Mitsubishi Outlander (2003+). Manual - part 77

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MFI)

13A-171

Code No. P1603: Battery Backup Line System

OPERATION

œ

Power is directly supplied to the engine-ECU (ter-
minal No. 80) from the battery.

FUNCTION

œ

The engine-ECU is check the open circuit of bat-
tery backup line.

TROUBLE JUDGMENT

Check Condition

œ

Ignition switch: ON 

Judgment Criterion

œ

The battery backup line voltage 6 V or less.

PROBABLE CAUSE

œ

Open/short circuit in battery backup line circuit or 
loose connector contact

œ

Failed engine-ECU 

AK300297

82

78

81

80

89 90 9192

79

87

71

74

73

72

76

75

77

85

88

83 84

86

9

20A

AB

Battey

W

W-B

W-B

80

Engine-ECU

A-14
5

Relay box

C-137

Battery backup 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

Battery 
backup

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MFI)

13A-172

DIAGNOSIS PROCEDURE

STEP 1 MUT-II self-diag code

œ

Temporarily place the ignition switch in "LOCK" 
(OFF) position, and 10 seconds after that, place it 
in "ON" position again.

Q: Is the diagnosis code P1603 set?

YES : 

Go to Step 2 .

NO : 

Intermittent malfunction (Refer to GROUP 
00 

-

 How to use Troubleshooting/Inspection 

Service Points 

3

00



).

STEP 2. Measure voltage at C-137 engine-ECU 
connector.

œ

Disconnect connector, and measure at harness 
side.

œ

Ignition switch: ON

œ

Voltage between terminal No. 80 and earth.

OK: System voltage

Q: Is the check result normal?

YES : 

Go to Step 3 .

NO : 

Check intermediate connector A-14, and 

repair if necessary. If intermediate 
connector is normal, check and repair 
harness between battery and C-137 
(terminal No. 80) engine-ECU connector.

œ

Check power supply line for 
open/short circuit.

STEP 3. Connector check: C-137 engine-ECU 
connector

Q: Is the check result normal?

YES : 

Go to Step 4 .

NO : 

Repair.

STEP 4. Check the trouble symptoms.

Q: Does trouble symptom persist?

YES : 

Replace engine-ECU.

NO : 

Intermittent malfunction (Refer to GROUP 
00 

-

 How to Use 

Troubleshooting/Inspection Service 
Points

3

00



).

AK300254

82

78

8180

89

90

91

92

79

87

71

74 73 72

76 75

77

85

88

83

84

86

AB

CONNECTOR: C-137

C-137

Harness side connector

AK300254

82

78

8180

89

90

91

92

79

87

71

74 73 72

76 75

77

85

88

83

84

86

AB

CONNECTOR: C-137

C-137

Harness side connector

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MFI)

13A-173

Code No. P1610: Immobilizer System

OPERATION

œ

The signals are sent and received between 
engine-ECU (terminal No. 51) and immobilizer-
ECU (terminal No. 7).

FUNCTION

œ

Engine-ECU sends or receives the control sig-
nals to or from immobilizer-ECU to certify the 
ignition key.

NOTE: 

.

œ

If the registered ignition keys are close each 
other when starting the engine, radio interfer-
ence may cause this code to be displayed.

œ

This code may be displayed when registering 
the key encrypted code.

TROUBLE JUDGMENT

Check Condition

œ

Ignition switch: ON

Judgment Criterion

œ

Improper communication problems between the 
engine-ECU and the immobilizer-ECU are 
detected.

PROBABLE CAUSE

œ

Open/short circuit in immobilizer system circuit or 
loose connector contact

œ

Failed immobilizer-ECU

œ

Failed engine-ECU

AK300298

57 58

60 61

53

52

51

55

54

56

59

62

1

2

3 4 5 6 7

3

51

7

11

C-304

(MU801547)

C-104

Engine-ECU

Immobilizer-ECU circuit

Immobilizer-ECU

AB

V

V

C-136

C-304-1

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

Signal 
transmission 
circuit

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MFI)

13A-174

DIAGNOSIS PROCEDURE

STEP 1. Connector check: C-304 immobilizer-
ECU connector and C-136 engine-ECU connector

Q: Is the check result normal? 

YES : 

Go to Step 2 .

NO : 

Repair.

STEP 2. Check harness between C-304 (terminal 
No. 3) immobilizer-ECU connector and C-136 
(terminal No. 51) engine-ECU connector.

NOTE: Before checking harness, check intermediate 
connector C-104, and repair if necessary.

œ

Check output line for open/short circuit and dam-
age.

Q: Is the check result normal? 

YES : 

Go to Step 3 .

NO : 

Repair.

STEP 3. Check the trouble symptoms.

Q: Is the check result normal? 

YES : 

Go to Step 4 .

NO : 

Intermittent malfunction (Refer to GROUP 
00 

-

 How to Use 

Troubleshooting/Inspection Service Points 

3

00



).

STEP 4. After replacing the immobilizer-ECU, re-
check the trouble symptoms.

Q: Is the check result normal? 

YES : 

Replace engine-ECU.

NO : 

Check end.

AK203418

2

7 6 5 4 3

1

AC

Connector: C-304

C-304

Harness side
connector

AK300268

58

60

61

53 52 51

55 54

56

59

62

57

AB

CONNECTOR: C-136

C-136

Harness side connector

AK203418

2

7 6 5 4 3

1

AC

Connector: C-304

C-304

Harness side
connector

AK300268

58

60

61

53 52 51

55 54

56

59

62

57

AB

CONNECTOR: C-136

C-136

Harness side connector