Mitsubishi Lancer Evolution X. Manual — part 255
MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS
TSB Revision
MULTIPORT FUEL INJECTION (MFI)
13A-85
.
CIRCUIT OPERATION
• Power is supplied from the MFI relay (terminal
No. 2) to the heated oxygen sensor (front) heater.
• The ECM (terminal No. 34) controls continuity to
the heated oxygen sensor (front) heater by turn-
ing the power transistor in the ECM "ON" and
"OFF".
.
TECHNICAL DESCRIPTION
• The ECM checks whether the heater current is
within a specified range when the heater is ener-
gized.
• The ECM checks whether the heater voltage is
within a specified range when the heater is not
energized.
.
DESCRIPTIONS OF MONITOR METHODS
Heated oxygen sensor heater (front) current or volt-
age is out of specified range.
.
MONITOR EXECUTION
Continuous
.
MONITOR EXECUTION CONDITIONS
(Other monitor and Sensor)
Other Monitor (There is no temporary DTC stored
in memory for the item monitored below)
• Not applicable
Sensor (The sensor below is determined to be
normal)
• Not applicable
.
AK704229AB
Connector: A-13
A-13
AK704226
Connector: A-34X
MFI relay
A-34X
AB
AK704227
Connector: B-09
ECM
B-09 (GR)
AB
AK704228
AB
Heated oxygen
sensor (front)
Connector: C-34
C-34 (B)
SRS-ECU
MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS
TSB Revision
MULTIPORT FUEL INJECTION (MFI)
13A-86
DTC SET CONDITIONS
Logic Flow Chart
.
Check Conditions
• More than 2 seconds have passed since the
engine starting sequence was completed.
• While the heated oxygen sensor (front) heater is
on.
• Battery positive voltage is between 11 and 16.5
volts.
Judgement Criterion
• The heated oxygen sensor (front) heater current
has continued to be lower than 0.17 ampere for 2
seconds.
Check Conditions
• More than 2 seconds have passed since the
engine starting sequence was completed.
• While the heated oxygen sensor (front) heater is
off.
• Battery positive voltage is between 11 and 16.5
volts.
Judgement Criterion
• The heated oxygen sensor (front) heater voltage
has continued to be lower than 2.0 volts for 2 sec-
onds.
.
End
No
No
Malfunction
Good
Current < 0.17A
or
Current > 10.5A
Voltage < 2.0V
AK900352
Heater activation
command ON
No
No
Start
Yes
Yes
Yes
Yes
Yes
No
Continuous
failure for 2secs
Monitoring
conditions
MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS
TSB Revision
MULTIPORT FUEL INJECTION (MFI)
13A-87
FAIL-SAFE AND BACKUP FUNCTION
• None
.
OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function − OBD-II Drive Cycle −
Pattern 2
.
.
TROUBLESHOOTING HINTS (The most
likely causes for this code to be set are:)
• Open or shorted heated oxygen sensor (front)
heater circuit, harness damage or connector
damage.
• Heated oxygen sensor (front) heater failed.
• ECM failed.
DIAGNOSIS
Required Special Tools:
• MB991658: Test Harness
• MB992110: Power Plant ECU Check Harness
STEP 1. Check harness connector C-34 at the heated
oxygen sensor (front) for damage.
Q: Is the harness connector in good condition?
YES : Go to Step 2.
NO : Repair or replace it. Refer to GROUP 00E, Harness
Connector Inspection
. Then go to Step 12.
STEP 2. Check the heated oxygen sensor (front).
(1) Disconnect heated oxygen sensor (front) connector C-34
and connect test harness special tool, MB991658, to the
connector on the heated oxygen sensor (front) side.
(2) Measure the resistance between heated oxygen sensor
connector terminal No. 1 and terminal No. 2.
Standard value: 4.5 − 8.0 Ω [at 20° C (68° F)]
Q: Is the measured resistance between 4.5 and 8.0 Ω [at
20° C (68° F)]?
YES : Go to Step 3.
NO : Replace the heated oxygen sensor (front). Then go to
Step 12.
STEP 3. Measure the power supply voltage at heated
oxygen sensor (front) harness side connector C-34.
(1) Disconnect the connector C-34 and measure at the harness
side.
(2) Turn the ignition switch to the "ON" position.
(3) Measure the voltage between terminal No. 1 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 5.
NO : Go to Step 4.
AK604492AB
MB991658
Heated oxygen
sensor component
side connector
AK604172
2 1
4 3
C-34 harness
connector:
component side
AH
MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS
TSB Revision
MULTIPORT FUEL INJECTION (MFI)
13A-88
STEP 4. Check harness connector A-34X at the MFI relay
for damage.
Q: Is the harness connector in good condition?
YES : Repair harness wire between MFI relay connector
A-34X (terminal No. 2) and heated oxygen sensor
(front) connector C-34 (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
. 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. 34 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
AK604173
16 15 14 13 12 11 10 9 8 7 6 5 4 3
2
1
32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17
48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33
64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49
AB
Power plant ECU
check harness connector
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