Mitsubishi Colt Ralliart. Manual — part 690

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI) <4G1>

13B-85

TROUBLE JUDGMENT

Check Conditions

• After engine starts

• Engine coolant temperature is more than 20°C.

• Battery voltage is more than 11 V and is less than

16 V.

Judgement Criterion

• For 4 seconds, oxygen sensor (rear) heater cur-

rent is less than 0.16 A or more than 5.0 A.

PROBABLE CAUSES

• Failed oxygen sensor (rear) heater

• Open/short circuit and damage in oxygen sensor

(rear) heater circuit or loose connector contact

• Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. Connector check: B-53 oxygen sensor
(rear) connector

Q: Is the check result normal?

YES :

Go to Step 2 .

NO :

Repair or replace the connector.

STEP 2. Perform resistance measurement at B-53
oxygen sensor (rear) connector.

• Disconnect connector, and measure at sensor

side.

• Resistance between terminal No. 3 and No. 4.

OK: 5

− 30 Ω (at 20°C)

Q: Is the check result normal?

YES :

Go to Step 3 .

NO :

Replace the oxygen sensor (rear).

AK402019

3

2

1

4

Oxygen sensor (rear)

Connector: B-53

B-53 Harness side connector

AC

B-53

AK402019

3

2

1

4

Oxygen sensor (rear)

Connector: B-53

B-53 Harness side connector

AC

B-53

Main

Index

Group

TOC

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI) <4G1>

13B-86

STEP 3. Perform voltage measurement at B-53
oxygen sensor (rear) connector.

• Disconnect connector, and measure at harness

side.

• Ignition switch: ON

• Voltage between terminal No. 4 and earth.

OK: System voltage

Q: Is the check result normal?

YES :

Go to Step 5 .

NO :

Go to Step 4 .

STEP 4. Connector check: B-106 engine control
relay connector

AK402019

3

2

1

4

Oxygen sensor (rear)

Connector: B-53

B-53 Harness side connector

AC

B-53

3

2

1

4

AK402084

J/B side
connector

B-106

Connector: B-106
J/B (front side)

AC

AK402019

3

2

1

4

Oxygen sensor (rear)

Connector: B-53

B-53 Harness side connector

AC

B-53

Main

Index

Group

TOC

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI) <4G1>

13B-87

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-53 (terminal No. 4)
oxygen sensor (rear) connector and B-106
(terminal No. 4) engine control relay
connector.

• Check power supply line for

open/short circuit.

NO :

Repair or replace the connector.

STEP 5. Perform voltage measurement at A-08
engine-ECU connector.

• Disconnect engine-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. 79 and earth.

OK: System voltage

Q: Is the check result normal?

YES :

Go to Step 8 .

NO :

Go to Step 6 .

STEP 6. Connector check: A-08 engine-ECU
connector

Q: Is the check result normal?

YES :

Go to Step 7 .

NO :

Repair or replace the connector.

AK402725

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127

128

129

72 71

74 73

76 75

R

AI

A-08

Connector:

A-08

A-08 Special tool power plant ECU check
harness

Engine-ECU

Battery

AK402725

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79

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84

92

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132

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134

135

136

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125

126

127

128

129

72 71

74 73

76 75

R

AI

A-08

Connector:

A-08

A-08 Special tool power plant ECU check
harness

Engine-ECU

Battery

Main

Index

Group

TOC

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI) <4G1>

13B-88

STEP 7. Check harness between B-53 (terminal
No. 3) oxygen sensor (rear) connector and A-08
(terminal No. 79) engine-ECU connector.

• Check earthing line for open/short circuit.

Q: Is the check result normal?

YES :

Replace engine-ECU.

NO :

Repair the damaged harness wire.

STEP 8. Connector check: A-08 engine-ECU
connector

Q: Is the check result normal?

YES :

Go to Step 9 .

NO :

Repair or replace the connector.

AK402019

3

2

1

4

Oxygen sensor (rear)

Connector: B-53

B-53 Harness side connector

AC

B-53

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

AI

A-08

Connector:

A-08

A-08 Special tool power plant ECU check
harness

Engine-ECU

Battery

Main

Index

Group

TOC