Mitsubishi Galant (2004+). Manual - part 740

 

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Mitsubishi Galant (2004+). Manual - part 740

 

 

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-99

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

P.00-6

.)

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

DTC is not reset.

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-100

DTC U1100: Powertrain Control Module Time-out (Related to Engine)

CAUTION

If DTC U1100 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
The A/C-ECU receives engine control sys-
tem-related signal from the powertrain control mod-
ule. If the ECU cannot receive the signal, DTC 
U1100 will be set.

.

TECHNICAL DESCRIPTION (COMMENT) 

Current trouble

• Connector(s) or wiring harness in the CAN bus 

lines between the powertrain control module and 
the A/C-ECU, the power supply system to the 
powertrain control module, the powertrain control 
module itself, or the A/C-ECU may be defective.

Past trouble

• If DTC U1100 is stored as a past trouble, carry 

out diagnosis with particular emphasis on wiring 
and connector(s) in the CAN bus line between 
the A/C-ECU and the powertrain control module, 
and the power supply system to the powertrain 
control module. 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.

NOTE: For a past trouble, you cannot find it by 
the scan tool CAN bus diagnostics even if there is 
a failure in CAN bus lines. In this case, refer to 
GROUP 00, How to Use Troubleshooting/Inspec-
tion Service Points 

P.00-6

) and check the CAN 

bus lines. You can narrow down the possible 
cause of the trouble by referring to the DTC, 
which is set regarding the CAN communica-
tion-linked ECUs (Refer to GROUP 54C, Expla-
nation about the scan too CAN bus diagnostics 

P.54C-6

).

.

TROUBLESHOOTING HINTS

• Powertrain control module failed

• Malfunction of the A/C-ECU

• Damaged harness wires and connectors

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-101

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.

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

).

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-102

STEP 2. Using scan tool MB991958 read the powertrain 
control module diagnostic trouble code.

Check whether an engine and 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 :  Diagnose the powertrain control module (Refer to 

GROUP 13A, Diagnostic Trouble Code 

P.13A-34

 

<2.4L> or GROUP 13B, Diagnostic Trouble Code 

P.13B-33

 <3.8L>).

NO :   Go to Step 3.

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-ECU

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.

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

 

 

 

 

 

 

 

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