Mitsubishi Galant 9G. Manual - part 245

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-56

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 line (Refer to GROUP 54C,

Diagnosis

P.54C-14

STEP 2. Using scan tool MB991958, read the powertrain
control module diagnostic trouble code.
Check whether any engine or automatic transmission DTCs are
set or not.
(1) Turn the ignition switch to the "ON" position.
(2) Check for engine and automatic transmission DTCs.
(3) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the check result satisfactory?

YES : Go to Step 3.
NO : Refer to GROUP 13A, Diagnostic Trouble Code

P.13A-33

<2.4L> or GROUP 13B, Diagnostic Trouble

Code

P.13B-34

<3.8L>.

AC305412

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

AC305412

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-57

STEP 3. Using scan tool MB991958, check for any
diagnostic trouble code.
Check if a DTC, which relates to CAN communication-linked
systems below, is set.

• Combination meter

DTC indicating a time-out error related to the engine or
automatic transmission control system

• ETACS

DTC indicating a time-out error related to the engine or
automatic transmission control system

• Multi-center display unit (middle grade type)

DTC indicating a time-out error related to the engine or
automatic transmission control system

(1) Turn the ignition switch to the "ON" position.
(2) Check for a DTC related to the relevant system.
(3) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the check result satisfactory?

YES : Go to Step 5.
NO : Go to Step 4.

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

YES : Replace the powertrain control module. On

completion, check that the DTC is not reset.

NO : 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

AC305412

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

AC305412

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

MANUAL A/C DIAGNOSIS

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HEATER, AIR CONDITIONING AND VENTILATION

55A-58

STEP 5. Recheck for diagnostic trouble code.
Check again if the DTC is set.
(1) Turn the ignition switch to the "ON" position.
(2) Check if the DTC is set.
(3) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the check result satisfactory?

YES : A poor connection, open circuit or other intermittent

malfunction is present in the lines between the
powertrain control module and the A/C-ECU (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.

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.

AC305412

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

DIAGNOSTIC
TROUBLE CODE
NO.

DIAGNOSTIC ITEM

REFERENCE
PAGE

B1011

Ambient air temperature sensor system (short circuit)

P.55A-59

B1012

Ambient air temperature sensor system (open circuit)

P.55A-59

B1021

Air thermo sensor system (short circuit)

P.55A-65

B1022

Air thermo sensor system (open circuit)

P.55A-65

B1041

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

P.55A-72

B1042

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

P.55A-72

B1045

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

P.55A-78

B1061

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

P.55A-84

B1062

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

P.55A-84

MANUAL A/C DIAGNOSIS

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HEATER, AIR CONDITIONING AND VENTILATION

55A-59

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.

B1065

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

P.55A-91

U1073

Bus off

P.55A-97

U1100

Powertrain control module time-out (related to engine)

P.55A-99

U1111

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

P.55A-102