Mitsubishi Galant 9G. Manual - part 242

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-44

STEP 5. Check the wiring harness between A/C-ECU
connector C-09 (terminals 31 and 30) and mode selection
damper control motor and potentiometer connector C-102
(terminals 1 and 2).
Q: Are the wiring harnesses between A/C-ECU connector

C-09 (terminals 31 and 30) and mode selection damper
control motor and potentiometer connector C-102
(terminals 1 and 2) in good condition?
YES : Go to Step 6.
NO : Repair the wiring harness. Then go to Step 7.

AC305233

C-09 (B)

HARNESS SIDE

CONNECTOR: C-09

AC305231

C-102

HARNESS SIDE

CONNECTOR: C-102

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-45

STEP 6. Check the mode selection damper control motor.

CAUTION

Do not apply battery voltage when the damper is in the
FACE or DEF position.
Check the mode selection damper control motor by the follow-
ing procedures.

Q: Is the mode selection damper control motor in good

condition?
YES : Go to Step 7.
NO : Replace the mode selection damper control motor

and potentiometer. Then go to Step 7.

LEVER POSITION BATTERY

CONNECTION

LEVER
OPERATION

At the FACE
position

• Connect

terminal 2 to the
positive battery
terminal

• Connect

terminal 1 to the
negative battery
terminal

The lever moves
from the FACE
position to the DEF
position

At the DEF position

• Connect

terminal 1 to the
positive battery
terminal

• Connect

terminal 2 to the
negative battery
terminal

The lever moves
from the DEF
position to the
FACE position

AC209789

FACE POSITION

DEF POSITION

1 2

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-46

STEP 7. Recheck for diagnostic trouble code.
Check again if the DTC is set.
(1) Connect scan tool MB991958 to the data link connector
(2) Turn the ignition switch to the "ON" position.
(3) Check if the DTC is set.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the check result satisfactory?

YES : The procedure is complete.
NO : Return to Step 1.

DTC U1073: Bus Off

CAUTION

If DTC U1073 is set in the A/C-ECU, diagnose the
CAN main bus line.

CAUTION

Whenever the ECU is replaced, ensure that the
communication circuit is normal.

TROUBLE JUDGMENT

DTC U1073 will be stored when the A/C-ECU ceases
CAN communication (bus off) and then resumes the
communication when the ignition switch is turned to
the "LOCK" (OFF) position.

TECHNICAL DESCRIPTION (COMMENT)

The wiring harness wire or connectors may have
loose, corroded, or damage terminals, or terminals
pushed back in the connector, or the A/C-ECU may
be defective.

TROUBLESHOOTING HINTS

• Defective connector(s) or wiring harness

• Malfunction of the A/C-ECU

DIAGNOSIS

Required Special Tools:

• MB991223: Harness Set

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

• MB991824: V.C.I.

• MB991827: USB Cable

• MB991910: Main Harness A

AC305412

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-47

STEP 1. Using scan tool MB991958, diagnose the CAN bus
line.

CAUTION

To prevent damage to scan tool (MUT-III), always turn the
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting scan tool (MUT-III).
(1) Connect scan tool MB991958 to the data link connector.
(2) Turn the ignition switch to the "ON" position.
(3) Diagnose the CAN bus line.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the CAN bus line found to be normal?

YES : Go to Step 2.
NO : Repair the CAN bus lines (Refer to GROUP 54C,

precautions on how to repair the can bus lines

P.54C-5

STEP 2. Recheck for diagnostic trouble code.
Check again if the DTC is set.
(1) Connect scan tool MB991958 to the data link connector
(2) Turn the ignition switch to the "ON" position.
(3) Check if the DTC is set.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the check result satisfactory?

YES : There is an intermittent malfunction such as poor

engaged connector(s) or open circuit (Refer to
GROUP 00, How to Use Troubleshooting/Inspection
Service Points

− How to Cope with Intermittent

Malfunctions

P.00-14

NO : Replace the A/C-ECU. On completion, check that the

DTC is not reset.

AC305412

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

AC305412

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

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