2005 MITSUBISHI 380 Workshop Manual

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-20
STEP 7. Check the wiring harness between A/C-ECU
connector C-15 (terminals 20), C-16 (terminal 23) and
ambient air temperature sensor connector A-25 (terminals
1 and 2).
NOTE: Also check intermediate connector C-23 for loose, cor-
roded, or damaged terminals, or terminals pushed back in the
connector. If intermediate connector C-23 is damaged, repair or
replace the connector as described in GROUP 00E, Harness
Connector Inspection P.00E-2.
Q: Is the wiring harness between A/C-ECU connector C-15
(terminals 20), C-16(terminal 23) and ambient air
temperature sensor connector A-25 (terminals 1 and 2)
in good condition?
YES : Replace the A/C-ECU. Then go to Step 8.
NO : Repair the wiring harness. Then go to Step 8.

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-21
STEP 8. 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 VENTILATION55-22
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 VENTILATION55-23
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)
STEP 1. Using diagnostic tool , diagnose the CAN bus line.
Use diagnostic tool to diagnose the CAN bus lines.
(1) Connect diagnostic tool to the data link connector.
(2) Turn the ignition switch to "ON" position.
(3) Diagnose the CAN bus line.
Q: Is the check result satisfactory?
YES : Go to Step 2.
NO : Repair the CAN bus lines. Repair the CAN bus lines
(Refer to GROUP 54C, Diagnosis-Can Bus
Diagnostic Chart P.54C-405). Then go to Step 7.
STEP 2. Recheck for diagnostic trouble code.
Recheck if the DTC is set.
(1) Erase the DTC.
(2) Turn the ignition switch to "ON" position.
(3) Check if the DTC is set.
Q: Is the check result satisfactory?
YES : It can be assumed that this malfunction is intermittent.
Refer to GROUP 00, How to Use
Troubleshooting/Inspection Service Points
How to
Cope with Intermittent Malfunctions P.00-14.
NO : Go to Step 3.

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-24
STEP 3. Using diagnostic tool , check data list item 20: Air
thermo sensor.
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) Ignition switch: ON
(3) Set diagnostic tool to the data reading mode for item 20: Air
thermo sensor.
Check that the passenger room temperature matches
the displayed value on the diagnostic tool while the
engine is cold.
NOTE: When this DTC is set and the system is fail-safe sta-
tus, the value of service data displays
6C.
(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.

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-25
STEP 4. Check A/C-ECU connector C-15, C-16 and air
thermo sensor connector C-126 for loose, corroded or
damaged terminals, or terminals pushed back in the
connector.
Q: Are A/C-ECU connector C-15, C-16 and air thermo
sensor connector C-126 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 VENTILATION55-26
STEP 5. Check the wiring harness between A/C-ECU
connector C-15 (terminal 20), C-16 (terminal 24) and air
thermo sensor connector C-126 (terminals 2 and 1).
Q: Is the wiring harness between A/C-ECU connector C-10
(terminal 10 and 13) and air thermo sensor connector
C-126 (terminals 2 and 1) 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 VENTILATION55-27
STEP 6. Check the air thermo sensor.
(1) Disconnect the air thermo sensor connector C-126.
(2) Measure the resistance between connector terminals 1 and
2 under at least two different temperatures. The resistance
values should generally match those in the graph.
NOTE: The temperature at the check should not exceed the
range in the graph.
Q: Is the air thermo sensor in good condition?
YES : Replace the A/C-ECU. Then go to Step 7.
NO : Replace the air thermo sensor. Then go to Step 7.
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.