Mitsubishi Outlander GS45X. Manual - part 1005

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-47

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 : A poor connection, open circuit or other intermittent 

malfunction is present in the lines between the 
EATCS-ECU and the A/C-ECU (Refer to GROUP 
00E, Harness Connector Inspection 

P.00E-2

.)

NO :   Replace the ETACS-ECU. On completion, check that 

the DTC is not reset.

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 
ETACS-ECU and the A/C-ECU (Refer to GROUP 
00E, Harness Connector Inspection 

P.00E-2

.)

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

DTC is not reset.

DTC U0151: SRS-ECU Time-out

CAUTION

If DTC U0151 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 air conditioning opera-
tion-related signals from the SRS-ECU via the CAN 
bus lines. If any of the air conditioning control-related 
signals from the SRS-ECU cannot be received, the 
diagnostic trouble code U0151 is stored.

.

TECHNICAL DESCRIPTION (COMMENT) 

Current trouble

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

lines between the SRS-ECU and the A/C-ECU, 
the power supply system to the SRS-ECU, the 
SRS-ECU itself, or the A/C-ECU may be defec-
tive.

Past trouble

• If DTC U0151 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 SRS-ECU, and the power 
supply system to the SRS-ECU. 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 

−

 How to Cope with Intermit-

tent Malfunctions 

P.00-15

) 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-16

).

.

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-48

TROUBLESHOOTING HINTS

• Malfunction of the SRS-ECU

• Malfunction of the A/C-ECU

• Damaged harness wires and connectors

DIAGNOSIS

Required Special Tools:

• MB991223: Harness Set

• MB992006: Extra Fine Probe

•  MB991958: Scan Tool (M.U.T.-III Sub Assembly)

• MB991824: V.C.I.

• MB991827: M.U.T.-III USB Cable

• MB991910: M.U.T.-III Main Harness A

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

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. Refer to "How to connect the 

Scan Tool (M.U.T.-III) 

P.55A-7

."

(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-17

).

STEP 2. Using scan tool MB991958 read the SRS-ECU 
diagnostic trouble code.
Check whether an SRS-ECU DTCs are set or not.
(1) Turn the ignition switch to the "ON" position.
(2) Check for SRS-ECU DTCs.
(3) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the check result satisfactory?

YES :  Go to Step 3.
NO :   Diagnose the SRS-ECU (Refer to GROUP 52B, 

Diagnostic Trouble Code 

P.52B-31

).

ZC501967

AC404789

AC701411AB

MB991824

MB991827

MB991910

Data link 
connector

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-49

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.

• ETACS-ECU

DTC indicating a time-out error related to the SRS-ECU 
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 : A poor connection, open circuit or other intermittent 

malfunction is present in the lines between the 
SRS-ECU and the A/C-ECU (Refer to GROUP 00E, 
Harness Connector Inspection 

P.00E-2

.)

NO :   Replace the SRS-ECU. On completion, check that 

the DTC is not reset.

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 
SRS-ECU and the A/C-ECU (Refer to GROUP 00E, 
Harness Connector Inspection 

P.00E-2

.)

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

DTC is not reset.

DTC U0154: Occupant classification-ECU Time-out

CAUTION

If DTC U0154 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 the air conditioning con-
trol-related signals from the occupant classifica-
tion-ECU via the CAN bus lines. If any of the air 
conditioning control-related signals from the occu-
pant classification-ECU cannot be received, the diag-
nostic trouble code U0154 is stored.

.

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-50

TECHNICAL DESCRIPTION (COMMENT) 

Current trouble

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

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

Past trouble

• If DTC U0154 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 Occupant classifica-
tion-ECU, and the power supply system to the 
Occupant classification-ECU. 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 

−

 How to Cope with Intermit-

tent Malfunctions 

P.00-15

) 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-16

).

.

TROUBLESHOOTING HINTS

• Malfunction of the Occupant classification-ECU

• Malfunction of the A/C-ECU

• Damaged harness wires and connectors

DIAGNOSIS

Required Special Tools:

• MB991223: Harness Set

• MB992006: Extra Fine Probe

•  MB991958: Scan Tool (M.U.T.-III Sub Assembly)

• MB991824: V.C.I.

• MB991827: M.U.T.-III USB Cable

• MB991910: M.U.T.-III Main Harness A

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

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. Refer to "How to connect the 

Scan Tool (M.U.T.-III) 

P.55A-7

."

(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-17

).

ZC501967

AC404789

AC701411AB

MB991824

MB991827

MB991910

Data link 
connector