Mitsubishi Colt Ralliart. Manual - part 89

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI) <4A9>

13A-310

Inspection Procedure 26: A/C compressor relay system

OPERATION

• The battery voltage is applied to the A/C com-

pressor relay (terminal No. 1 and No. 3).

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

<CVT> (terminal No. 81

*1

 or No. 110

*2

) makes 

the power transistor in the unit be in ON position 
and makes currents go on the A/C compressor 

relay coil, and that makes the relay be in ON 
position.

• When the A/C compressor is in ON position, the 

battery voltage is supplied to the A/C compressor 
(terminal No. 4) from the A/C compressor relay 
assembly (terminal No. 1).

1

AK402705

3

1

2

4

R

92 93 94 95969798

77 78 79 808182838485868788899091

99

100

107 108 109 110 111112113114115116117118119120121
122 123 124 125126127128129130131132133134135136

101102103104105106

71 72

73 74

75 76

24

6

10A

L

B-R

B-R

Fusible link

B-108

J/B

A/C 
compressor 
relay

B-104

1

A-130

MU802653

A/C refrigerant 
temperature 
switch

A/C compressor assembly

Magnetic 
clutch

A/C Compressor Relay 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   PU: Purple

AE

A-08

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

NOTE
*1: Vehicles with manual A/C
*2: Vehicles with automatic A/C

2

B-112

4

A-17

8

B-110

6

1 

3

4

2

G*1

V*2

81*1

110*2

Main

Index

Group

TOC

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI) <4A9>

13A-311

FUNCTION

• When the A/C 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 A/C compressor relay in the 
ON position. Accordingly, the battery voltage sup-
plied to the A/C compressor operates the magnet 
clutch.

PROBABLE CAUSES

• Failed A/C compressor relay

• Failed A/C compressor

• Open/short/damaged circuit in A/C compressor 

relay circuit or loose connector contact

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

<CVT>

DIAGNOSIS PROCEDURE

NOTE: 

.

*1: Vehicles with manual A/C
*2: Vehicles with automatic A/C

STEP 1. Connector check: B-104 A/C compressor 
relay connector

Q: Is the check result normal?

YES : 

Go to Step 2 .

NO : 

Repair or replace the connector.

STEP 2. A/C compressor relay check.

• Check A/C compressor relay (Refer to GROUP 

55 

− On-vehicle Service − Power Relay Check 

P.55A-52

).

Q: Is the check result normal?

YES : 

Go to Step 3 .

NO : 

Replace A/C compressor relay.

STEP 3. Perform voltage measurement at B-104 
A/C compressor assembly connector.

• Disconnect connector, and measure at harness 

side.

• Voltage between terminal No. 1, 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-104 (terminal No. 1 and 
No. 3) A/C compressor assembly connector 
and battery.

• Check power line for open/short 

circuit.

3

2

1

4

AK402066

B-104
J/B side 
connector

Connector: B-104
J/B (front side)

B-104

AC

3

2

1

4

AK402066

B-104
J/B side 
connector

Connector: B-104
J/B (front side)

B-104

AC

Main

Index

Group

TOC

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI) <4A9>

13A-312

STEP 4. Check harness between battery and 
B-104 (terminal No. 1 and No. 3) A/C compressor 
relay connector.

NOTE: Before checking harness, check intermediate 
connector B-108, and repair if necessary.

• Check power supply line for damage.

Q: Is the check result normal?

YES : 

Go to Step 5 .

NO : 

Repair the damaged harness wire.

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

AK402066

B-104
J/B side 
connector

Connector: B-104
J/B (front side)

B-104

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-313

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

• Disconnect connector, and measure at harness 

side.

• Voltage between terminal No. 81

*1

 or No. 110

*2 

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-104 (terminal No. 2) 
A/C compressor relay connector and A-08 
(terminal No. 81

*1

 or No. 110

*2

) engine-ECU 

connector or engine-CVT-ECU connector.

• Check signal line for open/short 

circuit.

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>

3

2

1

4

AK402066

B-104
J/B side 
connector

Connector: B-104
J/B (front side)

B-104

AC

Main

Index

Group

TOC