Mitsubishi Montero Sport (2004+). Manual - part 348

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-805

.

CIRCUIT OPERATION

• Battery positive voltage is applied to the MFI 

relay (terminals No. 3, No. 4).

• When the ignition switch is turned to the "ON" 

position, the battery positive voltage is applied to 
the PCM (terminal No. 98).

• When the battery positive voltage is applied, the 

PCM turns the power transistor in the PCM "ON" 
and grounds the MFI relay coil. With this, the MFI 
relay turns "ON" and the battery positive voltage 
is supplied to the PCM (terminals No. 41, No. 47) 
from the MFI relay (terminal No. 1).

• Battery positive voltage is constantly supplied to 

the PCM (terminal No. 66) as the backup power.

• The PCM (terminals No. 42, No. 48) is grounded 

to the vehicle body.

.

TROUBLESHOOTING HINTS (The most likely 
causes for this code to be set are: ) 

• Malfunction of the ignition switch.

• Malfunction of the MFI relay.

• Improper connector contact, open circuit or 

short-circuited harness wire.

• Disconnected PCM ground wire.

• Malfunction of the PCM.

AK201000

MFI RELAY

CONNECTOR: C-59

AB

C-59

AK200040AB

CONNECTOR: D-15

D-15(B)

AK103911AB

CONNECTOR: C-14

C-14

AK103738AE

CONNECTORS: C-90, C-91

PCM

C-91(GR)

C-90(GR)

AK200035AB

CONNECTOR: D-08

D-08

JUNCTION BLOCK
(REAR SIDE)

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-806

DIAGNOSIS

STEP 1. Check harness connector C-59 at MFI relay for 
damage.
Q: Is the harness connector in good condition?

YES :  Go to Step 2.
NO :  Repair or replace it. Refer to GROUP 00E, Harness 

Connector Inspection 

P.00E-2

. Then confirm that the 

malfunction symptom is eliminated.

STEP 2. Check the MFI relay
(1) Remove the MFI relay.

(2) Check for continuity between the MFI relay terminal No. 2 

and No. 4.

• There should be continuity (approximately 70 ohms)

(3) Use jumper wires to connect MFI relay terminal No. 4 to the 

positive battery terminal and terminal No. 2 to the negative 
battery terminal.

(4) Check for continuity between the MFI relay terminal No. 1 

and No. 3 while connecting and disconnecting the jumper 
wire at the negative battery terminal.

• Should be less than 2 ohms. (Negative battery terminal 

connected)

• Should be open loop. (Negative battery terminal discon-

nected)

(5)  Install the MFI relay.
Q: Is the measured voltage within the specified range?

YES : Go to Step 3.
NO :  Replace the MFI relay. Then confirm that the 

malfunction symptom is eliminated.

AK200023

2 1

3

4

CONNECTOR: C-59

AB

C-59

HARNESS 
CONNECTOR:
COMPONENT 
SIDE

AK200023

2 1

3

4

CONNECTOR: C-59

AB

C-59

HARNESS 
CONNECTOR:
COMPONENT 
SIDE

AK200198

1

2

3

4

MFI RELAY SIDE
CONNECTOR

AB

AK200199

1

2

3

4

MFI RELAY SIDE
CONNECTOR

AB

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-807

STEP 3. Measure the power supply voltage at MFI relay 
harness side connector C-59.
(1) Disconnect the connector C-59 and measure at the harness 

side.

(2) Measure the voltage between terminals No. 3, No. 4 and 

ground.

• Voltage should be battery positive voltage.

Q: Is battery positive voltage (approximately 12 volts) 

present?
YES : Go to Step 4.
NO :  Repair harness wire between fusible link (12) and MFI 

relay connector C-59 (terminals No. 3, No. 4). Then 
confirm that the malfunction symptom is eliminated.

STEP 4. Check harness connector C-91 at PCM for 
damage.
Q: Is the harness connector in good condition?

YES : Go to Step 5.
NO :  Repair or replace it. Refer to GROUP 00E, Harness 

Connector Inspection 

P.00E-2

. Then confirm that the 

malfunction symptom is eliminated.

AK200023

2 1

3

4

CONNECTOR: C-59

AB

C-59

HARNESS 
CONNECTOR:
COMPONENT 
SIDE

2 1

3

4

AK200197

C-59 HARNESS 
CONNECTOR: 
COMPONENT SIDE

AK200197AD

AK104028

98

78

71

88

89

76

77

72
79
91

73
80

74

75

81
92

82

83

93

84

85

94

86

87

95

96

90

97

AB

CONNECTOR: C-91

C-91(GR)

HARNESS CONNECTOR:
COMPONENT SIDE

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-808

STEP 5. Measure the ignition switch-IG signal voltage at 
PCM harness side connector C-91.
(1) Disconnect the connector C-91 and measure at the harness 

side.

(2) Turn the ignition switch to the "ON" position.

(3) Measure the voltage between terminal No. 98 and ground.

• Voltage should be battery positive voltage.

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is battery positive voltage (approximately 12 volts) 

present?
YES : Go to Step 6.
NO :  Check harness connector D-08 at intermediate 

connector for damage, and repair or replace as 
required. Refer to, GROUP 00E, Harness Connector 
Inspection 

P.00E-2

. If intermediate connectors D-08 

is in good condition, repair harness wire between 
ignition switch connector D-15 (terminal No. 2) and 
PCM connector C-91 (terminal No. 98). Then confirm 
that the malfunction symptom is eliminated.

AK104028

98

78

71

88

89

76

77

72
79
91

73
80

74

75

81
92

82

83

93

84

85

94

86

87

95

96

90

97

AB

CONNECTOR: C-91

C-91(GR)

HARNESS CONNECTOR:
COMPONENT SIDE

AKX01435

71

72

73

74

78

79

80

81

90

91

82

83

93

94

92

84

85

86

95

96

87

88

89

75

76

77

97

98

C-91 HARNESS 
CONNECTOR: 
COMPONENT SIDE

AP