Mitsubishi Grandis. Manual — part 693

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-23

NOTE:

.

•

Do not replace the engine-ECU <M/T> or engine-A/T-ECU <A/T> until a through terminal check reveals
there are no short/open circuit.

•

Check that the engine-ECU <M/T> or engine-A/T-ECU <A/T> earth circuit is normal before checking for
the cause of the problem.

•

After the engine-ECU <M/T> or engine-A/T-ECU <A/T> has detected a malfunction, a diagnosis code is
recorded the next time the engine is started and the same malfunction is re-detected. However, for items
marked with "*", the diagnosis code is recorded on the first detection of the malfunction.

P2173*

Abnormal intake air amount

P.13A-274

U1073

Bus off

P.13A-274

U1102

ABS-ECU time-out

P.13A-275

U1108

Combination meter time-out

P.13A-276

U1110

A/C-ECU time-out

P.13A-278

Code No.

Diagnosis item

Reference page

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-24

INSPECTION PROCEDURE FOR
DIAGNOSIS CODES

Code No. P0100: Air Flow Sensor System

1

2

3

4

1

2

3 4

AK305548

61
656667686970 717273
74757677787980 8182
8384

858687

8889

62

6364

9192

939495

96979899

100

105

113114

115116117

118119120

106

107108109

110111112

101102103

104

W-G

W-G

BR

BR

W-G

R-W

R-W

B-15X

Engine
control
relay

Battery

Air flow
sensor

Engine-ECU <M/T> or
engine-A/T-ECU <A/T>

63

3

96

33

30

2

4

3

4

1

2

Air flow sensor circuit

C-112

(MU803804)

C-116

B-106

AB

J/C (4)

5

11

C-116

J/C (4)

C-113

(MU803805)

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

5V

To engine-ECU <M/T> or
engine-A/T-ECU <A/T>

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-25

OPERATION

• Power is supplied by the engine control relay

(terminal No. 1) to the air flow sensor (terminal
No. 2), and the air flow sensor (terminal No. 4) is
grounded through the engine-ECU <M/T> or
engine-A/T-ECU <A/T> (terminal No. 96).

• The air flow sensor (terminal No. 3) outputs a

sensor signal, which is input into the engine-ECU
<M/T> or engine-A/T-ECU <A/T> (terminal No.
63).

FUNCTION

• The air flow sensor outputs amperage that varies

in accordance with the intake air volume.

• The engine-ECU <M/T> or engine-A/T-ECU

<A/T> uses the amperage output by the air flow
sensor and the engine speed signal in order to
determine the basic injection duration of the
injector.

TROUBLE JUDGMENT

Check Condition

• After 3 seconds have passed since the ignition

switch was turned to ON position.

Judgment Criteria

• Air flow sensor output voltage has continued to

be 0.2 V or lower for 2 seconds.

Or

• Air flow sensor output voltage has continued to

be 4.9 V or higher for 2 seconds.

PROBABLE CAUSE

• Failed air flow sensor

• Open/short circuit in air flow sensor circuit or

loose connector contact

• Failed engine-ECU <M/T>

• Failed engine-A/T-ECU <A/T>

DIAGNOSIS PROCEDURE

STEP 1. MUT-III data list

• Refer to Data List Reference Table

P.13A-363

.

a. Item 12: Air flow 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-106 air flow sensor
connector

Q: Is the check result normal?

YES :

Go to Step 3 .

NO :

Repair or replace.

STEP 3. Perform voltage measurement at B-106
air flow sensor connector.

• Disconnect connector, and measure at harness

side.

• Ignition switch: ON

• Voltage between terminal No. 2 and earth.

OK: System voltage

Q: Is the check result normal?

YES :

Go to Step 5 .

NO :

Go to Step 4 .

AK300969

2

1

3

4

Harness side connector

AC

Connector: B-106

B-106 (GR)

AK300969

2

1

3

4

Harness side connector

AC

Connector: B-106

B-106 (GR)

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-26

STEP 4. Connector check: B-15X engine control
relay connector

Q: Is the check result normal?

YES :

Check intermediate connector C-116, and

repair if necessary. If intermediate
connector is normal, check and repair
harness between B-106 (terminal No. 2) air
flow sensor connector and B-15X (terminal
No. 1) engine control relay connector.

• Check power supply line for

open/short circuit.

NO :

Repair or replace.

STEP 5. Check resistance measurement at B-106
air flow sensor connector.

• Disconnect and measure at harness side.

• Resistance between terminal No. 4 and earth.

OK: 2

Ω or less

Q: Is the check result normal?

YES :

Go to Step 9 .

NO :

Go to Step 6 .

STEP 6. Connector check: C-113 engine-ECU
<M/T> connector or engine-A/T-ECU <A/T>
connector

Q: Is the check result normal?

YES :

Go to Step 7 .

NO :

Repair or replace.

AK300967

2

1

3

4

AC

Harness side
connector

B-15X

Connector: B-15X

Relay box’s
triangle marks

AK300969

2

1

3

4

Harness side connector

AC

Connector: B-106

B-106 (GR)

AK300969

2

1

3

4

Harness side connector

AC

Connector: B-106

B-106 (GR)

AK305616AB

Connector: C-113

<L.H. drive vehicles>

<R.H. drive vehicles>

C-113 (GR)

C-113 (GR)

91

92

93

94

95

96

97

98

99

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

116

117

118

119

120

Harness side connector