Mitsubishi Colt Ralliart. Manual - part 82

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI) <4A9>

13A-282

OPERATION

• The battery voltage is applied to the engine con-

trol relay (terminal No. 1 and 3).

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

<CVT> (terminal No. 107) makes the power tran-
sistor in the unit be in ON position and makes 
currents go on the engine control relay coil, and 
that makes the relay be in ON position.

• When the engine control relay is in ON position, 

the battery voltage is supplied to the engine-ECU 
<M/T> or engine-CVT-ECU <CVT>, the sensor 
and the actuator from the engine control relay 
(terminal No. 4).

FUNCTION

• When the ignition switch ON signal is input to the 

engine-ECU <M/T> or engine-CVT-ECU <CVT>, 
the engine-ECU <M/T> or engine-CVT-ECU 
<CVT> places the engine control relay in the ON 
position. Accordingly, the battery voltage is sup-
plied to the engine-ECU <M/T> or 
engine-CVT-ECU <CVT>, sensor and actuator.

PROBABLE CAUSES

• Failed battery

• Failed engine control relay

• Open/short/damaged circuit in engine control 

relay circuit or loose connector contact

• Open/short/damaged circuit in ignition switch-IG1 

circuit or loose connector contact

• Open/damaged circuit in engine-ECU <M/T> or 

engine-CVT-ECU <CVT> earth circuit or loose 
connector contact

• Failed engine-ECU <M/T> or engine-CVT-ECU 

<CVT>

DIAGNOSIS PROCEDURE

STEP 1. Check battery voltage.

• Measure battery voltage during cranking.

OK: 8 V or more

Q: Is the check result normal?

YES : 

Go to Step 2 .

NO : 

Check battery (Refer to GROUP 54A 

− 

Battery 

− On-vehicle Service − Battery Test 

P.54A-5

).

STEP 2. Connector check: B-106 engine control 
relay connector

Q: Is the check result normal?

YES : 

Go to Step 3 .

NO : 

Repair or replace the connector.

STEP 3. Check engine control relay.

• Check engine control relay (Refer to 

P.13A-360

).

Q: Is the check result normal?

YES : 

Go to Step 4 .

NO : 

Replace engine control relay.

3

2

1

4

AK402060

B-106
J/B side 
connector

B-106

Connector: B-106
J/B (front side)

AC

Main

Index

Group

TOC

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI) <4A9>

13A-283

STEP 4. Perform voltage measurement at B-106 
engine control relay connector.

• Remove relay, and measure at relay box side.

• Ignition switch: ON

• Voltage between terminal No. 1 and earth, also 

between terminal No. 3 and earth.

OK: System voltage

Q: Is the check result normal?

YES : 

Go to Step 5 .

NO : 

Check intermediate connector B-108, and 

repair if necessary. If intermediate 
connector is normal, check and repair 
harness between B-106 (terminal No. 1 and 
terminal No. 3) engine control relay 
connector and battery.

• Check power supply line for 

open/short circuit.

STEP 5. Connector check: A-08 engine-ECU 
connector or engine-CVT-ECU connector

Q: Is the check result normal?

YES : 

Go to Step 6 .

NO : 

Repair or replace the connector.

3

2

1

4

AK402060

B-106
J/B side 
connector

B-106

Connector: B-106
J/B (front side)

AC

AK402725

77

78

79

80

81

82

83

84

92

93

94

95

96

97

98

99

85

86

87

88

89

90

91

100

101

102

103

104

105

106

115

116

117

118

119

120

121

107

108

109

110

111

112

113

114

130

131

132

133

134

135

136

122

123

124

125

126

127

128

129

72 71

74 73

76 75

R

AG

A-08

Connector: 

A-08

Harness side connector

Battery

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

Main

Index

Group

TOC

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI) <4A9>

13A-284

STEP 6. Perform voltage measurement at A-08 
engine-ECU connector or engine-CVT-ECU 
connector.

• Disconnect engine-ECU connector or 

engine-CVT-ECU connector, and connect Special 
Tool Power Plant ECU Check Harness 
(MB991987), and then measure the voltage on 
the check connector.

• Ignition switch: ON

• Voltage between terminal No. 77 and earth, also 

between terminal No. 92 and earth.

OK: System voltage

Q: Is the check result normal?

YES : 

Check intermediate connector B-112, and 

repair if necessary. If intermediate 
connector is normal, check and repair 
harness between B-106 (terminal No. 2) 
engine control relay connector and A-08 
(terminal No. 107) engine-ECU connector or 
engine-CVT-ECU connector.

• Check signal line for short circuit.

NO : 

Go to Step 7 .

AK402725

77

78

79

80

81

82

83

84

92

93

94

95

96

97

98

99

85

86

87

88

89

90

91

100

101

102

103

104

105

106

115

116

117

118

119

120

121

107

108

109

110

111

112

113

114

130

131

132

133

134

135

136

122

123

124

125

126

127

128

129

72 71

74 73

76 75

R

AH

A-08

Connector: 

A-08

A-08 Special tool power plant ECU check 
harness

Battery

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

3

2

1

4

AK402060

B-106
J/B side 
connector

B-106

Connector: B-106
J/B (front side)

AC

Main

Index

Group

TOC

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI) <4A9>

13A-285

STEP 7. Check harness between B-106 (terminal 
No. 4) engine control relay connector and A-08 
(terminal No. 77 and No. 92) engine-ECU 
connector or engine-CVT-ECU connector.

• Check power supply line for open/short circuit 

and damage.

Q: Is the check result normal?

YES : 

Go to Step 8 .

NO : 

Repair the damaged harness wire.

3

2

1

4

AK402060

B-106
J/B side 
connector

B-106

Connector: B-106
J/B (front side)

AC

AK402725

77

78

79

80

81

82

83

84

92

93

94

95

96

97

98

99

85

86

87

88

89

90

91

100

101

102

103

104

105

106

115

116

117

118

119

120

121

107

108

109

110

111

112

113

114

130

131

132

133

134

135

136

122

123

124

125

126

127

128

129

72 71

74 73

76 75

R

AG

A-08

Connector: 

A-08

Harness side connector

Battery

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

Main

Index

Group

TOC