2005 MITSUBISHI 380 Workshop Manual

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-52
STEP 6. Check the mode selection damper control motor.
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
CONNECTIONLEVER
OPERATION
At the FACE
position
Connect
terminal 2 to the
positive battery
terminal
Connect
terminal 1 to the
negative battery
terminalThe 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
terminalThe lever moves
from the DEF
position to the
FACE position

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-53
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.

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-54
DTC U1073: Bus Off
If DTC U1073 is set in the A/C-ECU, diagnose the
CAN main bus line.
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.
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).

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-55
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.

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-56
DTC U1100: Electronic control unit Time-out (Related to Engine)
If DTC U1100 is set in the A/C-ECU, diagnose the
CAN main bus line.
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 Electronic control unit. 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 Electronic control unit and the
A/C-ECU, the power supply system to the
Electronic control unit, the Electronic control unit
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 Electronic control unit, and
the power supply system to the Electronic control
unit. 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 diagnostic tool CAN bus diagnostics even if
there is a failure in CAN bus lines. In this case,
refer to GROUP 00, How to Use Troubleshoot-
ing/Inspection Service Points
How to Cope with
Intermittent Malfunctions P.00-14) and check the
CAN bus lines. You can narrow down the possi-
ble 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
Electronic control unit failed
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 VENTILATION55-57
STEP 1. Using diagnostic tool , diagnose the CAN bus line.
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).
STEP 2. Using diagnostic tool read the Electronic control
unit 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 : Go to Step 3.
NO : Diagnose the Electronic control unit (Refer to
GROUP 13A, Diagnostic Trouble Code 13A-17 ).

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-58
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.
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.
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
Electronic control unit and the A/C-ECU (Refer to
GROUP 00E, Harness Connector Inspection
P.00E-2.)
NO : Replace the Electronic control unit. On completion,
check that the DTC is not reset.

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-59
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
Electronic control unit 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.