Mitsubishi Lancer Evolution X. Manual — part 427
MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS
TSB Revision
MULTIPORT FUEL INJECTION (MFI)
13A-773
• When the fuel pump relay 2 is turned ON, the fuel
pump drive power is supplied from the fuel pump
relay 2 (C-314 ETACS-ECU connector terminal
No. 1) to the fuel pump (terminal No. 5).
• When the vehicle is driven at low engine loads,
the ECM (terminal No. 51) turns OFF the power
transistor of the unit. The current is not going
through the fuel pump relay 1, and then the relay
is turned OFF.
• When the vehicle is driven at high engine loads,
the ECM (terminal No. 51) turns ON the power
transistor of the unit. The current is going through
the fuel pump relay 1 (terminal No. 1), and then
the relay is turned ON. Thus the fuel pump drive
power is supplied from the fuel pump relay 1 (ter-
minal No. 3) to the fuel pump relay 2 (C-307
ETACS-ECU connector terminal No. 1).
.
COMMENT
• The ECM turns ON the fuel pump relay 2 during
the engine cranking and running, and then sup-
plies the drive power to the fuel pump.
• The ECM supplies the drive power to the fuel
pump via the resistor during the engine running at
low engine loads. The ECM supplies the drive
power directly to the fuel pump during the engine
running at high engine loads to increase the fuel
discharge rate of fuel pump.
.
TROUBLESHOOTING HINTS (The most
likely causes for this case:)
• Malfunction of the fuel pump relay 1.
• Malfunction of fuel pump relay 2 of ETACS-ECU.
• Malfunction of the fuel pump.
• Malfunction of the fuel pump circuit resistor.
• Improper connector contact, open or short-circu-
lated harness wire.
• Malfunction of the ECM.
DIAGNOSIS
Required Special Tools:
• MB991958: Scan Tool (M.U.T.-III Sub Assembly)
• MB991824: V.C.I.
• MB991827: USB Cable
• MB991910: Main Harness A
STEP 1. Check harness connector C-304, C-307, C314 and
C-317 at ETACS-ECU for damage.
Q: Is the connector in good condition?
YES : Go to Step 2.
NO : Repair or replace it. Refer to GROUP 00E, Harness
Connector Inspection
. Then confirm that the
malfunction symptom is eliminated.
MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS
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MULTIPORT FUEL INJECTION (MFI)
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STEP 2. Check the fuel pump relay 2.
(1) Remove the ETACS-ECU.
(2) Use jumper wires to connect C-317 ETACS-ECU terminal
No. 6 to the positive battery terminal and C-304
ETACS-ECU terminal No. 11 to the negative battery
terminal.
(3) Check for continuity between the C-307 ETACS-ECU
terminal No. 1 and C-314 ETACS-ECU terminal No. 1 while
connecting and disconnecting the jumper wire at the
negative battery terminal.
• Continuity (2 Ω or less) <Negative battery terminal con-
nected>
• Should be open loop. <Negative battery terminal discon-
nected>
(4) Install the ETACS-ECU.
Q: Is the measured resistance normal?
YES : Go to Step 3.
NO : Replace the ETACS-ECU. Then confirm that the
malfunction symptom is eliminated.
STEP 3. Check harness connector A-27X at fuel pump
relay 1 for damage.
Q: Is the connector in good condition?
YES : Go to Step 4.
NO : Repair or replace it. Refer to GROUP 00E, Harness
Connector Inspection
. Then confirm that the
malfunction symptom is eliminated.
1 2 3 4
5 6 7
8 9 10 11
131415
12
1 2
1 2
1
6
4
5
9
8
10 11
13
15
14
12
16
7
2 3
AK703917AC
C-314
ETACS-ECU
side connector
C-307
ETACS-ECU
side connector
C-304
ETACS-ECU
side connector
C-317 ETACS-ECU
side connector
MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS
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MULTIPORT FUEL INJECTION (MFI)
13A-775
STEP 4. Check the fuel pump relay 1.
(1) Remove the fuel pump relay 1.
(2) Check for continuity between the throttle actuator control
motor relay terminal No. 1 and No. 2.
• There should be continuity.
(3) Use jumper wires to connect fuel pump relay 1 terminal No.
2 to the positive battery terminal and terminal No. 1 to the
negative battery terminal.
(4) Check the continuity between the fuel pump relay 1
terminal No. 3 and No. 4 while connecting and
disconnecting the jumper wire at the negative battery
terminal.
• Continuity (2 Ω or less) <Negative battery terminal con-
nected.>
• Should be open loop. <Negative battery terminal discon-
nected.>
(5) Install the throttle actuator control motor relay.
Q: Is the measured resistance normal?
YES : Go to Step 5.
NO : Replace the fuel pump relay 1. Then confirm that the
malfunction symptom eliminated.
STEP 5. Check harness connector A-58 fuel pump circuit
resistor.
Q: Is the connector in good condition?
YES : Go to Step 6.
NO : Repair or replace it. Refer to GROUP 00E, Harness
Connector Inspection
. Then confirm that the
malfunction symptom is eliminated.
STEP 6. Check the fuel pump circuit resistor.
(1) Disconnect the fuel pump circuit resistor connector.
(2) Measure the resistance between terminals.
Standard value: 0.45 − 0.65 Ω [at 20° C (68° F)]
Q: Is the measured resistance normal?
YES : Go to Step 7.
NO : Replace the fuel pump circuit resistor. Then confirm
that the malfunction symptom eliminated.
AK604234
1
2
3
4
Fuel pump relay 1
side connector
AC
AK604235
1
2
3
4
AD
Fuel pump relay 1
side connector
1 2
AK202413 AC
Fuel pump circuit
resistor side connector
MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS
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MULTIPORT FUEL INJECTION (MFI)
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STEP 7. Check harness connector B-10 at ECM for
damage.
Q: Is the connector in good condition?
YES : Go to Step 8.
NO : Repair or replace it. Refer to GROUP 00E, Harness
Connector Inspection
. Then confirm that the
malfunction symptom is eliminated.
STEP 8. Measure the power supply voltage at ECM
connector B-10.
(1) Disconnect the connector B-10 and measure at the harness
side.
(2) Turn the ignition switch to the "ON" position.
(3) Measure the voltage between terminal No. 96 and ground.
• Voltage should be battery positive voltage.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is battery positive voltage (approximately 12 volts)
present?
YES : Go to Step 9.
NO : Repair harness wire between ETACS-ECU connector
C-304 (terminal No. 11) and ECM connector B-10
(terminal No. 96) because of open circuit. Then
confirm that the malfunction symptom is eliminated.
STEP 9. Check harness connector B-09 at ECM for
damage.
Q: Is the connector in good condition?
YES : Go to Step 10.
NO : Repair or replace it. Refer to GROUP 00E, Harness
Connector Inspection
. Then confirm that the
malfunction symptom is eliminated.
AK604054
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105
118
117
82 81 80 79 78 77 76 75 74 73 72 71
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100
101
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106
112
113
114
109 108
107
110
111
115
116
117
118
AC
B-10 harness
connector:
component side
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