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

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Index

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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

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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

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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.

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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

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129

72 71

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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

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79

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92

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103

104

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121

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109

110

111

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113

114

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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