Page 707 of 1500

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-6
HOW TO READ AND ERASE DIAGNOSTIC
TROUBLE CODES
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)
To prevent damage to diagnostic tool , always turn the
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting diagnostic tool .
NOTE: If the battery voltage is low, diagnostic trouble codes will
not be output. Check the battery if diagnostic tool does not dis-
play.
1. Connect the diagnostic tool to the data link connector.
2. Turn the ignition switch to the "ON" position.
3. Select "Interactive Diagnosis" from the start-up screen.
4. Select "System Select."
5. Choose "AUTO A/C" from the "BODY" tab.
6. Select "MITSUBISHI."
7. Select "Diagnostic Trouble Code."
8. If a DTC is set, it is shown.
9. Choose "Erase DTC" to erase the DTC.
HOW TO READ DATA LIST
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)
Page 708 of 1500

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-7
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 the diagnostic tool to the data link connector.
2. Turn the ignition switch to the "ON" position.
3. Select "Interactive Diagnosis" from the start-up screen.
4. Select "System Select."
5. Choose "AUTO A/C" from the "BODY" tab.
6. Select "MITSUBISHI."
7. Select "Data List."
8. Choose an appropriate item and select the "OK" button.
HOW TO PERFORM ACTUATOR TEST
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)
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 the diagnostic tool to the data link connector.
2. Turn the ignition switch to the "ON" position.
3. Select "Interactive Diagnosis" from the start-up screen.
4. Select "System Select."
5. Choose "AUTO A/C" from the "BODY" tab.
6. Select "MITSUBISHI."
7. Choose "Actuator Test" from "AUTO A/C" screen.
8. Choose an appropriate item and select the "OK" button.
Page 709 of 1500

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-8
HOW TO DIAGNOSE THE CAN BUS LINE
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
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. Turn the ignition switch to the "ON" position.
3. Select "CAN bus diagnosis" from the start-up screen.
4. When the vehicle information is displayed, confirm that it
matches the vehicle whose CAN bus lines will be
diagnosed.
If they match, go to step 8.
If not, go to step 5.
5. Select "view vehicle information" button.
6. When the vehicle information is displayed, confirm again
that it matches the vehicle which is diagnosed CAN bus line.
If they match, go to step 8.
If not, go to step 5.
7. Press the "OK" button.
8. When the options are displayed, choose the options (mark
the check) and then select "OK".
Page 710 of 1500

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
Page 712 of 1500
AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-11
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. (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.
Page 713 of 1500
AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-12
STEP 3. Using diagnostic tool , check data list item 59:
Inside temperature 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) Start the engine.
(3) Set diagnostic tool to the data reading mode for item 59:
Inside temperature sensor.
Check that the interior temperature matches the dis-
played value on the diagnostic tool.
NOTE: When this DTC is set and the system is in fail-safe
status, the value of service data displays 25
C.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Does the interior temperature match the displayed value
on the diagnostic tool?
YES : Replace the A/C-ECU. Then go to Step 7.
NO : Go to Step 4.
Page 716 of 1500
AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-15
STEP 6. Check the interior temperature sensor.
(1) Disconnect interior temperature sensor connector C-123.
(2) When the resistance between the sensor terminals is
measured under two or more temperature conditions, the
resistance should approximately satisfy the illustrated
values.
NOTE: The temperature conditions when checking should
not exceed the range shown in the diagram.
Q: Is the interior temperature sensor in good condition?
YES : Replace the A/C-ECU. Then go to Step 7.
NO : Replace the interior temperature sensor. Then go to
St e p 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.
Page 718 of 1500

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-17
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 8.
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.