2005 MITSUBISHI 380 Ignition circuit

GENERAL DESCRIPTION
HEATER, AIR CONDITIONING AND VENTILATION55-4
OPERATION
.
CONDENSER FAN AND RADIATOR FAN
CONTROL
The ECU judges the required revolution speed of
radiator fan motor and condenser fan motor using
the input signals transmitted from A/C switch, output
shaft speed sensor and engine coolant temperature
sensor. The ECU activates the fan control relays to
drive the radiator fan motor and condenser fan
motor.
.
COMPRESSOR CONTROL
When operating the air conditioning switch
The air thermo sensor, which senses the temper-
ature of the air flowing out of the evaporator,
deactivates the compressor at 3
C (37.4F) or
below.
The dual pressure switch turns OFF when the
refrigerant pressure becomes excessively high or
low, thus protecting the compressor circuit (See
Table below).
When the air thermo sensor is activated, and the
ignition switch, blower switch, and air condition-
ing switch are ON, the A/C compressor clutch
relay is energized.
When operating the mode selection dial
The air conditioning will work when the mode
selection dial is set to the "Defroster" or
"Defroster/foot" position, or the temperature con-
trol dial is set to the "MAX A/C" position. In other
dial positions, when the air conditioning switch is
turned on, the air conditioning will work.
A/C Compressor Clutch Relay ON Conditions
Ignition switch (IG2) ONNOTE: A/C compressor clutch relay is
de-energized when any one switch, sensor
or control unit shown on the left turns off.
NOTE: The components marked by
*
communicate with the ECU. If the air thermo
sensor detects a temperature of 3
C
(37.4
F), the A/C-ECU will turn off the A/C
compressor clutch relay. Blower switch ON
Air conditioning switch, mode selection dial
defroster, defroster/foot position or temperature
control MAX A/CON
Air thermo sensor*
Pressure detected
by A/C pressure
sensor2940 kPa or less (If the
refrigerant pressure exceeds
2940 kPa, A/C compressor
clutch relay is not ON
condition until the refrigerant
pressure has been measured
up to 2350 kPa or less.)ON
190 kPa or more (If the
refrigerant pressure falls short
of 190 kPa, A/C compressor
clutch relay is not ON
condition until the refrigerant
pressure has been measured
up to 220 kPa or more.)
A/C compressor clutch relay driving transistor (within
ecu)ON

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-9
DIAGNOSTIC TROUBLE CODE CHART M1554004900214
During diagnosis, a DTC code associated with
other system may be set when the ignition switch
is turned on with connector(s) disconnected. On
completion of repairs, confirm all systems for
DTC code(s). If DTC code(s) are set, erase them
all.
DIAGNOSTIC
TROUBLE CODE
NO.DIAGNOSTIC ITEM REFERENCE
PA G E
B1001 Interior temperature sensor system (short circuit)
P.55-10
B1002 Interior temperature sensor system (open circuit)
P.55-10
B1011 Ambient air temperature sensor system (short circuit)
P.55-16
B1012 Ambient air temperature sensor system (open circuit)
P.55-16
B1021 Air thermo sensor system (short circuit)
P.55-22
B1022 Air thermo sensor system (open circuit)
P.55-22
B1041 Air mixing damper control motor and potentiometer (potentiometer
system shorted to its power supply)P.55-28
B1042 Air mixing damper control motor and potentiometer (potentiometer
system shorted to its ground)P.55-28
B1045 Air mixing damper control motor and potentiometer (activating
system failure)P.55-35
B1061 Mode selection damper control motor and potentiometer
(potentiometer system shorted to its power supply)P.55-41
B1062 Mode selection damper control motor and potentiometer
(potentiometer system shorted to its ground)P.55-41
B1065 Mode selection damper control motor and potentiometer (activating
system failure)P.55-48
U1073 Bus off
P.55-54
U1100
Electronic control unit time-out (related to engine)P.55-56
U 1111 M u l t i - c e n t e r d i s p l a y u n i t ( m i d d l e g r a d e t y p e ) t i m e - o u t
P.55-60
U1120 Failure information on Electronic control unit (related to engine)
P.55-64

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 VENTILATION55-58
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 VENTILATION55-62
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).

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-63
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).