Mitsubishi Galant (2004+). Manual - part 1120

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-173

STEP 8. Using scan tool MB991958, read the diagnostic
trouble code (DTC).

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) After the DTC has been deleted, read the DTC again.
(4) Turn the ignition switch to the "LOCK"(OFF) position.
Q: Is DTC P0123 set?

YES : Retry the troubleshooting.
NO : The inspection is complete.

AC305412

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-174

TCLDTC P0125: Insufficient Coolant Temperature for Closed Loop Fuel Control

CAUTION

If DTC P0125 has been set, TCL related DTC
U1120 is also set. After P0125 has been diag-
nosed, don't forget to erase DTC U1120.

YELLO

-GREEN

BLA

AK302836

ENGINE COOLANT
TEMPERATURE SENSOR

POWERTRAIN CONTROL MODULE(PCM)

5 V

B-104

(MU802406)

Engine Coolant Temperature Sensor Circuit

1 2

B-21

B-22

53 54 55 56

58 59 60 61 62

64 65 66 67 68 69

71 72 73 74 75

77 78 79 80 81 82

100

93 94 95

96 97 98

101 102 103 104

105 106 107 108

109 110 111 112 113

AK303036

CONNECTOR: B-104

B-104 (B)

ENGINE
COOLANT
TEMPERATURE
SENSOR

THROTTLE
BODY

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-175

CIRCUIT OPERATION

• 5-volt voltage is applied to the engine coolant

temperature sensor output terminal (terminal No.
1) from the PCM (terminal No. 93) via the resistor
in the PCM. The ground terminal (terminal No. 2)
is grounded with PCM (terminal No. 69).

• 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 volt-

age drops from over 40

°C (104°F) to under 40°C

(104

°F) and keeps under 40°C (104°F) for 5 min-

utes.

• Engine coolant temperature sensor output volt-

age does not reach close loop enable tempera-
ture within specified period when engine coolant
temperature sensor output voltage at engine start
is under 7

°C (45°F).

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)

• Mass volume airflow sensor

• Engine coolant temperature sensor

• Intake air temperature sensor

AK303013

CONNECTORS: B-21, B-22

PCM

AIR CLEANER

B-22 (B)

B-21 (B)

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-176

DTC SET CONDITIONS <Range/Performance problem - low input (time to reach closed loop
temperature)>

Logic Flow Chart

Check Conditions, Judgement Criteria

• About 60 − 300 seconds have passed for the

engine coolant temperature to rise to about 7

°C

(44.6

°F) after starting sequence was completed.

• However, time is not counted when fuel is shut

off.

START

END

YES

MALFUNCTION

GOOD

TIME HAVE PASSED

AFTER STARTING?*

ENGINE
COOLANT
TEMP.

TEMP. WHERE
CLOSED LOOP
STARTS

MONITORING

CONDITIONS?

YES

*: SEE DTC SET CONDITIONS-SET CONDITIONS, JUDGMENT CRITERIA

AK302385

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