Mitsubishi Colt Ralliart. Manual — part 84
TROUBLESHOOTING
MULTIPORT FUEL INJECTION (MPI) <4A9>
13A-290
OPERATION
• The battery voltage is applied to the fuel pump
relay (1) (terminal No. 1) form the ignition switch
and is earthed to the vehicle body from the fuel
pump relay (1) (terminal No. 2).
• The battery voltage is applied to the fuel pump
relay (1) (terminal No. 3) and to the fuel pump
relay (2) (terminal No. 3) from the fuel pump relay
(1) (terminal No. 4).
• The battery voltage is applied to the fuel pump
relay (2) (terminal No. 1) from the ignition switch.
The engine-ECU <M/T> or engine-CVT-ECU
<CVT> (terminal No. 110) makes the power tran-
sistor in the unit be in ON position and makes
currents go on the fuel pump relay (2) coil, and
that makes the relay be in ON position.
• When the fuel pump relay (2) is in ON position,
the battery voltage is supplied to the fuel pump
(low pressure) from the fuel pump relay (2) (ter-
minal 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 fuel pump relay (2) in the ON
position. Accordingly, the battery voltage is sup-
plied to the fuel pump.
PROBABLE CAUSES
• Failed fuel pump relay
• Failed fuel pump
• Open/short/damaged circuit in fuel pump drive
circuit or loose connector contact
• Failed engine-ECU <M/T> or engine-CVT-ECU
<CVT>
DIAGNOSIS PROCEDURE
STEP 1. Connector check: B-117 fuel pump relay
(1) connector and B-103 fuel pump relay (2)
connector
Q: Is the check result normal?
YES :
Go to Step 2 .
NO :
Repair or replace the connector.
STEP 2. Check fuel pump relay.
• Fuel pump relay, continuity check (Refer to
).
Q: Is the check result normal?
YES :
Go to Step 3 .
NO :
Replace fuel pump relay.
AK402061
3
2
1
4
AC
B-103, B-117
J/B side
connector
Connector: B-103, B-117
J/B (front side)
B-117
B-103
Main
Index
Group
TOC
TROUBLESHOOTING
MULTIPORT FUEL INJECTION (MPI) <4A9>
13A-291
STEP 3. Perform resistance measurement at
B-117 fuel pump relay (1) connector.
• Remove relay, and measure at junction block
side.
• Resistance between terminal No. 2 and earth.
OK: Continuity (2
Ω or less)
Q: Is the check result normal?
YES :
Go to Step 4 .
NO :
Check intermediate connector B-130, and
repair if necessary. If intermediate
connector is normal, check and repair
harness between B-117 (terminal No. 2) fuel
pump relay (1) connector and body earth.
• Check earthing line for open circuit
and damage.
STEP 4. Perform voltage measurement at B-117
fuel pump relay (1) connector.
• Remove relay, and measure at junction block
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 .
AK402062
3
2
1
4
AC
B-117
J/B side
connector
Connector: B-117
J/B (front side)
B-117
AK402062
3
2
1
4
AC
B-117
J/B side
connector
Connector: B-117
J/B (front side)
B-117
Main
Index
Group
TOC
TROUBLESHOOTING
MULTIPORT FUEL INJECTION (MPI) <4A9>
13A-292
STEP 5. Connector check: B-141 ignition switch
connector
Q: Is the check result normal?
YES :
Check intermediate connector B-129, and
repair if necessary. If intermediate
connector is normal, check and repair
harness between B-117 (terminal No. 1) fuel
pump relay (1) connector and B-141
(terminal No. 2) ignition switch connector.
• Check power supply line for open
circuit and damage.
NO :
Repair or replace the connector.
STEP 6. Perform voltage measurement at B-117
fuel pump relay (1) connector.
• Remove relay, and measure at junction block
side.
• Voltage between terminal No. 3 and earth.
OK: System voltage
Q: Is the check result normal?
YES :
Go to Step 7 .
NO :
Check intermediate connectors B-108, and
repair if necessary. If intermediate
connectors are normal, check and repair
harness between B-117 (terminal No. 3) fuel
pump relay (1) connector and battery.
• Check power supply line for
open/short circuit.
AK402054
B-141
AC
Connector: B-141
1
2
3
4
5
6
B-141 Harness
side connector
AK402062
3
2
1
4
AC
B-117
J/B side
connector
Connector: B-117
J/B (front side)
B-117
AK402062
3
2
1
4
AC
B-117
J/B side
connector
Connector: B-117
J/B (front side)
B-117
Main
Index
Group
TOC
TROUBLESHOOTING
MULTIPORT FUEL INJECTION (MPI) <4A9>
13A-293
STEP 7. Perform resistance measurement at
B-103 fuel pump relay (2) connector.
• Remove relay, and measure at junction block
side.
• Ignition switch: ST
• Resistance between terminal No. 2 and earth.
OK: Continuity
Q: Is the check result normal?
YES :
Go to Step 11 .
NO :
Go to Step 8 .
STEP 8. Connector check: A-08 engine-ECU
connector or engine-CVT-ECU connector
Q: Is the check result normal?
YES :
Go to Step 9 .
NO :
Repair or replace the connector.
AK402063
3
2
1
4
AC
B-103
J/B side
connector
Connector: B-103
J/B (front side)
B-103
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
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