Mitsubishi Lancer (4A9 engine). Manual - part 312

TROUBLESHOOTING

AUTOMATIC AIR CONDITIONER

55B-2

TROUBLESHOOTING

DIAGNOSIS TROUBLESHOOTING FLOW

M1554004700577

Refer to GROUP 00, How to Use Troubleshooting/
Inspection Service Points 

− Contents of Trouble-

shooting 

DIAGNOSIS FUNCTION

M1554004800916

READING DIAGNOSIS CODES

Refer to GROUP 00, How to Use Troubleshooting/
Inspection Service Points 

− Diagnosis Function .

ERASING DIAGNOSIS CODES

Refer to GROUP 00, How to Use Troubleshooting/
Inspection Service Points 

− Diagnosis Function .

CHECK OF FREEZE FRAME DATA

The freeze frame data can be checked by using the 
M.U.T.-III.
When detecting fault and storing the diagnosis code, 
the ECU connected to CAN bus line obtains the data 
before the determination of the diagnosis code and 
the data when the diagnosis code is determined, and 
then stores the ECU status of that time. By analysing 
each data from M.U.T.-III, the troubleshooting can be 
performed more efficiently. The displayed items are 
as the table below.

Display item list

Item No.

Item name

Data item

Unit

1

Odometer

Total driving distance after the diagnosis code is 
generated

km

2

Ignition cycle

Number of times the ignition switch is turned "ON" or 
"LOCK (OFF)" after the past failure transition

Number of 
counts is 
displayed.

4

Current trouble 
accumulative time

Cumulative time for current malfunction of diagnosis 
code

min

DIAGNOSIS CODE CHART

M1554004901972

Code No.

Diagnostic item

Reference page Service data 

display 
contents when 
diagnosis code 
is set

B10C0 (set by A/C-
ECU)

Interior temperature sensor system (short circuit)

25

°C

B10C1 (set by A/C-
ECU)

Interior temperature sensor system (open circuit)

TROUBLESHOOTING

AUTOMATIC AIR CONDITIONER

55B-3

NOTE: Note that diagnosis code Nos. B1034 and 
B1035 will be set by the ETACS-ECU separately.

B1034 (set by 
ETACS-ECU)

Ambient air temperature sensor system (short 
circuit)

Refer to GROUP 
55A Diagnosis 
Code Chart 

20

°C

B1035 (set by 
ETACS-ECU)

Ambient air temperature sensor system (open 
circuit)

B1031

Air thermo sensor system (short circuit)

Air recirculation 
position: Interior 
temperature
Fresh air 
position: Fresh 
air + 10

°C

B1032

Air thermo sensor system (open circuit)

B1000

Control panel communication error

−

B1018

Temperature adjusting SW

−

B1003

Mode changeover SW

−

B1021

Blower fan SW

−

B1079

A/C refrigerant leaks

−

B2214

Control panel failure

−

B1415

Coding incomplete

−

U0019

Bus off (CAN-B)

−

U0141

ETACS-ECU CAN time-out

−

U0151

SRS CAN time-out

−

U0155

Meter CAN time-out

−

U0168

WCM CAN time-out

−

U0184

Audio CAN time-out

−

U0197

Hands Free Module Time-out

−

Code No.

Diagnostic item

Reference page Service data 

display 
contents when 
diagnosis code 
is set

TROUBLESHOOTING

AUTOMATIC AIR CONDITIONER

55B-4

DIAGNOSIS CODE PROCEDURES

Code No.B10C0: Interior temperature sensor system (short circuit)

 

Code No.B10C1: Interior temperature sensor system (open circuit)

Interior Temperature Sensor Circuit

A/C-ECU

INTERIOR
TEMPERATURE
SENSOR

Wire colour code 
B : Black     LG : Light green     G : Green     L : Blue     W : White     Y : Yellow     SB : Sky blue 
BR : Brown     O : Orange     GR : Grey     R : Red     P : Pink     V : Violet     PU : Purple     SI : Silver

ACA00730

AC612705

Connector: C-05 <LHD>

IV

AC612706

Connector: C-15 <LHD>

AK

C-15 (B)

AC612711

Connector: C-05 <RHD>

AJ

AC612710

Connector: C-15 <RHD>

EO

C-15 (B)

COMMENTS ON TROUBLE SYMPTOM
This code is set when the interior temperature sensor 
circuit is short (Code No.B10C0) or is open (Code 
No.B10C1)

TROUBLESHOOTING

AUTOMATIC AIR CONDITIONER

55B-5

PROBABLE CAUSES

• Malfunction of the interior temperature sensor

• Damaged the wiring harness or connectors

• Malfunction of the A/C-ECU

DIAGNOSIS PROCEDURE

STEP 1. Connector check: C-05 interior 
temperature sensor connector and C-15 A/C-ECU 
connector

Q: Is the check result normal?

YES : 

Go to Step 2.

NO : 

Repair the connector.

STEP 2. Check the wiring harness between C-15 
A/C-ECU connector (terminals 19 and 17) and C-
05 interior temperature sensor connector 
(terminals 1 and 2).

• Check the sensor signal line and earth line for 

open or short circuit.

Q: Is the check result normal?

YES : 

Go to Step 3.

NO : 

Repair the wiring harness.

STEP 3. Check the interior temperature sensor.
Refer to .

Q: Is the check result normal?

YES : 

Go to Step 4.

NO : 

Replace the interior temperature sensor.

STEP 4. Check whether the diagnosis code is 
reset.

Q: Is the diagnosis code set?

YES : 

Replace the A/C-ECU.

NO : 

The trouble can be an intermittent 
malfunction (Refer to GROUP 00, How to 
Cope with Intermittent Malfunction ).

DATA LIST REFERENCE TABLE

M1554005101043

Item No.

Check item

Inspection status

The display contents 
under normal condition

17

Engine speed

−

Displays correct engine 
speed.

19

Ambient temperature 
sensor

−

Ambient temperature is the 
same as M.U.T.-III displayed 
temperature

20

Fin thermo sensor

−

Evaporator outlet 
temperature is the same as 
M.U.T.-III displayed 
temperature.

21

Interior temperature 
sensor

−

Interior temperature is the 
same as M.U.T.-III displayed 
temperature

23

Temperature setting

Displays air conditioner set 
temperature.

24

Engine coolant TEMP 
sensor

−

Engine coolant temperature 
is the same as M.U.T.-III 
displayed temperature.

26

Vehicle speed

−

Displays vehicle speed.

27

A/C Compressor drive 
request

Compressor ON

ON

Compressor OFF

OFF

28

Air conditioning switch

Air conditioner switch ON

ON

Air conditioner switch OFF

OFF

29

Refrigerant leak

−

Normal

34

Idle up request

−

Displays idle-up request 
signal.