Mitsubishi Colt Ralliart. Manual - part 22

 

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Mitsubishi Colt Ralliart. Manual - part 22

 

 

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI) <4A9>

13A-42

Code No. P0115: Engine Coolant Temperature Sensor System

OPERATION

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

coolant temperature sensor output terminal (ter-
minal No. 1) from the engine-ECU <M/T> or 
engine-CVT-ECU <CVT> (terminal No. 14).

• The power voltage is earthed to the engine-ECU 

<M/T> or engine-CVT-ECU <CVT> (terminal No. 
29) from the engine coolant temperature sensor 
(terminal No. 2).

FUNCTION

• The engine coolant temperature sensor converts 

the engine coolant temperature into a voltage sig-
nal, and inputs the voltage to the engine-ECU 
<M/T> or engine-CVT-ECU <CVT>.

• In response to the signal, the engine-ECU <M/T> 

or engine-CVT-ECU <CVT> controls the fuel 
infection amount and the fast idle speed when the 
engine is cold state.

• The engine coolant temperature sensor is a kind 

of resistor, which has characteristics to reduce its 
resistance as the engine coolant temperature 
rises. Therefore, the sensor output voltage varies 
with the engine coolant temperature, and 
becomes lower as the engine coolant tempera-
ture rises.

AK402678

1 2

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38 39 404142434445464748495051

22 23 24 252627282930313233343536

7

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3

1

6

4

2

29

14

A-114

Engine-ECU <M/T> or
engine-CVT-ECU <CVT>

Engine coolant
temperature sensor

Y-G

B

A-121

 (MU802406)

2

1

5 V

Engine Coolant Temperature Sensor Circuit

AD

Wire colour code
B: Black  LG: Light green  G: Green  L: Blue  W: White  Y: Yellow  SB: Sky blue  BR: Brown  O: Orange  GR: Gray
R: Red  P: Pink  V: Violet  Pu: Purple

Main

Index

Group

TOC

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI) <4A9>

13A-43

TROUBLE JUDGMENT

Check Condition

• 2 seconds later after the ignition switch has been 

in ON position or just after the engine has started 
up.

Judgment Criteria

• The sensor output voltage is 4.6 V or more (water 

temperature of below 

−40°C or equivalent) for 4 

seconds.

or

• The sensor output voltage is 0.1 V or less (water 

temperature of above 120

°C or equivalent) for 4 

seconds.

Check Condition

• 2 seconds later after the engine has started up.

Judgment Criteria

• The sensor output voltage rises 1.6 V or more 

(engine coolant temperature below 40

°C or 

equivalent) from 1.6 V or less (engine coolant 
temperature above 40

°C or equivalent).

• For the following 5 minutes, the sensor output 

voltage should be 1.6 V or more (engine coolant 
temperature above 40

°C or equivalent) <M/T>.

PROBABLE CAUSES

• Failed engine coolant temperature sensor

• Open/short circuit in engine coolant temperature 

sensor circuit or loose connector contact

• Failed engine-ECU <M/T> or engine-CVT-ECU 

<CVT>

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III data list

• Item 21: Engine coolant temperature sensor

OK:

Engine cold state: At ambient temperature 

(atmospheric temperature) or equivalent.

Engine hot state: At 80 

 120°C

Q: Is the check result normal?

YES : 

Intermittent malfunction (Refer to GROUP 

00 

− How to Use 

Troubleshooting/Inspection Service Points 

− 

How to Cope with Intermittent Malfunctions 

P.00-13

).

NO : 

Go to Step 2 .

STEP 2. Connector check: A-121 engine coolant 
temperature sensor connector

Q: Is the check result normal?

YES : 

Go to Step 3 .

NO : 

Repair or replace the connector.

STEP 3. Perform resistance measurement at 
A-121 engine coolant temperature sensor 
connector.

• Disconnect connector, and measure at sensor 

side.

• Resistance between terminal No. 1 and No. 2.

OK:

Engine coolant temperature at 

20°C: 14  17 

k

Engine coolant temperature at 0

°C: 5.1  6.5 

k

Engine coolant temperature at 20

°C: 2.1  2.7 

k

Engine coolant temperature at 40

°C: 0.9  1.3 

k

Engine coolant temperature at 60

°C: 0.48  

0.68 k

Engine coolant temperature at 80

°C: 0.26  

0.36 k

Q: Is the check result normal?

YES : 

Go to Step 4 .

NO : 

Replace engine coolant temperature 
sensor.

AK402011

1

2

Connector: A-121

A-121 (B)

AD

A-121 Harness side 
connector

AK402011

1

2

Connector: A-121

A-121 (B)

AD

A-121 Harness side 
connector

Main

Index

Group

TOC

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI) <4A9>

13A-44

STEP 4. Perform voltage measurement at A-121 
engine coolant temperature sensor connector.

• Disconnect connector and measure at harness 

side.

• Ignition switch: ON

• Voltage between terminal No. 1 and earth.

OK: 4.5 

 4.9 V

Q: Is the check result normal?

YES : 

Go to Step 10 .

NO : 

Go to Step 5 .

STEP 5. Perform voltage measurement at A-114 
engine-ECU connector or engine-CVT-ECU 
connector.

• Disconnect engine-ECU connector or 

engine-CVT-ECU connector, and connect special 
tool power plant ECU check harness 
(MB991987), and then measure the voltage on 
the check connector.

• Disconnect A-121 engine coolant temperature 

sensor connector.

• Ignition switch: ON

• Voltage between terminal No. 14 and earth.

OK: 4.5 

 4.9 V 

Q: Is the check result normal?

YES : 

Go to Step 6 . 

NO : 

Go to Step 7 

AK402011

1

2

Connector: A-121

A-121 (B)

AD

A-121 Harness side 
connector

AK402745

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L

AE

A-114

Connector: 

A-114

Engine-ECU <M/T> or
engine-CVT-ECU <CVT>

Battery

A-114 Special tool power plant ECU check 
harness

AK402011

1

2

Connector: A-121

A-121 (B)

AD

A-121 Harness side 
connector

Main

Index

Group

TOC

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI) <4A9>

13A-45

STEP 6. Connector check: A-114 engine-ECU 
connector or engine-CVT-ECU connector

Q: Is the check result normal?

YES : 

Check and repair harness between A-121 

(terminal No. 1) engine coolant temperature 
sensor connector and A-114 (terminal No. 
14) engine-ECU connector or 
engine-CVT-ECU connector.

• Check output line for open circuit.

NO : 

Repair or replace the connector.

STEP 7. Connector check: A-114 engine-ECU 
connector or engine-CVT-ECU connector

Q: Is the check result normal?

YES : 

Go to Step 8 .

NO : 

Repair or replace the connector.

AK402745

6

4

2

5

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1

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L

AD

A-114

Connector: 

A-114

Harness side connector

Engine-ECU <M/T> or
engine-CVT-ECU <CVT>

Battery

AK402011

1

2

Connector: A-121

A-121 (B)

AD

A-121 Harness side 
connector

AK402745

6

4

2

5

3

1

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AD

A-114

Connector: 

A-114

Harness side connector

Engine-ECU <M/T> or
engine-CVT-ECU <CVT>

Battery

Main

Index

Group

TOC

 

 

 

 

 

 

 

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