Mitsubishi 380. Manual — part 178

AUTO A/C DIAGNOSIS

HEATER, AIR CONDITIONING AND VENTILATION

55-8

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

CAUTION

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".

00DB076A

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

AUTO A/C DIAGNOSIS

HEATER, AIR CONDITIONING AND VENTILATION

55-9

DIAGNOSTIC TROUBLE CODE CHART

M1554004900214

CAUTION

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
PAGE

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

U1111

Multi-center display unit (middle grade type) time-out

P.55-60

U1120

Failure information on Electronic control unit (related to engine)

P.55-64

AUTO A/C DIAGNOSIS

HEATER, AIR CONDITIONING AND VENTILATION

55-10

DIAGNOSTIC TROUBLE CODE PROCEDURES

DTC B1001, B1002: Interior Temperature Sensor System.

DTC SET CONDITION

• DTC B1001 is set if there is a short circuit in the

interior temperature sensor input circuit.

• DTC B1002 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 interior air temperature sensor,

or connector(s) or wiring between the two may be
defective.

Past trouble

• If DTC B1001 or B1002 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 interior air temperature sensor. If the con-
nectors 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 interior temperature 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

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)

25DB068A

C-16 (B)

C-15 (B)

CONNECTORS: C-15, C-16

25DB069A

CONNECTOR: C-123

C-123

AUTO A/C DIAGNOSIS

HEATER, AIR CONDITIONING AND VENTILATION

55-11

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.

00DB076A

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827