ECU MITSUBISHI 380 2005 Workshop Manual

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-46
STEP 6. Check the mode selection damper control motor
and potentiometer.
Do not apply battery voltage when the damper is in the
FACE or DEF position.
(1) Operate the mode selection damper control motor as
described in the table below.
(2) Measure the resistances between connector terminals 3
and 5, and between 3 and 7, while the mode selection
damper control motor is running. The resistances should
change gradually within the standard value.
Standard value: 0.8 (DEF)
4.8 (FACE) k
Q: Are the mode selection damper control motor and
potentiometer in good condition?
YES : Replace the A/C-ECU. Then 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 VENTILATION55-48
DTC B1065: Mode Selection Damper Control Motor and Potentiometer
.
DTC SET CONDITION
If the air mixing damper control motor does not
work normally, DTC B1065 will be set.
.
TECHNICAL DESCRIPTION (COMMENT)
Current trouble
The A/C-ECU, the mode selection damper con-
trol motor and potentiometer, or connector(s) or
wiring between them may be defective.Past trouble
If DTC B1065 is stored as a past trouble, carry
out diagnosis with particular emphasis on wiring
and connector(s) between the A/C-ECU and the
mode selection damper control motor and poten-
tiometer. If the connectors and wiring are normal,
and obviously the ECU is the cause of the trou-
ble, replace the ECU. If in doubt, do not replace
the ECU.
TROUBLESHOOTING HINT
Malfunction of connector.
Malfunction of the harness.
Malfunction of the mode selection damper control
motor and potentiometer.
Malfunction of the A/C-ECU.
Refer to component locations GROUP-70
Refer to configuration diagrams GROUP-80
Refer to circuit diagrams GROUP-90

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-50
STEP 3. Using diagnostic tool , check actuator test item 67,
68, 69, 70, 71: Air outlet c/o dumper.
To prevent damage to diagnostic tool , always turn the
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting diagnostic tool .
(1) Connect diagnostic tool to the data link connector.
(2) Start the engine.
(3) Use diagnostic tool to run the actuator test.
Item 67: air mix damper motor (Bi LEVEL position)
Item 68: air mix damper motor (DEF position)
Item 69: air mix damper motor (DEF/FOOT position)
Item 70: air mix damper motor (FACE position)
Item 71: air mix damper motor (FOOT position)
Check that the mode selection damper control motor
operates.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the sensor within the specified range?
YES : Replace the A/C-ECU. Then go to Step 7.
NO : Go to Step 4.
STEP 4. Check A/C-ECU connector C-15 and mode
selection damper control motor and potentiometer
connector C-102 for loose, corroded or damaged
terminals, or terminals pushed back in the connector.
Q: Are A/C-ECU connector C-15 and mode selection
damper control motor and potentiometer connector
C-102 in good condition?
YES : Go to Step 5.
NO : Repair or replace the connector. Refer to GROUP
00E, Harness Connector Inspection P.00E-2. Then go
to Step 7.

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-51
STEP 5. Check the wiring harness between A/C-ECU
connector C-15 (terminals 11 and 4) and mode selection
damper control motor and potentiometer connector C-102
(terminals 1 and 2).
Q: Are the wiring harnesses between A/C-ECU connector
C-15 (terminals 11 and 4) and mode selection damper
control motor and potentiometer connector C-102
(terminals 1 and 2) in good condition?
YES : Go to Step 6.
NO : Repair the wiring harness. Then go to Step 7.

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 VENTILATION55-58
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.

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-60
DTC U1111: Multi-Center Display Unit Time-out
If DTC U1111 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 signals from the multi-center
display unit. If the ECU cannot receive the signal
r e l a t e d t o t h e m u l t i - c e n t e r d i s p l a y u n i t , D T C U 1111
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
W h e n D T C U 1111 i s s e t a s a p a s t t r o u b l e , c a r r y
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)