Mitsubishi Colt Ralliart. Manual - part 56

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI) <4A9>

13A-178

• When the throttle valve control servo relay turns 

ON, battery voltage is supplied by the throttle 
valve control servo relay (terminal No. 4) to the 
engine-ECU <M/T> or engine-CVT-ECU <CVT> 
(terminal No. 78).

FUNCTION

• When the ignition switch ON signal is input into 

the engine-ECU <M/T> or engine-CVT-ECU 
<CVT>, the engine-ECU <M/T> or 
engine-CVT-ECU <CVT> turns ON the Throttle 
valve control servo.

TROUBLE JUDGMENT

Check Conditions

• After engine starts <M/T>

• Ignition switch is in "ON" position <CVT>.

Judgement Criteria

• Throttle valve control servo supply voltage is 6.0 

V or less <M/T>.

• Battery voltage is 8.3 V or more <CVT>.

• The power line voltage of the electronic controlled 

throttle system is 6.0 V or less for 0.35 second 
<CVT>.

PROBABLE CAUSES

• Failed throttle valve return spring

• Open/short circuit in throttle valve control servo 

circuit or loose connector contact.

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

<CVT>

DIAGNOSIS

STEP 1. Connector check: B-121 throttle valve 
control servo relay connector

Q: Is the check result normal?

YES : 

Go to Step 2 .

NO : 

Repair or replace the connector.

STEP 2. Check throttle valve control servo relay 
itself.

• Check throttle valve control servo relay (Refer to 

P.13A-361

).

Q: Is the check result normal?

YES : 

Go to Step 3 .

NO : 

Replace the throttle valve control servo 
relay.

STEP 3. Perform voltage measurement at B-121 
throttle valve control servo relay connector.

• Remove relay, and measure at relay box side.

• Voltage between terminal No. 3 and earth.

OK: System voltage

Q: Is the check result normal?

YES : 

Go to Step 4 .

NO : 

Check intermediate connector B-108, and 

repair if necessary. if intermediate connector 
is normal, Check and repair harness 
between B-121 (terminal No. 3) throttle 
valve control servo relay connector and 
battery.

• Check power supply line for 

open/short circuit.

AK402030

3

2

1

4

Connector: B-121

B-121

AC

B-121 
Relay box side 
connector

AK402030

3

2

1

4

Connector: B-121

B-121

AC

B-121 
Relay box side 
connector

Main

Index

Group

TOC

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI) <4A9>

13A-179

STEP 4. Perform voltage measurement at B-121 
throttle valve control servo relay connector.

• Remove relay, and measure at relay box side.

• Ignition switch: ON

• Voltage between terminal No. 1 and earth.

OK: System voltage

Q: Is the check result normal?

YES : 

Go to Step 6 .

NO : 

Go to Step 5 .

STEP 5. Connector check: B-106 engine control 
relay connector

Q: Is the check result normal?

YES : 

Check and repair harness between B-106 

(terminal No. 4) engine control relay 
connector and B-121 (terminal No. 1) 
throttle valve control servo relay connector.

• Check power supply line for 

open/short circuit.

NO : 

Repair or replace the connector.

AK402030

3

2

1

4

Connector: B-121

B-121

AC

B-121 
Relay box side 
connector

3

2

1

4

AK402060

B-106
J/B side 
connector

B-106

Connector: B-106
J/B (front side)

AC

AK402030

3

2

1

4

Connector: B-121

B-121

AC

B-121 
Relay box side 
connector

Main

Index

Group

TOC

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI) <4A9>

13A-180

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

• Disconnect connector, and measure at harness 

side.

• Ignition switch: ON

• Voltage between terminal No. 123 and earth.

OK: System voltage

Q: Is the check result normal?

YES : 

Go to Step 7 .

NO : 

Check intermediate connector B-110, and 

repair if necessary. If intermediate 
connector is normal, check and repair 
harness between B-121 (terminal No. 2) 
throttle valve control servo relay connector 
and A-08 (terminal No. 123) engine-ECU 
connector or engine-CVT-ECU connector.

• Check earthing line for open/short 

circuit.

STEP 7. Perform voltage measurement at A-08 
engine-ECU connector or engine-CVT-ECU 
connector.

• Disconnect connector, and measure at harness 

side.

• Ignition switch: ON

• Voltage between terminal No. 78 and earth.

OK: System voltage

Q: Is the check result normal?

YES : 

Go to Step 10 .

NO : 

Go to Step 8 .

AK402725

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R

AG

A-08

Connector: 

A-08

Harness side connector

Battery

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

AK402030

3

2

1

4

Connector: B-121

B-121

AC

B-121 
Relay box side 
connector

AK402725

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123

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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-181

STEP 8. Check harness between B-121 (terminal 
No. 4) throttle valve control servo relay 
connector and A-08 (terminal No. 78) engine-ECU 
connector or engine-CVT-ECU connector.

NOTE: Before checking harness, check intermediate 
connector B-112, and repair if necessary.

• Check power supply line for open/short circuit.

Q: Is the check result normal?

YES : 

Go to Step 9 .

NO : 

Repair the damaged harness wire.

STEP 9. Connector check: A-08 engine-ECU 
connector or engine-CVT-ECU connector.

• Check output line for damage.

Q: Is the check result normal?

YES : 

Replace the engine-ECU <M/T> or 

engine-CVT-ECU <CVT>.

• Check earthing line for open/short 

circuit.

NO : 

Repair or replace the connector.

AK402030

3

2

1

4

Connector: B-121

B-121

AC

B-121 
Relay box side 
connector

AK402725

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109

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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>

AK402725

77

78

79

80

81

82

83

84

92

93

94

95

96

97

98

99

85

86

87

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101

102

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106

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120

121

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112

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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