2005 MITSUBISHI 380 GROUP-90

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-22
DTC B1021, B1022: Air Thermo Sensor System
.
DTC SET CONDITION
DTC B1021 is set if there is a short circuit in the
air thermo sensor input circuit.
DTC B1022 is set if there is a defective connector
connection, or if there is an open circuit in the
harness.
.
TECHNICAL DESCRIPTION (COMMENT)
Current trouble
The A/C-ECU, the air thermo sensor, or connec-
tor(s) or wiring between the two may be defec-
tive.Past trouble
If DTC B1021 or B1022 is stored as a past trou-
ble, carry out diagnosis with particular emphasis
on wiring and connector(s) between the A/C-ECU
and the air thermo sensor. 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.
TROUBLESHOOTING HINT
Malfunction of connector.
Malfunction of the harness.
Malfunction of the air thermo sensor.
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 VENTILATION55-28
DTC B1041, B1042: Air Mixing Damper Control Motor and Potentiometer (Potentiometer system)
.
DTC SET CONDITION
DTC B1041 or B1042 is set if there is an open or
short circuit in the potentiometer input circuit, or if
there is an open circuit in the power circuit or
earth circuit.
.
TECHNICAL DESCRIPTION (COMMENT)
Current trouble
The A/C-ECU, the air mixing damper control
motor and potentiometer, or connector(s) or wir-
ing between the two may be defective.Past trouble
If DTC B1041 or B1042 is stored as a past trou-
ble, carry out diagnosis with particular emphasis
on wiring and connector(s) between the A/C-ECU
and the air mixing damper control motor and
potentiometer. 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.
TROUBLESHOOTING HINT
Malfunction of connector.
Malfunction of the harness.
Malfunction of the air mixing 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
DIAGNOSIS
Required Special Tool:
: 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 VENTILATION55-35
DTC B1045: Air mixing damper control motor and potentiometer (activating system failure)
.
DTC SET CONDITION
If the air mixing damper control motor does not
work normally, DTC No.B1045 will be set.
.
TECHNICAL DESCRIPTION (COMMENT)
Current trouble
The A/C-ECU, the air mixing damper control
motor and potentiometer, or connector(s) or wir-
ing between the two may be defective.Past trouble
If DTC B1045 is stored as a past trouble, carry
out diagnosis with particular emphasis on wiring
and connector(s) between the A/C-ECU and the
air mixing damper control motor and potentiome-
ter. 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.
TROUBLESHOOTING HINT
Malfunction of connector.
Malfunction of the harness.
Malfunction of the air mixing 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 VENTILATION55-41
DTC B1061, B1062: Mode Selection Damper Control Motor and Potentiometer
.
DTC SET CONDITION
DTC B1061 or B1062 is set if there is an open or
short circuit in the potentiometer input circuit, or if
there is an open in the power circuit or ground cir-
cuit.
.
TECHNICAL DESCRIPTION (COMMENT)
Current trouble
The A/C-ECU, the mode selection damper con-
trol motor and potentiometer, or connector(s) or
wiring between the two may be defective.Past trouble
If DTC B1061 or B1062 is stored as a past trou-
ble, carry out diagnosis with particular emphasis
on wiring and connector(s) between the A/C-ECU
and the mode selection damper control motor
and potentiometer. 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.
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 VENTILATION55-48
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 VENTILATION55-54
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 VENTILATION55-56
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 VENTILATION55-60
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)