Mitsubishi 380. Manual — part 189

AUTO A/C DIAGNOSIS

HEATER, AIR CONDITIONING AND VENTILATION

55-52

STEP 6. Check the mode selection damper control motor.

CAUTION

Do not apply battery voltage when the damper is in the
FACE or DEF position.
Check the mode selection damper control motor by the follow-
ing procedures.

Q: Is the mode selection damper control motor in good

condition?
YES : Go to Step 7.
NO : Replace the mode selection damper control motor

and potentiometer. Then go to Step 7.

LEVER POSITION BATTERY

CONNECTION

LEVER
OPERATION

At the FACE
position

• Connect

terminal 2 to the
positive battery
terminal

• Connect

terminal 1 to the
negative battery
terminal

The lever moves
from the FACE
position to the DEF
position

At the DEF position

• Connect

terminal 1 to the
positive battery
terminal

• Connect

terminal 2 to the
negative battery
terminal

The lever moves
from the DEF
position to the
FACE position

25DB066A

FACE POSITION

DEF POSITION

1 2

4

3

5

7

6

AUTO A/C DIAGNOSIS

HEATER, AIR CONDITIONING AND VENTILATION

55-53

STEP 7. Recheck for diagnostic trouble code.
Check again if the DTC is set.
(1) Connect diagnostic tool 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 : The procedure is complete.
NO : Return to Step 1.

00DB076A

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

AUTO A/C DIAGNOSIS

HEATER, AIR CONDITIONING AND VENTILATION

55-54

DTC U1073: Bus Off

CAUTION

If DTC U1073 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

DTC U1073 will be stored when the A/C-ECU ceases
CAN communication (bus off) and then resumes the
communication when the ignition switch is turned to
the "LOCK" (OFF) position.

.

TECHNICAL DESCRIPTION (COMMENT)

The wiring harness wire or connectors may have
loose, corroded, or damage terminals, or terminals
pushed back in the connector, or the A/C-ECU may
be defective.

.

TROUBLESHOOTING HINTS

• Defective connector(s) or wiring harness

• Malfunction of the A/C-ECU.

• Refer to component locations GROUP-

70

• Refer to configuration diagrams GROUP-

80

• Refer to circuit diagrams GROUP-

90

DIAGNOSIS

Required Special Tools:

• MB991223: Harness Set

• : Diagnostic Tool (MUT-III Sub Assembly)

• MB991824: V.C.I.

• MB991827: USB Cable

• MB991910: Main Harness A

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 lines (Refer to GROUP 54C,

precautions on how to repair the can bus lines

P.54C-5

).

00DB076A

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

AUTO A/C DIAGNOSIS

HEATER, AIR CONDITIONING AND VENTILATION

55-55

STEP 2. Recheck for diagnostic trouble code.
Check again if the DTC is set.
(1) Connect diagnostic tool 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

− How to Cope with Intermittent

Malfunctions

P.00-14

.)

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

DTC is not reset.

00DB076A

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827