Mitsubishi Montero (2004+). Manual - part 161

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-131

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 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

.

DTC SET CONDITIONS

Logic Flow Chart

Check Conditions

• 2 seconds or more have passed since the engine 

starting sequence was completed.

START

OUTPUT VOLTAGE > 4.6V

OUTPUT VOLTAGE < 0.1V

END

NO

NO

NO

YES

YES

YES

MALFUNCTION

GOOD

CONTINUOUS

FAILURE FOR 2secs

MONITORING

CONDITIONS?

NO

YES

AK302925

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-132

Judgement Criteria

• Engine coolant temperature sensor output volt-

age has continued to be 4.6 volts or higher [cor-
responding to coolant temperature of 

−45°C 

(

−49°F) or lower] for 2 seconds.

.

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.

• Open engine coolant temperature sensor circuit, 

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.

STEP 2. Check connector B-37 at the engine coolant 
temperature sensor for damage.
Q: Is the 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 go to Step 11.

AK302970

AB

MB991911

MB991824

MB991827

AK200943

1

2

AB

HARNESS 
CONNECTOR: 
COMPONENT SIDE

CONNECTOR: B-37

B-37(B)

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-133

STEP 3. Measure the sensor supply voltage at engine 
coolant temperature sensor harness side connector B-37.
(1) Disconnect the connector B-37 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 between 4.5 and 4.9 volts.

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the measured voltage between 4.5 and 4.9 volts?

YES : Go to Step 7.
NO :  Go to Step 4.

STEP 4. Measure the sensor supply voltage at PCM 
connector D-135 by backprobing.
(1) Do not disconnect the PCM connector D-135.
(2) Disconnect the engine coolant temperature sensor 

connector B-37.

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

(4) Measure the voltage between terminal No. 98 and ground 

by backprobing.

• Voltage should be between 4.5 and 4.9 volts.

(5) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the measured voltage between 4.5 and 4.9 volts?

YES : Go to Step 5.
NO :  Go to Step 6.

AK200943

1

2

AB

HARNESS 
CONNECTOR: 
COMPONENT SIDE

CONNECTOR: B-37

B-37(B)

AK000234 AL

2 1

B-37 HARNESS 
CONNECTOR: 
COMPONENT SIDE

AK200947

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99

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CONNECTOR: D-135

HARNESS CONNECTOR: 
COMPONENT SIDE

AB

PCM

D-135(GR)

AK201395

9192

939495

96979899

100 101102103

104

105106

107108109

110111112

113114

115116117

118119120

AB

D-135 HARNESS 
CONNECTOR: 
HARNESS SIDE

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-134

STEP 5. Check connector D-135 at PCM for damage.
Q: Is the connector in good condition?

YES : Repair harness wire between engine coolant 

temperature sensor connector B-37 (termial No. 1) 
and PCM connector D-135 (termial No. 98) because 
of open circuit. Then go to Step 11.

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

Connector Inspection 

P.00E-2

. Then go to Step 11.

STEP 6. Check connector D-135 at PCM for damage.
Q: Is the connector in good condition?

YES : Replace the PCM. Then go to Step 11.
NO :  Repair or replace it. Refer to GROUP 00E, Harness 

Connector Inspection 

P.00E-2

. Then go to Step 11.

AK200947

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CONNECTOR: D-135

HARNESS CONNECTOR: 
COMPONENT SIDE

AB

PCM

D-135(GR)

AK200947

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CONNECTOR: D-135

HARNESS CONNECTOR: 
COMPONENT SIDE

AB

PCM

D-135(GR)