Mitsubishi Colt Ralliart. Manual - part 713

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI) <4G1>

13B-177

Code No. P0642: Throttle Position Sensor Power Supply

FUNCTION

• Engine-ECU checks the throttle position sensor 

power voltage for abnormal conditions.

TROUBLE JUDGMENT

Check Conditions

• Ignition switch is in "ON" position.

• Battery positive voltage is more than 6.3 V.

Judgement Criteria

• Throttle position sensor power voltage is less 

than 4.1 V.

PROBALE CAUSE

• Failed engine-ECU <M/T>

DIAGNOSIS

STEP 1. Check the trouble symptoms.

Q: Does trouble symptom persist?

YES : 

Replace engine-ECU.

NO : 

Intermittent malfunction (Refer to GROUP 
00 

− How to Use 

Troubleshooting/Inspection Service Points 

− 

How to Cope with Intermittent Malfunctions 

P.00-13

).

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TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI) <4G1>

13B-178

Code No. P0657: Throttle Valve Control Servo Relay Circuit Malfunction

OPERATION

• Battery voltage is applied to the throttle valve 

control servo relay terminal (terminal No. 3).

• Battery voltage is applied to the throttle valve 

control servo relay terminal (terminal No. 1) from 
the engine control relay (terminal No. 4).

• Engine-ECU (terminal No. 123) applies current to 

the throttle valve control servo relay coil by turn-
ing ON the power transistor in the unit in order to 
turn the relay ON.

• When the throttle valve control servo relay turns 

ON, battery voltage is supplied by the throttle 
valve control servo relay (terminal No. 4) to the 
engine-ECU (terminal No. 78).

AK503598

3

1

2

4

3

1

2

4

R

92 93 94 95969798

77 78 79 808182838485868788899091

99

100

107 108 109 110 111112113114115116117118119120121
122 123 124 125126127128129130131132133134135136

101102103104105106

71 72

73 74

75 76

AD

Power source

L-W

R-L

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

  P: Purple

Engine-ECU

Throttle Valve Control Servo Relay Circuit

Engine
control
relay

Throttle 
valve
control 
servo 
relay

B-106

B-121

B-108

3

1

4

2

3

1

32

B-112

B-110

5

78

123

4

2

1

1

R

Fusible link

16

20A

J/B

To engine-ECU

A-08

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TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI) <4G1>

13B-179

FUNCTION

• When the ignition switch ON signal is input into 

the engine-ECU, the engine-ECU turns ON the 
throttle valve control servo.

TROUBLE JUDGMENT

Check Condition

• After engine starts

Judgement Criterions

• Throttle valve control servo supply voltage is less 

than 6.0 V.

• Battery voltage is more than 8.3 V.

PROBALE CAUSES

• Failed throttle valve return spring

• Open/short circuit and damage in throttle valve 

control servo circuit or loose connector contact.

• Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. Connector check: B-121 throttle valve 
control servo relay connector

Q: Is the check result normal?

YES : 

Go to Step 2 .

NO : 

Repair or replace the connector.

STEP 2. Check throttle valve control servo relay 
itself.

• Check throttle valve control servo relay (Refer to 

P.13B-364

).

Q: Is the check result normal?

YES : 

Go to Step 3 .

NO : 

Replace the throttle valve control servo 
relay.

STEP 3. Perform voltage measurement at B-121 
throttle valve control servo relay connector.

• Remove relay, and measure at J/B side.

• Voltage between terminal No. 3 and earth.

OK: System voltage

Q: Is the check result normal?

YES : 

Go to Step 4 .

NO : 

Check intermediate connector B-208, and 

repair if necessary. If intermediate 
connector is normal, Check and repair 
harness between B-121 (terminal No. 3) 
throttle valve control servo relay connector 
and battery.

• Check power supply line for 

open/short circuit.

AK402100

3

2

1

4

AC

Connector: B-121

J/B side 
connector

B-121

AK402100

3

2

1

4

AC

Connector: B-121

J/B side 
connector

B-121

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TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI) <4G1>

13B-180

STEP 4. Perform voltage measurement at B-121 
throttle valve control servo relay connector.

• Remove relay, and measure at J/B side.

• Ignition switch: ON

• Voltage between terminal No. 1 and earth.

OK: System voltage

Q: Is the check result normal?

YES : 

Go to Step 6 .

NO : 

Go to Step 5 .

STEP 5. Connector check: B-106 engine control 
relay connector

AK402100

3

2

1

4

AC

Connector: B-121

J/B side 
connector

B-121

3

2

1

4

AK402084

J/B side 
connector

B-106

Connector: B-106
J/B (front side)

AC

AK402100

3

2

1

4

AC

Connector: B-121

J/B side 
connector

B-121

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