Mitsubishi Galant (2004+). Manual — part 738

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-91

NOTE: Also check joint connectors C-03 for loose, corroded, or
damaged terminals, or terminals pushed back in the connector.
If joint connector C-03 is damaged, repair or replace the con-
nector as described in GROUP 00E, Harness Connector
Inspection

P.00E-2

.

Q: Are the wiring harnesses between A/C-ECU connector

C-15 (terminals 16 and 20), C-16 (terminal 21) and mode
selection damper control motor and potentiometer
connector C-102 (terminals 5, 7 and 3) in good
condition?
YES : Go to Step 6.
NO : Repair the wiring harness. Then go to Step 7.

STEP 6. Check the mode selection damper control motor
and potentiometer.

CAUTION

Do not apply battery voltage when the damper is in the
FACE or DEF position.
(1) Operate the mode selection damper control motor as

described in the table below.

(2) Measure the resistances between connector terminals 3

and 5, and between 3 and 7, while the mode selection
damper control motor is running. The resistances should
change gradually within the standard value.

Standard value: 0.8 (DEF)

− 4.8 (FACE) kΩ

Q: Are the mode selection damper control motor and

potentiometer in good condition?
YES : Repair the A/C-ECU. Then 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

AB

1 2

4

3

5

7

6

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-92

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.

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-93

DTC B1065: Mode Selection Damper Control Motor and Potentiometer

.

DTC SET CONDITION

• If the air mixing damper control motor does not

work normally, DTC B1065 will be set.

.

TECHNICAL DESCRIPTION (COMMENT)

Current trouble

• The A/C-ECU, the mode selection damper con-

trol motor and potentiometer, or connector(s) or
wiring between them may be defective.

Past trouble

• If DTC B1065 is stored as a past trouble, carry

out diagnosis with particular emphasis on wiring
and connector(s) between the A/C-ECU and the
mode selection damper control motor and poten-
tiometer. If the connectors and wiring are normal,
and obviously the ECU is the cause of the trou-
ble, replace the ECU. If in doubt, do not replace
the ECU.

TROUBLESHOOTING HINT

• Malfunction of connector.

• Malfunction of the harness.

• Malfunction of the mode selection damper control

motor and potentiometer.

• Malfunction of the A/C-ECU.

A/C-ECU

MODE SELECTION
DAMPER CONTROL
MOTOR AND
POTENTIOMETER

MOTOR
DRIVE
CIRCUIT

Mode Selection Damper Control Motor Circuit

AC305233

C-15 (B)

BI

CONNECTOR: C-15

AC305231

C-102

CF

CONNECTOR: C-102

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-94

DIAGNOSIS

Required Special Tool:

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

• MB991824: Vehicle Communication Interface (V.C.I.)

• MB991827: MUT-III USB Cable

• MB991910: MUT-III Main Harness A (Vehicles with CAN

communication system)

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

Use scan tool MB991958 to diagnose the CAN bus lines.
(1) Connect scan tool MB991958 to the data link connector.
(2) Turn the ignition switch to "ON" position.

(3) Diagnose the CAN bus line.
Q: Is the check result satisfactory?

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

Diagnosis-Can Bus Diagnostic Chart

P.54C-621

).

Then go to Step 7.

STEP 2. Recheck for diagnostic trouble code.

Recheck if the DTC is set.

1. Erase the DTC.
2. Turn the ignition switch to "ON" position.
3. Check if the DTC is set.

Q: Is the check result satisfactory?

YES : It can be assumed that this malfunction is intermittent.

Refer to GROUP 00, How to Use
Troubleshooting/Inspection Service Points

− How to

Use Troubleshooting/Inspection Service Points

P.00-6

.

NO : Go to Step 3.

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827