Mitsubishi Lancer Evolution IX. Manual — part 390

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-35

Code No. P105: Barometric Pressure Sensor System

OPERATION

• A power voltage of 5 V is applied to the baromet-

ric pressure sensor power terminal (terminal No.
1) of the air flow sensor connector from the
engine-ECU (terminal No. 42) and earthed to the
engine-ECU (terminal No. 34) from the air flow
sensor (terminal No. 5).

• The sensor signal is inputted to the engine-ECU

(terminal No. 51) from the barometric pressure
sensor output terminal (terminal No. 2) of the air
flow sensor connector.

FUNCTION

• The barometric pressure sensor converts the bar-

ometric pressure into a voltage signal and inputs
the signal to the engine-ECU.

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

rects the fuel injection amount, etc.

TROUBLE JUDGMENT

Check Condition

• 2 seconds after the ignition switch has been

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

Judgment Criterion

• The sensor output voltage of 4.5 V or more (Baro-

metric pressure above 114 kPa or equivalent) for

2 seconds.

or

• The sensor output voltage 0.2 V or less (Baro-

metric pressure below 53 kPa or equivalent) for 2

seconds.

PROBABLE CAUSES

• Failed barometric pressure sensor

• Open/short circuit in barometric pressure sensor

circuit or loose connector contact

• Failed engine-ECU

7

4 5 6

1 2 3

AK501801

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

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

3132 33

34 35

1

10

5 V

Engine-ECU

42

GR

Y-L

B

51

34

Barometric pressure sensor
(Incorporated in air flow sensor)

1

2

5

Barometric pressure 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

AB

B-105

(MU802552)

C-119

(MU803782)

C-121

(MU803783)

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-36

DIAGNOSIS PROCEDURE

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

• Refer to Data List Reference Table

P.13A-372

.

a. Item No. 25: Barometric pressure sensor

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-105 air flow sensor
connector

Q: Is the check result normal?

YES :

Go to Step 3 .

NO :

Repair or replace the connector.

STEP 3. Perform voltage measurement at B-105
air flow sensor connector.

• Disconnect connector, and measure at harness

side.

• Ignition switch: "ON"

• Voltage between terminal No. 1 and earth.

OK: 4.9

− 5.1 V

Q: Is the check result normal?

YES :

Go to Step 9 .

NO :

Go to Step 4 .

STEP 4. Perform voltage measurement at C-119
engine-ECU connector.

• Measure engine-ECU terminal voltage.

• Ignition switch: "ON"

• Voltage between terminal No. 42 and earth.

OK: 4.9

− 5.1 V

Q: Is the check result normal?

YES :

Go to Step 5 .

NO :

Go to Step 6 .

AK305005

3

4

5

1

2

6

7

AB

Connector : B-105

Harness side
connector

B-105(B)

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>

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-37

STEP 5. Connector check: C-119 engine-ECU
connector

Q: Is the check result normal?

YES :

Check and repair harness between B-105

(terminal No. 1) air flow sensor connector
and C-119 (terminal No. 42) engine-ECU
connector.

• Check power supply line for open

circuit.

NO :

Repair or replace the connector.

STEP 6. Connector check: C-119 engine-ECU
connector

Q: Is the check result normal?

YES :

Go to Step 7 .

NO :

Repair or replace the connector.

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>

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>

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-38

STEP 7. Check harness between B-105 (terminal
No. 1) air flow sensor connector and C-119
(terminal No. 42) engine-ECU connector.

• Check power supply line for short circuit.

Q: Is the check result normal?

YES :

Go to Step 8 .

NO :

Repair the damaged harness wire.

STEP 8. M.U.T.-II/III data list

• Refer to Data List Reference Table

P.13A-372

.

a. Item No. 25: Barometric pressure sensor

Q: Is the check result normal?

YES :

Intermittent malfunction (Refer to GROUP

00

− How to Use

Troubleshooting/Inspection Service Points

P.00-5

).

NO :

Replace the engine-ECU.

STEP 9. Perform resistance measurement at
B-105 air flow sensor connector.

• Disconnect connector, and measure at harness

side.

• Resistance between terminal No. 5 and earth.

OK: 2

Ω or less

Q: Is the check result normal?

YES :

Go to Step 12 .

NO :

Go to Step 10 .

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>

AK305005

3

4

5

1

2

6

7

AB

Connector : B-105

Harness side
connector

B-105(B)