Mitsubishi 380. Manual - part 191

AUTO A/C DIAGNOSIS

HEATER, AIR CONDITIONING AND VENTILATION

55-60

DTC U1111: Multi-Center Display Unit Time-out

CAUTION

If DTC U1111 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 signals from the multi-center 
display unit. If the ECU cannot receive the signal 
related to the multi-center display unit, DTC U1111 
will be set.

.

TECHNICAL DESCRIPTION (COMMENT) 

Current trouble

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

lines between the A/C-ECU and the multi-center 
display unit, the power supply system to the dis-
play unit, the display unit itself, or the A/C-ECU 
may be defective.

Past trouble

• When DTC U1111 is set as a past trouble, carry 

out diagnosis with particular emphasis on con-
nector(s) or wiring harness in the CAN bus lines 
between the A/C-ECU and the multi-center dis-
play unit, the power supply system to the display 

unit. If the connectors and wiring are normal, and 
obviously the ECU or the multi-center display is 
the cause of the trouble, replace the ECU or the 
multi-center display. If in doubt, do not replace 
the ECU or the display unit.

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

− How to 

Cope with Intermittent Malfunctions 

P.00-14

.) 

and check the CAN bus lines. You can narrow 
down the possible cause of the trouble by refer-
ring to the DTC, which is set regarding the CAN 
communication-linked ECUs (Refer to GROUP 
54C 

− Explanation about the diagnostic tool CAN 

bus diagnostics 

P.54C-6

).

.

TROUBLESHOOTING HINTS

• Malfunction of multi-center display unit

• Malfunction of the A/C-ECU

• Damaged harness wires and connectors

• Refer to component locations GROUP-

70

• Refer to configuration diagrams GROUP-

80

• Refer to circuit diagrams GROUP-

90

DIAGNOSIS

Required Special Tools:

•  : Diagnostic 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)

AUTO A/C DIAGNOSIS

HEATER, AIR CONDITIONING AND VENTILATION

55-61

STEP 1. Using diagnostic tool , diagnose the CAN bus line.

CAUTION

To prevent damage to diagnostic tool (MUT-III), always turn 
the ignition switch to the "LOCK" (OFF) position before 
connecting or disconnecting diagnostic tool (MUT-III).
(1) Connect diagnostic tool  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-15

).

STEP 2. Using diagnostic tool , read the Electronic control 
unit diagnostic trouble code.
Check that the multi-center display unit sets a DTC.
(1) Turn the ignition switch to the "ON" position.
(2) Check for the DTC related to the multi-center display unit.
(3) Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the check result satisfactory?

YES : Refer to GROUP 54A, multi-center display unit 

− 

Diagnosis 

P.54A-254

.

NO :  Go to Step 3.

00DB076A

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

00DB076A

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

AUTO A/C DIAGNOSIS

HEATER, AIR CONDITIONING AND VENTILATION

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STEP 3. Using diagnostic tool , 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 of multi-center display unit

(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 4.
NO :  Go to Step 5.

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 multi-center display unit. On completion, 

check that the DTC is not reset.

NO :  A poor connection, open circuit or other intermittent 

malfunction is present in the CAN bus lines between 
the multi-center display unit 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

).

00DB076A

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

00DB076A

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

AUTO A/C DIAGNOSIS

HEATER, AIR CONDITIONING AND VENTILATION

55-63

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 : Replace the A/C-ECU. On completion, check that the 

DTC is not reset.

NO :  A poor connection, open circuit or other intermittent 

malfunction is present in the CAN bus lines between 
the multi-center display unit 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

).

00DB076A

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827