Mitsubishi Lancer Evolution IX. Manual — part 394

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-51

STEP 15. Check harness between B-105 (terminal
No. 6) air flow sensor connector and C-119
(terminal No. 62) engine-ECU connector.

• Check output line for damage.

Q: Is the check result normal?

YES :

Go to Step 16 .

NO :

Repair the damaged harness wire.

STEP 16. Connector check: C-121 engine-ECU
connector

Q: Is the check result normal?

YES :

Check and repair harness between B-105

(terminal No. 5) air flow sensor connector
and C-121 (terminal No. 34) engine-ECU
connector.

• Check earthing line for damage.

NO :

Repair or replace the connector.

AK305005

3

4

5

1

2

6

7

AB

Connector : B-105

Harness side
connector

B-105(B)

AK501994

65

43
50

42
49

41
48
60

61

64

46

47

58

59

67

68

45

56
66

52 51

44

53

62

54

63

57

55

AB

Connector: C-119

C-119 (GR)

C-119 (GR)

Harness side connector

<L. H. drive vehicles>

<R. H. drive vehicles>

AK501995

2

3

4

5

6

7

8

9

11

12

13

14

15

16

17

18

19

20

30

21

22

23

24

25

26

27

28

29

31

32

33

34

35

1

10

AB

Connector: C-121

C-121 (GR)

C-121 (GR)

Harness side connector

<L. H. drive vehicles>

<R. H. drive vehicles>

AK305005

3

4

5

1

2

6

7

AB

Connector : B-105

Harness side
connector

B-105(B)

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-52

Code No. P0115: Engine Coolant Temperature Sensor System

OPERATION

• A power voltage of 5 V is applied to the engine

coolant temperature sensor output terminal (ter-
minal No. 1) from the engine-ECU (terminal No.
44).

• The power voltage is earthed to the engine-ECU

(terminal No. 49) from the engine coolant temper-
ature sensor (terminal No. 2).

FUNCTION

• The engine coolant temperature sensor converts

the engine coolant temperature into a voltage sig-
nal, and inputs the voltage to the engine-ECU.

• In response to the signal, the engine-ECU con-

trols the fuel infection amount and the fast idle
speed when the engine is cold state.

• The engine coolant temperature sensor is a kind

of resistor, which has characteristics to reduce its
resistance as the engine coolant temperature
rises. Therefore, the sensor output voltage varies
with the engine coolant temperature, and
becomes lower as the engine coolant tempera-
ture rises.

TROUBLE JUDGMENT

Check Condition

• 2 seconds later after the ignition switch has been

in "ON" position or the engine has started up.

Judgment Criteria

• The sensor output voltage of 4.6 V or more

(engine coolant temperature of

−45°C or equiva-

lent) for 2 seconds,

or

• The sensor output voltage of 0.1 V or less

(engine coolant temperature of 140

°C or more, or

equivalent) for 2 seconds.

1 2

AK501803

65

43
50

42
49

41
48
60 61

64

46 47
58 59
67 68

45

56
66

52

51

44

53

62

54

63

57

55

5 V

49

44

B

Y-W

Engine-ECU

Engine coolant temperature sensor

B-107

(MU802406)

2

1

Engine coolant temperature sensor circuit

Wire colour code
B: Black LG: Light green G: Green L: Blue W: White Y: Yellow SB: Sky blue BR: Brown O: Orange GR: Gray
R: Red P: Pink V: Violet PU: Purple

C-119

(MU803782)

AB

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-53

Check Conditions

• Ignition switch: "ON"

• Engine speed of 50 r/min. or more

Judging Conditions

• The sensor output voltage rises 1.6 V or more

(engine coolant temperature below 40

°C or

equivalent) from 1.6 V or less (engine coolant
temperature above 40

°C or equivalent).

• Thereafter, the sensor output voltage is 1.6 V or

more for 5 minutes.

PROBABLE CAUSES

• Failed engine coolant temperature sensor

• Open/short circuit in engine coolant temperature

sensor circuit or loose connector contact

• Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-II/III data list

• Item No. 21: Engine coolant temperature sensor

OK:

Engine cold state: At ambient temperature or

equivalent.

Engine hot state: At 80

− 120°C

Q: Is the check result normal?

YES :

Intermittent malfunction (Refer to GROUP

00

− How to Use

Troubleshooting/Inspection Service Points

P.00-5

).

NO :

Go to Step 2 .

STEP 2. Connector check: B-107 engine coolant
temperature sensor connector

Q: Is the check result normal?

YES :

Go to Step 3 .

NO :

Repair or replace the connector.

STEP 3. Perform resistance measurement at
B-107 engine coolant temperature sensor
connector.

• Disconnect connector, and measure at sensor

side.

• Resistance between terminal No. 1 and No. 2.

OK:

Engine coolant temperature at

−20°C: 14 − 17

k

Ω

Engine coolant temperature at 0

°C: 5.1 − 6.5

k

Ω

Engine coolant temperature at 20

°C: 2.1 − 2.7

k

Ω

Engine coolant temperature at 40

°C: 0.9 − 1.3

k

Ω

Engine coolant temperature at 60

°C: 0.48 −

0.68 k

Ω

Engine coolant temperature at 80

°C: 0.26 −

0.36 k

Ω

Q: Is the check result normal?

YES :

Go to Step 4 .

NO :

Replace the engine coolant temperature
sensor.

AK305008

1

2

AB

Connector : B-107

Harness side
connector

B-107(B)

AK305008

1

2

AB

Connector : B-107

Harness side
connector

B-107(B)

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-54

STEP 4. Perform voltage measurement at B-107
engine coolant temperature sensor connector.

• Disconnect connector, and measure at harness

side.

• Ignition switch: "ON"

• Voltage between terminal No. 1 and earth.

OK: 4.5

− 4.9 V

Q: Is the check result normal?

YES :

Go to Step 10 .

NO :

Go to Step 5 .

STEP 5. Perform voltage measurement at C-119
engine-ECU connector.

• Measure engine-ECU terminal voltage.

• Disconnect B-107 engine coolant temperature

sensor.

• Ignition switch: "ON"

• Voltage between terminal No. 44 and earth.

OK: 4.5

− 4.9 V

Q: Is the check result normal?

YES :

Go to Step 6 .

NO :

Go to Step 7 .

AK305008

1

2

AB

Connector : B-107

Harness side
connector

B-107(B)

AK501994

65

43
50

42
49

41
48
60

61

64

46

47

58

59

67

68

45

56
66

52 51

44

53

62

54

63

57

55

AB

Connector: C-119

C-119 (GR)

C-119 (GR)

Harness side connector

<L. H. drive vehicles>

<R. H. drive vehicles>

AK305008

1

2

AB

Connector : B-107

Harness side
connector

B-107(B)