Mitsubishi Montero (2004+). Manual - part 157

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

13A-115

CIRCUIT OPERATION

• 5-volt voltage is applied to the engine coolant

temperature sensor output terminal (terminal No.
1) from the PCM (terminal No. 98) via the resistor
in the PCM. The ground terminal (terminal No. 2)
is grounded with PCM (terminal No. 96).

• The engine coolant temperature sensor is a neg-

ative temperature coefficient type of resistor. It
has the characteristic that when the engine cool-
ant temperature rises the resistance decreases.

• The engine coolant temperature sensor output

voltage increases when the resistance increases
and decreases when the resistance decreases.

TECHNICAL DESCRIPTION

• The engine coolant temperature sensor converts

the engine coolant temperature to a voltage and
outputs it.

• The PCM checks whether this voltage is within a

specified range.

DESCRIPTIONS OF MONITOR METHODS
Engine coolant temperature sensor output voltage

does not change for specified period when
engine coolant temperature sensor output volt-
age at engine start is over 7

°C (45°F).

MONITOR EXECUTION
Once per driving cycle

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)

• Volume airflow sensor

• Engine coolant temperature sensor

• Intake air temperature sensor

AK200942

ENGINE COOLANT
TEMPERATURE SENSOR

AK200942AB

B-37(B)

CONNECTOR: B-37

AK201038AF

CONNECTOR: D-135

PCM

D-135(GR)

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

13A-116

DTC SET CONDITIONS

Logic Flow Chart

Check Conditions

• Engine coolant temperature was 7°C (45°F) or

more immediately before the engine was stopped
at the last drive.

• Engine coolant temperature was 7°C (45°F) or

more when the engine started.

Judgement Criteria

• Engine coolant temperature fluctuates within 1°C

(1.8

°F) after 5 minutes have passed since the

engine was started.

• However, time is not counted if any of the follow-

ing conditions are met.

1. Intake air temperature is 60

°C (140°F) or

more.

2. Volume airflow sensor output frequency is 70

Hz or less.

3. During fuel shut-off operation.

• The PCM monitors for this condition once during

the drive cycle.

START

END

YES

MALFUNCTION

GOOD

300secs HAVE PASSED?

|dT| < 1˚C(1.8˚F)

MONITORING CONDITIONS?

START MEASURING THE MINIMUM AND MAXIMUM

TEMPERATURE FROM ENGINE START

CALCULATE THE DIFFERENCE OF THE MINIMUM AND

THE MAXIMUM TEMPERATURE FROM ENGINE START;dT

YES

AK302924

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

13A-117

OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function

− OBD-II Drive Cycle −

Procedure 6

− Other Monitor

P.13A-4

TROUBLESHOOTING HINTS (The most likely
causes for this code to be set are: )

• Engine coolant temperature sensor failed.

• Harness damage or connector damage.

• PCM failed.

DIAGNOSIS

Required Special Tools:

• MB991958: Scan Tool (MUT-III Sub Assembly)

• MB991824: V.C.I.

• MB991827: USB Cable

• MB991911: Main Harness B

STEP 1. Using scan tool MB991958, check data list item 21:
Engine Coolant Temperature Sensor.

CAUTION

To prevent damage to scan tool MB991958, always turn the
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting scan tool MB991958.
(1) Connect scan tool MB991958 to the data link connector.
(2) Turn the ignition switch to the "ON" position.
(3) Set scan tool MB991958 to the data reading mode for item

21, Engine Coolant Temperature Sensor.

• The engine coolant temperature and temperature

shown with the scan tool should approximately match.

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the sensor operating properly?

YES : It can be assumed that this malfunction is intermittent.

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

P.00-6

NO : Go to Step 2.

AK302970

MB991911

MB991824

MB991827

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

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STEP 2. Check the sensor output voltage at engine coolant
temperature sensor connector B-37 by backprobing.
(1) Do not disconnect the connector B-37.
(2) Turn the ignition switch to the "ON" position.

(3) Measure the voltage between terminal No. 1 and ground by

backprobing.

• When engine coolant temperature is −20°C (−4°F), volt-

age should be between 3.9 and 4.5 volts.

• When engine coolant temperature is 0°C (32°F), voltage

should be between 3.2 and 3.8 volts.

• When engine coolant temperature is 20°C (68°F), volt-

age should be between 2.3 and 2.9 volts.

• When engine coolant temperature is 40°C (104°F), volt-

age should be between 1.3 and 1.9 volts.

• When engine coolant temperature is 60°C (140°F), volt-

age should be between 0.7 and 1.3 volts.

• When engine coolant temperature is 80°C (176°F), volt-

age should be between 0.3 and 0.9 volt.

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the voltage normal?

YES : Go to Step 3.
NO : Go to Step 5.

STEP 3. Check connector B-37 at the engine coolant
temperature sensor 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

P.00E-2

. Then go to Step 14.

AK200943

HARNESS
CONNECTOR:
COMPONENT SIDE

CONNECTOR: B-37

B-37(B)

AK201572

B-37 HARNESS
CONNECTOR:
HARNESS SIDE

AK200943

HARNESS
CONNECTOR:
COMPONENT SIDE

CONNECTOR: B-37

B-37(B)

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