2005 MITSUBISHI 380 ECU

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-125
STEP 5. Check the wiring harness between A/C-ECU
connector C-16 (terminal 36) and the ignition switch (ACC).
NOTE: Also check intermediate connector C-29 for loose, cor-
roded, or damaged terminals, or terminals pushed back in the
connector. If intermediate connector C-29 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-16
(terminal 36) and the ignition switch (ACC) in good
condition?
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 : Repair the wiring harness. Check that the air
conditioning works normally.

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-126
STEP 6. Measure the voltage at A/C-ECU connector C-15.
(1) Disconnect A/C-ECU connector C-16 and measure the
voltage at the harness side.
(2) Measure the voltage between terminal 3 and ground.
The measured value should be approximately 12 volts
(battery positive voltage).
Q: Is the measured voltage approx. 12 volts?
YES : Go to Step 8.
NO : Go to Step 7.
STEP 7. Check the wiring harness between A/C-ECU
connector C-15 (terminal 3) and the battery.

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-127
NOTE: Also check intermediate connector C-29 for loose, cor-
roded, or damaged terminals, or terminals pushed back in the
connector. If intermediate connector C-29 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-16
(terminal 3) and the battery in good condition?
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 : Repair the wiring harness. Check that the air
conditioning works normally.
STEP 8. Measure the resistance at A/C-ECU connector
C-16.
(1) Disconnect A/C-ECU connector C-16, and measure at the
wiring harness side.
(2) Measure the resistance between terminal 27 and ground.
The measured value should be 2 ohms or less.
Q: Does the measured resistance value correspond with
this range?
YES : Replace the A/C-ECU, and check that the air
conditioning works normally.
NO : Go to Step 9.

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-128
STEP 9. Check the wiring harness between A/C-ECU
connector C-16 (terminal 27) and the ground.
Q: Is the wiring harness between A/C-ECU connector C-16
(terminal 27) and ground in good condition?
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. check
that the air conditioning works normally.
NO : Repair the wiring harness. Check that the air
conditioning works normally.
INSPECTION PROCEDURE 12: When Sunlight Intensity Changes, Air Outlet Temperature Does Not
Change.
.
CIRCUIT OPERATION
When the blower air temperature cannot be changed
even if the preset temperature is changed, the sen-
sors may be defective.
.
TROUBLESHOOTING HINTS
Improper amount of refrigerant
Malfunction of the A/C pressure sensor
Malfunction of the photo sensor
Malfunction of the A/C-ECU
The wiring harness or connectors may have
loose, corroded, or damaged terminals, or termi-
nals pushed back in the connector.
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 VENTILATION55-129
DIAGNOSIS
Required Special Tools:
: Scan 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. Check the defogger and outside/inside air
selection damper control motor operation.
Q: Do the defogger and outside/inside air selection damper
control motor work normally?
YES : Go to Step 2.
NO : Refer to GROUP 55, AUTO A/C Diagnosis, P.55-70.
STEP 2. Using scan tool , read diagnostic trouble code.
To prevent damage to scan tool , always turn the ignition
switch to the "LOCK" (OFF) position before connecting or
disconnecting scan tool .
Check if an A/C-ECU DTC is set.
1. Connect scan 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 DTC set?
YES : Refer to P.55-9.
NO : Go to Step 3.

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-131
STEP 4. Check A/C-ECU connectors C-15, C-16 and photo
sensor connector C-04 for loose, corroded or damaged
terminals, or terminals pushed back in the connector.
Q: Are A/C-ECU connectors C-15, C-16 and photo sensor
connector C-04 in good condition?
YES : Go to Step 5.
NO : Repair or replace the connector. Refer to GROUP
00E, Harness Connector Inspection P.00E-2. Check
that the air conditioning works normally.

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-132
STEP 5. Check the wiring harness between photo sensor
connector C-04 (terminals 3, 4) and A/C-ECU connector
C-15 (terminal 19), C-16 (terminal 25).
Q: Is the wiring harness between photo sensor connector
C-04 (terminals 3, 4) and A/C-ECU connector C-15
(terminal 19), C-16 (terminal 25) in good condition?
YES : Go to Step 6.
NO : Repair the wiring harness. Check that the air
conditioning works normally.
STEP 6. Replace the photo sensor.
Q: Does the A/C operate normally?
YES : No action is necessary and testing is complete.
NO : Replace the A/C-ECU. Check that the air conditioning
works normally.
STEP 7. Check the refrigerant level.
Use the refrigerant recovery station to remove all of the refrig-
erant, and then calculate the amount of the refrigerant and
charge it.
Q: Is the refrigerant level correct?
YES : Refer to GROUP 55A, Symptom Chart P.55-68.
NO : Correct the refrigerant level. Check that the air
conditioning works normally. (Refer to GROUP 55A
On-vehicle Service P.55-141).

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-137
CHECK AT A/C-ECU TERMINALM1552010300572
TERMINAL
NO.CHECK ITEM CHECKING REQUIREMENTS NORMAL CONDITION
1 Air mixing damper control motor When the air mix damper is
moved to the MAX. COOL
position. 10 V
When the air mix damper is
moved to the MAX. HOT
position. 0.5 V
2 Air mixing damper control motor When the air mix damper is
moved to the MAX. COOL
position. 0.5 V
When the air mix damper is
moved to the MAX. HOT
position. 10 V
3 Back-up power supply Always Battery positive voltage
4 Mode selection damper control
motor (DEF)When the damper is moved to
the FACE position. 0.5 V
When the damper is moved to
the DEF position. 10 V
5 Outside/inside air selection
damper control motor (outside)When the damper is moved to
the inside air recirculation
position.0.5 V
When the damper is moved to
the outside air induction
position.0 V (when the motor is
stopped)
6 Outside/inside air selection
damper control motor (inside)When the damper is moved to
the inside air recirculation
position.0 V (when the motor is
stopped)
When the damper is moved to
the outside air induction
position.0.5 V
8 Rear defogger relay Ignition switch: ON Battery positive voltage
9 Front blower relay Ignition switch: ON Battery positive voltage
10 A/C compressor relay A/C compressor relay: ON Battery positive voltage
11 Mode selection damper control
motor (FACE)When the damper is moved to
the FACE position. 10 V
When the damper is moved to
the DEF position. 0.5 V
12 A/C pressure sensor Ignition switch: ON 5 V