Mitsubishi Evolution X. Manual - part 276

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-81

STEP 4. Check harness connector A-34X at the MFI relay 
for damage.
Q: Is the harness connector in good condition?

YES : Check harness connectors C-43 and C-47 at 

intermediate connectors for damage, and repair or 
replace as required. Refer to GROUP 00E, Harness 
Connector Inspection 

P.00E-2

. If intermediate 

connectors are in good condition, repair harness wire 
between MFI relay connector A-34X (terminal No. 2) 
and heated oxygen sensor (rear) connector D-35 
(terminal No. 1) because of open circuit or short 
circuit to ground. Then go to Step 12.

NO :  Repair or replace it. Refer to GROUP 00E, Harness 

Connector Inspection 

P.00E-2

. Then go to Step 12.

STEP 5. Measure the power supply voltage at ECM 
connector B-09 by using power plant ECU check harness 
special tool MB992110.
(1) Disconnect all ECM connectors. Connect the power plant 

ECU check harness special tool MB992110 between the 
separated connectors.

(2) Turn the ignition switch to the "ON" position.

(3) Measure the voltage between terminal No. 35 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 8.
NO :  Go to Step 6.

AK604040

ECM

AB

Body side harness 

MB992110

AK604174

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64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49

AB

Power plant ECU
check harness connector

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

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STEP 6. Check harness connector B-09 at ECM for 
damage.
Q: Is the harness connector in good condition?

YES : Go to Step 7.
NO :  Repair or replace it. Refer to GROUP 00E, Harness 

Connector Inspection 

P.00E-2

. Then go to Step 12.

STEP 7. Check for open circuit and short circuit to ground 
between heated oxygen sensor (rear) connector D-35 
(terminal No. 2) and ECM connector B-09 (terminal No. 35).
NOTE: Check harness after checking intermediate connectors 
A-13 and C-45. If intermediate connectors are damaged, repair 
or replace them. Refer to GROUP 00E, Harness Connector 
Inspection 

P.00E-2

. Then go to Step 12.

Q: Is the harness wire in good condition?

YES : Replace the ECM. When the ECM is replaced, 

register the ID code. Refer to GROUP 42B, ID Code 
Registration Necessity Judgment Table <Vehicles 
with KOS> 

P.42B-12

 or GROUP 42C, ID Codes 

Registration Judgment Table <Vehicles with WCM> 

P.42C-9

. Then go to Step 12.

NO :  Repair it. Then go to Step 12.

STEP 8. Check harness connector B-09 at ECM for 
damage.
Q: Is the harness connector in good condition?

YES : Go to Step 9.
NO :  Repair or replace it. Refer to GROUP 00E, Harness 

Connector Inspection 

P.00E-2

. Then go to Step 12.

STEP 9. Check for harness damage between MFI relay 
connector A-34X (terminal No. 2) and heated oxygen 
sensor (rear) connector D-35 (terminal No. 1).
NOTE: Check harness after checking intermediate connectors 
C-43 and C-47. If intermediate connectors are damaged, repair 
or replace them. Refer to GROUP 00E, Harness Connector 
Inspection 

P.00E-2

. Then go to Step 12.

Q: Is the harness wire in good condition?

YES : Go to Step 10.
NO :  Repair it. Then go to Step 12.

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

13A-83

STEP 10. Check for harness damage between heated 
oxygen sensor (rear) connector D-35 (terminal No. 2) and 
ECM connector B-09 (terminal No. 35).
NOTE: Check harness after checking intermediate connectors 
A-13 and C-45. If intermediate connectors are damaged, repair 
or replace them. Refer to GROUP 00E, Harness Connector 
Inspection 

P.00E-2

. Then go to Step 12.

Q: Is the harness wire in good condition?

YES : Go to Step 11.
NO :  Repair it. Then go to Step 12.

STEP 11. Check the trouble symptoms.
(1) Carry out a test drive with the drive cycle pattern. Refer to 

Diagnostic Function 

− OBD-II Drive Cycle − Pattern 2 

P.13A-9

.

(2) Check the diagnostic trouble code (DTC).
Q: Is DTC P0037 set?

YES : Replace the ECM. When the ECM is replaced, 

register the ID code. Refer to GROUP 42B, ID Code 
Registration Necessity Judgment Table <Vehicles 
with KOS> 

P.42B-12

 or GROUP 42C, ID Codes 

Registration Judgment Table <Vehicles with WCM> 

P.42C-9

. Then go to Step 12.

NO :  It can be assumed that this malfunction is intermittent. 

Refer to GROUP 00, How to Use 
Troubleshooting/Inspection Service Points 

− How to 

Cope with Intermittent Malfunctions 

P.00-15

. 

STEP 12. Test the OBD-II drive cycle.
(1) Carry out a test drive with the drive cycle pattern. Refer to 

Diagnostic Function 

− OBD-II Drive Cycle − Pattern 2 

P.13A-9

.

(2) Check the diagnostic trouble code (DTC).
Q: Is DTC P0037 set?

YES : Retry the troubleshooting.
NO :  The inspection is complete.

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

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DTC P0038: Heated Oxygen Sensor (rear) Heater Circuit High

AK704230

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WHITE

WHITE

HEATED OXYGEN SENSOR (REAR) HEATER CIRCUIT

36

FUSIBLE LINK

AB

D-35

4

1

20A

WHITE

A-34X

4

3

1

2

22

C-47

B-09

OFF

ON

C-43

1

4

2

3

RED-

GREEN

RED-

GREEN

11

10

2

C-45

A-13

35

J/C(4)

HEATED OXYGEN SENSOR
(REAR)

RELAY BOX
(ENGINE COMPARTMENT)

BR

O

W

N

BR

O

W

N

ENGINE
CONTROL
MODULE

TO ECM

TO ECM

TO ECM

MFI
RELAY

BR

O

W

N