Mitsubishi Galant 9G. Manual — part 236

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-20

STEP 3. Using scan tool MB991958, check data list item 03:
air thermo sensor.

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) Ignition switch: ON
(3) Set scan tool MB991958 to the data reading mode for item

03: air thermo sensor.

• Check that the passenger room temperature matches

the displayed value on the scan tool while the engine is
cold.

NOTE: When this DTC is set and the system is fail-safe sta-
tus, the value of service data displays

−

6

°

C.

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the sensor within the specified range?

YES : Replace the A/C-ECU. Then go to Step 7.
NO : Go to Step 4.

STEP 4. Check A/C-ECU connector C-10 and air thermo
sensor connector C-126 for loose, corroded or damaged
terminals, or terminals pushed back in the connector.
Q: Are A/C-ECU connector C-10 and air thermo sensor

connector C-126 in good condition?
YES : Go to Step 5.
NO : Repair or replace the connector. Refer to GROUP

00E, Harness Connector Inspection

P.00E-2

. Then go

to Step 7.

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

AC305231

CONNECTOR: C-126

CB

HARNESS SIDE

AC305233AW

CONNECTOR: C-10

HARNESS SIDE

C-10 (B)

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-21

STEP 5. Check the wiring harness between A/C-ECU
connector C-10 (terminal 10 and 13) and air thermo sensor
connector C-126 (terminals 2 and 1).

NOTE: Also check joint connector 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: Is the wiring harness between A/C-ECU connector C-10

(terminal 10 and 13) and air thermo sensor connector
C-126 (terminals 2 and 1) in good condition?
YES : Go to Step 6.
NO : Repair the wiring harness. Then go to Step 7.

AC305233AW

CONNECTOR: C-10

HARNESS SIDE

C-10 (B)

AC305232

C-03

C-126

C-03

HARNESS SIDE

C-126

AP

CONNECTORS: C-03, C-126

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-22

STEP 6. Check the air thermo sensor.
(1) Disconnect the air thermo sensor connector C-126.

(2) Measure the resistance between connector terminals 1 and

2 under at least two different temperatures. The resistance
values should generally match those in the graph.
NOTE: The temperature at the check should not exceed the
range in the graph.

Q: Is the air thermo sensor in good condition?

YES : Replace the A/C-ECU. Then go to Step 7.
NO : Replace the air thermo sensor. Then go to Step 7.

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.

AC305231

CONNECTOR: C-126

CB

HARNESS SIDE

AC001043

RESISTANCE k

Ω

8

6

4

2

0

-10

0

10

20

30

40

TEMPERATURE ˚C(˚F)

AB

(14)

(32)

(50)

(86)

(104)

(68)

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-23

DTC B1041, B1042: Air Mixing Damper Control Motor and Potentiometer (Potentiometer system)

.

DTC SET CONDITION

• DTC B1041 or B1042 is set if there is an open or

short circuit in the potentiometer input circuit, or if
there is an open circuit in the power circuit or
earth circuit.

.

TECHNICAL DESCRIPTION (COMMENT)

Current trouble

• The A/C-ECU, the air mixing damper control

motor and potentiometer, or connector(s) or wir-
ing between the two may be defective.

Past trouble

• If DTC B1041 or B1042 is stored as a past trou-

ble, carry out diagnosis with particular emphasis
on wiring and connector(s) between the A/C-ECU
and the air mixing damper control motor and
potentiometer. If the connectors and wiring are
normal, and obviously the ECU is the cause of
the trouble, replace the ECU. If in doubt, do not
replace the ECU.

TROUBLESHOOTING HINT

• Malfunction of connector.

• Malfunction of the harness.

• Malfunction of the air mixing damper control

motor and potentiometer.

• Malfunction of the A/C-ECU.

AIR MIXING
DAMPER CONTROL
MOTOR AND
POTENTIOMETER

JOINT
CONNECTOR (2)

A/C-ECU

Air Mixing Damper Control Motor Potentiometer

AC305231AZ

CONNECTOR: C-03

AC305233

CONNECTOR: C-10, C-105

AZ

C-105

C-10 (B)