Check the following items.

Check the ignition coil, spark plugs, spark plug cables. (Refer to GROUP 16 ± On-vehicle Service.)

Check the compression pressure. (Refer to GROUP 11 ± On-vehicle Service.)

Check the engine oil viscosity.
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
Check the injector for operation sound.NGCheck the injector system. (Refer to P.13A-19, INSPECTION PRO-
CEDURE FOR DIAGNOSIS CODE 41.)
Ye s
Check the ISC servo for operation sound. (Refer to P.13A-90.)NGCheck the ISC servo system.
(Refer to P.13A-45, INSPECTION PROCEDURE 31.)
No
Is engine-idling stable after the warming-up?NoCheck if the unstable idling (Rough idling, hunting).
(Refer to P.13A-29, INSPECTION PROCEDURE 8.)
No
Does the engine stall right after the accelerator pedal is released?Ye sClean the throttle valve
area. (Refer to P.13A-78.)Check and adjust the
fixed SAS.
(Refer to P.13A-79.)
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
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.)