Mitsubishi Lancer Evolution X. Manual — part 436

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-809

.

CIRCUIT OPERATION

• The battery positive voltage is applied from the

MFI relay (terminal No. 2) to the ignition coil (ter-
minal No. 4) and is grounded to the vehicle body
via the ignition coil (terminal No. 5).

• A power voltage of 5 V is applied to the ignition

coil (terminal No. 2) from the ECM (terminal No.
4, No. 5, No. 20 and No. 21).

.

COMMENT

• When the ECM turn the power transistor in the

unit to OFF, the battery positive voltage is applied
to the power transistor in the ignition coil, result-
ing that the power transistor is ON. And, when
the ECM turns the power transistor in the unit to
ON, the power transistor in the ignition coil will be
turned OFF.

• When the power transistor in the ignition coil is

turned to ON with any signal from the ECM, the
primary voltage will be applied through the igni-
tion coil.When the power transistor in the ignition
coil is turned OFF, the primary current is blocked
and high voltage is generated in the secondary
coil.

.

TROUBLESHOOTING HINTS (The most
likely causes for this case:)

• Malfunction of the ignition coil.
• Open or shorted ignition circuit, harness damage,

or connector damage.

• Malfunction of the ECM.

DIAGNOSIS

STEP 1. Check the ignition coil.
Refer to GROUP 16, Ignition System − On-vehicle Service −

Ignition Coil Check

P.16-37

.

Q: Are there any abnormalities?

YES : Replace the ignition coil. Then confirm that the

malfunction symptom is eliminated.

NO : Go to Step 2.

AK704226

Connector: A-34X

MFI relay

A-34X

AB

AK704255AB

Connector: A-39

A-39 (B)

AK704599AB

B-02 (GR)

B-03 (GR)

B-04 (GR)

B-06 (GR)

Connectors: B-02, B-03, B-04 and B-06

AK704227

Connector: B-09

ECM

B-09 (GR)

AB

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

13A-810

STEP 2. Check harness connector B-02, B-03, B-04 and
B-06 at ignition coil for damage.
Q: Is the harness connector in good condition?

YES : Go to Step 3.
NO : Repair or replace it. Refer to GROUP 00E, Harness

Connector Inspection

P.00E-2

. Then confirm that the

malfunction symptom is eliminated.

STEP 3. Measure the power supply voltage at ignition coil
connectors B-02, B-03, B-04 and B-06.
(1) Disconnect the connector B-02, B-03, B-04 and B-06 and

measure at the harness side.

(2) Turn the ignition switch to the "ON" position.
(3) Measure the voltage between terminal No. 4 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 4.
NO : Check harness connector A-39 at intermediate

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

P.00E-2

. If intermediate connector is in

good condition, repair harness wire between MFI
relay connector A-34X (terminal No. 2) and ignition
coil connectors B-02, B-03, B-04 and B-06 (terminal
No. 4) because of open circuit or short circuit to
ground. Then confirm that the malfunction symptom is
eliminated.

STEP 4. Check the circuit at ignition coil harness side
connector B-02, B-03, B-04 and B-06.
(1) Disconnect the connectors B-02, B-03, B-04 and B-06 and

measure at the harness side.

(2) Engine: 3,000 r/min
(3) Measure the voltage between terminal No. 2 and ground.

• Voltage should be 0.3 and 3.0 volts.

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the measured voltage between 0.3 and 3.0 volts?

YES : Go to Step 7.
NO : Go to Step 5.

AK704600

2 1

3

4

B-02, B-03, B-04, B-06
harness connector:
component side

AB

AK704601

2 1

3

4

B-02, B-03, B-04, B-06
harness connector:
component side

AB

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

13A-811

STEP 5. Check harness connector B-09 at ECM for
damage.
Q: Is the harness connector in good condition?

YES : Go to Step 6.
NO : Repair or replace it. Refer to GROUP 00E, Harness

Connector Inspection

P.00E-2

. Then confirm that the

malfunction symptom is eliminated.

STEP 6. Check for open circuit and short circuit to ground
between ignition coil connector and ECM connector.

a. Check the harness wire between ignition coil connector

B-02 (terminal No. 2) and ECM connector B-09 (terminal
No. 4) at ignition coil 1.

b. Check the harness wire between ignition coil connector

B-03 (terminal No. 2) and ECM connector B-09 (terminal
No. 5) at ignition coil 2.

c. Check the harness wire between ignition coil connector

B-04 (terminal No. 2) and ECM connector B-09 (terminal
No. 20) at ignition coil 3.

d. Check the harness wire between ignition coil connector

B-06 (terminal No. 2) and ECM connector B-09 (terminal
No. 21) at ignition coil 4.

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, Diagnosis
− ID Code Registration Judgment Table <Vehicles with

KOS>

P.42B-14

or GROUP 42C, Diagnosis − ID

Codes Registration Judgment Table <Vehicles with
WCM>

P.42C-10

. Then confirm that the malfunction

symptom is eliminated.

NO : Repair it. Then confirm that the malfunction symptom

is eliminated.

STEP 7. Check for continuity at ignition coil harness side
connector B-02, B-03, B-04 and B-06.
(1) Disconnect the connectors B-02, B-03, B-04 and B-06 and

measure at the harness side.

(2) Check for the continuity between terminal No. 3 and

ground.

• Should be less than 2 ohms.

Q: Does continuity exist?

YES : Go to Step 8.
NO : Repair harness wire between ignition coil connectors

B-02, B-03, B-04 and B-06 (terminal No. 3) and
ground because of open circuit or harness damage.
Then confirm that the malfunction symptom is
eliminated.

AK704602

2 1

3

4

B-02, B-03, B-04, B-06
harness connector:
component side

AB

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

13A-812

STEP 8. Check for harness damage between MFI relay
connector A-34X (terminal No. 2) and ignition coil
connector B-02, B-03, B-04 and B-06 (terminal No. 4)
NOTE: Check harness after checking intermediate connector
A-39. If intermediate connector is damaged, repair or replace it.
After to GROUP 00E, Harness Connector Inspection

P.00E-2

.

Then check that the malfunction is eliminated.
Q: Is the harness wire in good condition?

YES : Go to Step 9.
NO : Repair it. Then confirm that the malfunction symptom

is eliminated.

STEP 9. Check for harness damage between ignition coil
connector and ECM connector.

a. Check the harness wire between ignition coil connector

B-02 (terminal No. 2) and ECM connector B-09 (terminal
No. 151) at ignition coil 1.

b. Check the harness wire between ignition coil connector

B-03 (terminal No. 2) and ECM connector B-09 (terminal
No. 143) at ignition coil 2.

c. Check the harness wire between ignition coil connector

B-04 (terminal No. 2) and ECM connector B-09 (terminal
No. 150) at ignition coil 3.

d. Check the harness wire between ignition coil connector

B-06 (terminal No. 2) and ECM connector B-09 (terminal
No. 148) at ignition coil 4.

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, Diagnosis
− ID Code Registration Judgment Table <Vehicles with

KOS>

P.42B-14

or GROUP 42C, Diagnosis − ID

Codes Registration Judgment Table <Vehicles with
WCM>

P.42C-10

. Then confirm that the malfunction

symptom is eliminated.

NO : Repair it. Then confirm that the malfunction symptom

is eliminated.