Mitsubishi Galant (2004+). Manual - part 730

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-59

DIAGNOSTIC TROUBLE CODE CHART <MIDDLE TYPE>

M1554004900214

CAUTION

During diagnosis, a DTC code associated with 
other system may be set when the ignition switch 
is turned on with connector(s) disconnected. On 
completion of repairs, confirm all systems for 
DTC code(s). If DTC code(s) are set, erase them 
all.

DIAGNOSTIC 
TROUBLE CODE 
NO.

DIAGNOSTIC ITEM

REFERENCE 
PAGE

B1011

Ambient air temperature sensor system (short circuit)

P.55A-60

B1012

Ambient air temperature sensor system (open circuit)

P.55A-60

B1021

Air thermo sensor system (short circuit)

P.55A-67

B1022

Air thermo sensor system (open circuit)

P.55A-67

B1041

Air mixing damper control motor and potentiometer (potentiometer 
system shorted to its power supply)

P.55A-74

B1042

Air mixing damper control motor and potentiometer (potentiometer 
system shorted to its ground)

P.55A-74

B1045

Air mixing damper control motor and potentiometer (activating 
system failure)

P.55A-80

B1061

Mode selection damper control motor and potentiometer 
(potentiometer system shorted to its power supply)

P.55A-86

B1062

Mode selection damper control motor and potentiometer 
(potentiometer system shorted to its ground)

P.55A-86

B1065

Mode selection damper control motor and potentiometer (activating 
system failure)

P.55A-93

U1073

Bus off

P.55A-98

U1100

Powertrain control module time-out (related to engine)

P.55A-100

U1111

Multi-center display unit (middle grade type) time-out

P.55A-104

U1120

Failure information on powertrain control module (related to engine)

P.55A-108

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-60

DIAGNOSTIC TROUBLE CODE PROCEDURES <MIDDLE TYPE>

DTC B1011, B1012: Ambient Air Temperature Sensor System

CAUTION

If DTC B1011 or B1012 has been set, multi-dis-
play related DTC U1130 is also set. After B1011 or 
B1012 has been diagnosed, don't forget to erase 
DTC U1130.

AMBIENT AIR
TEMPERATURE
SENSOR

JOINT
CONNECTOR (2)

A/C-ECU

Ambient Temperature Sensor Circuit

AC305210

A-25 (BR)

AQ

CONNECTOR: A-25

AC305233

C-16 (B)

C-23

CONNECTORS: C-15, C-16,C-23

C-15 (B)

BD

MANUAL A/C DIAGNOSIS

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HEATER, AIR CONDITIONING AND VENTILATION

55A-61

.

DTC SET CONDITION

• DTC B1011 is set if there is a short circuit in the 

ambient air temperature sensor input circuit.

• DTC B1012 is set if there is a defective connector 

connection, or if there is an open circuit in the 
harness.

.

TECHNICAL DESCRIPTION (COMMENT)

Current trouble

• The A/C-ECU, the ambient air temperature sen-

sor, or connector(s) or wiring between the two 
may be defective.

Past trouble

• If DTC B1011 or B1012 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 ambient air temperature sensor. 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 ambient air temperature sen-

sor.

• Malfunction of the A/C-ECU.

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)

AC305231AZ

CONNECTOR: C-03

MANUAL A/C DIAGNOSIS

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HEATER, AIR CONDITIONING AND VENTILATION

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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. Repair the CAN bus lines 

(Refer to GROUP 54C, Diagnosis-Can Bus 
Diagnostic Chart 

P.54C-621

). Then go to Step 8.

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