Mitsubishi Space Star. Manual - part 57

MPI  – 

Troubleshooting

13B-15

OK

Check the trouble symptoms.

NG

Replace the engine-ECU.

OK

Check the harness wire between
the engine coolant temperature
sensor and the engine-ECU, and
repair if necessary.

OK

Check the following connectors:
B-31

NG

Repair

OK

Measure at engine coolant
temperature sensor connector A-76.



Use test harness (MB991658) to
connect the connector, and
measure at the pick-up harness.



Ignition switch: ON



Voltage between terminal 1 and
earth
OK: At 0



C of engine coolant

temperature: 3.2 – 3.8 V
At 20



C of engine coolant

temperature: 2.3 – 2.9 V
At 40



C of engine coolant

temperature: 1.3 – 1.9 V
At 80



C of engine coolant

temperature: 0.3 – 0.9 V

NG

Check the engine coolant
temperature sensor. 
(Refer to P.13B-71*.)

NG

Repair

From the previous page

NOTE:
*:

Refer to the ’99 SPACE STAR Workshop Manual (Pub. No. CMXE99E1)

MPI  – 

Troubleshooting

13B-16

Code No. 0120 Throttle position sensor system

Probable cause

Range of Check



Ignition switch: ON



Excluding 2 seconds after the ignition switch is turned to ON or immediately
after the engine starts.

Set Conditions



Engine speed is 1,000 r/min or less, and intake air pressure is 48kPa or
less, TPS output voltage is 4.6 V or more for 2 seconds.

or



The sensor output voltage is 0.2 V or less for 2 seconds.



Malfunction of throttle position sensor



Open or short circuit in the throttle position
sensor circuit or loose connector contact



Malfunction of the engine-ECU

OK

Check the trouble symptoms.

NG

Replace the engine-ECU.

OK

To the next page

OK

Check the harness wire between
the throttle position sensor and the
engine-ECU.

NG

Repair

(2) NG

Check the following connector:
B-31

NG

Repair

OK

Check the trouble symptoms.

NG

Replace the engine-ECU.

OK

Check the harness wire between
the throttle position sensor and the
engine-ECU.

NG

Repair

NG

Check the following connector:
B-31

NG

Repair

OK

Check the harness wire between
the throttle position sensor and the
engine-ECU, and repair if necessary.

NG

Repair

OK

Check the following connector:
B-31

(1) NG

Measure at engine-ECU connector
B-31.



Measure the voltage at the
engine-ECU connector terminal.



Ignition switch: ON



The voltage between terminal 81
and earth
OK: 4.8  – 5.2 V

OK

Measure at throttle position sensor
connector A-66.



Disconnect the connector and
measure at the harness side.

(1) The voltage between terminal 1

and earth
(Ignition switch: ON)
OK: 4.8  – 5.2 V

(2) Resistance between terminal 4

and earth
OK: 2 

Ω

 or less

OK

Check the following connector:
A-66

NG

Repair

NG

Check throttle position sensor. 
(Refer to P.13B-72*.)

NG

Replace

MUT-

II

 Data list

14 Throttle position sensor

OK: Refer to P.13B-65, DATA

LIST REFERENCE TABLE.

OK

Intermittent malfunction 
(Refer to GROUP 00 – Points to
Note for Intermittent Malfunctions.)

NOTE:
*:

Refer to the ’99 SPACE STAR Workshop Manual (Pub. No. CMXE99E1)

MPI  – 

Troubleshooting

13B-17

NG

Replace the engine-ECU.

OK

Check the trouble symptoms.

OK

Check the following connector:
B-31

NG

Repair

NG

Check the following connector:
B-31

NG

Repair

OK

Measure at engine-ECU connector
B-31.



Measure the voltage at the
engine-ECU terminal.



Ignition switch: ON



The voltage between terminal 84
and earth
OK: Accelerator pedal fully re-

leased: 0.3 – 1.0 V 
Accelerator pedal fully de-
pressed: 4.5 – 5.5 V

OK

Check the harness wire between
throttle position sensor and the
engine-ECU, and repair if necessary.

OK

Measure at throttle position sensor
connector A-66.



Use test harness (MB991536) to
connect the connector, and
measure at the pick-up harness.



Ignition switch: ON

(1) The voltage between terminal 1

and earth
OK: 4.8  – 5.2 V

(2) The voltage between terminal 4

and earth
OK: 0.5 V or less

(3) The voltage between terminal 2

and earth
OK: Accelerator pedal fully re-

leased: 0.3 – 1.0 V 
Accelerator pedal fully de-
pressed: 4.5 – 5.5 V

(1), (2) NG

NG

Repair

Check the following connector:
B-31

NG

Repair

OK

Check the harness wire between
throttle position sensor and the
engine-ECU.

From the previous page

(3) NG

Adjust the throttle position sensor.
(Refer to P.13B-65*.)

OK

Check the harness wire between
throttle position sensor and the
engine-ECU, and repair if necessary.

Check the following connector:
B-31

NOTE:
*:

Refer to the ’99 SPACE STAR Workshop Manual (Pub. No. CMXE99E1)

MPI  – 

Troubleshooting

13B-18

Code No. P0125 Feedback system

Probable cause

Range of Check



The engine coolant temperature is approx. 80



C or more.



During stoichiometric feedback control



The vehicle is not being decelerated.

Set Conditions



Oxygen sensor (front) output voltage has been higher or lower than 0.5 V
for at least thirty seconds.



Malfunction of oxygen sensor (front)



Open or short circuit in the oxygen sensor (front)
circuit or loose connector contact



Malfunction of engine-ECU

NG

Replace the engine-ECU.

OK

Check the trouble symptoms.

OK

Transient malfunction
(Refer to GROUP 00 – Points to
Note for Intermittent Malfunctions.)

OK

Check the following connector:
B-31

Repair

NG

OK

Check the harness wire between
the oxygen sensor (front) and the
engine-ECU, and repair if necessary.

NG

Check the following connector:
B-31

NG

Repair

OK

Measure at engine-ECU connector
B-31.



Measure the voltage at the
engine-ECU terminal.



Engine: 2,500 r/min (after
warming up)



Voltage between terminal 76 and
earth
OK: 0 V and 0.8 V alternate.

OK

Check the harness wire between
the oxygen sensor (front) and the
engine-ECU, and repair if necessary.

OK

NG

Repair

Check the following connector:
B-31

OK

Check the harness wire between
the oxygen sensor (front) and the
engine-ECU, and repair if necessary.

NG

Replace the engine-ECU.

OK

Check the trouble symptoms.

OK

Check the harness wire between
the oxygen sensor (front) and the
engine-ECU.

NG

Repair

Repair

OK

Measure at oxygen sensor (front)
connector A-55.



Disconnect the connector and
measure at the harness side.



Resistance between terminal 2
and earth
OK: 2 

Ω

 or less

NG

Check the following connectors:
B-31

NG

Check the following connector:
A-55

NG

Repair

(2) NG

Check the oxygen sensor (front). 
(Refer to P.13B-80.)

NG

Replace

Repair

OK

Measure at oxygen sensor (front)
connector A-55.



Use the test harness
(MD998464) to connect the
connector, and measure at the
pick-up harness side.



Engine: 2,500 r/min (after
warming up)

(1) Voltage between terminal 2 and

earth
OK: 0.5 V or less

(2) Voltage between terminal 4 and

earth
OK: 0 V and 0.8 V alternate.

(1) NG

Check the following connector:
B-31

NG