Mitsubishi Lancer (4A9 engine). Manual - part 282

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55A-9

DIAGNOSIS CODE CHART

M1554004901961

<VEHICLES WITHOUT A/C>

Code No.

Diagnostic item

Reference page Service data 

display 
contents when 
diagnosis code 
is set

B1034 (set by 
ETACS-ECU)

Ambient temperature sensor system (short 
circuit)

20

°C

B1035 (set by 
ETACS-ECU)

Ambient temperature sensor system (open 
circuit)

B1031

Fin thermo sensor system (short circuit) 
<Vehicles without A/C>

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

°C

B1032

Fin thermo sensor system (open circuit) 
<Vehicles without A/C>

B1000

Communication error with control panel 
<Vehicles without A/C>

−

B1018

Temperature control dial SW error <Vehicles 
without A/C>

−

B1003

Mode dial SW error <Vehicles without A/C>

−

B1021

Fan dial SW error <Vehicles without A/C>

−

B2214

Control panel failure <Vehicles without A/C>

−

U1415

Coding Not Completed

−

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

−

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

<VEHICLES WITH A/C>

Code No.

Diagnostic item

Reference page Service data 

display 
contents when 
diagnosis code 
is set

B1034 (set by 
ETACS-ECU)

Ambient temperature sensor system (short 
circuit)

20

°C

B1035 (set by 
ETACS-ECU)

Ambient temperature sensor system (open 
circuit)

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55A-10

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

B1031

Fin thermo sensor system (short circuit) 
<Vehicles with A/C>

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

°C

B1032

Fin thermo sensor system (open circuit) 
<Vehicles with A/C>

B1000

Communication error with control panel 
<Vehicles with A/C>

−

B1018

Temperature control dial SW error <Vehicles with 
A/C>

−

B1003

Mode dial SW error <Vehicles with A/C>

−

B1021

Fan dial SW error <Vehicles with A/C>

−

B1079

A/C refrigerant leaks

−

B2214

Control panel failure <Vehicles with A/C>

−

U1415

Coding Not Completed

−

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

−

Code No.

Diagnostic item

Reference page Service data 

display 
contents when 
diagnosis code 
is set

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55A-11

DIAGNOSIS CODE PROCEDURES

Code No.B1034: Ambient temperature sensor system (short circuit)

 

Code No.B1035: Ambient temperature sensor system (open circuit)

Ambient Temperature Sensor Circuit

ETACS-ECU

AMBIENT
TEMPERATURE
SENSOR

ANALOG
INTERFACE
CIRCUIT

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

AC802248

AC612690

AH

Connectors: A-41

A-41 (B)

AC612709

AN

Connector: C-312 <LHD>
ETACS-ECU

AC612717

AK

Connector: C-312 <RHD>
ETACS-ECU

COMMENTS ON TROUBLE SYMPTOM
This code is set when the ambient temperature sen-
sor circuit is short (Code No.B1034) or is open (Code 
No.B1035).

POSSIBLE CAUSES

• Malfunction of the ambient temperature sensor

• Damaged wiring harness or connectors

• Malfunction of the ETACS-ECU

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55A-12

DIAGNOSIS PROCEDURE

STEP 1. Connector check: A-41 ambient 
temperature sensor connector and C-312 ETACS-
ECU connector

Q: Is the check result normal?

YES : 

Go to Step 2.

NO : 

Repair the connector.

STEP 2. Check the wiring harness between A-41 
ambient temperature sensor connector 
(terminals 1 and 2) and C-312 ETACS-ECU 
connector (terminals 14 and 7).

• 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 connector.

STEP 3. Check the ambient temperature sensor
Refer to .

Q: Is the check result normal?

YES : 

Go to Step 4.

NO : 

Replace the ambient temperature sensor.

STEP 4. Check whether the diagnosis code is 
reset

Q: Is the diagnosis code set?

YES : 

Replace the ETACS-ECU.

NO : 

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

Code No.B1031: Fin thermo Sensor system (short circuit) <Vehicles without A/C>

 

Code No.B1032: Fin thermo Sensor system (open circuit) <Vehicles without A/C>

Fin Thermo Sensor Circuit

FIN THERMO
SENSOR

HEATER 
CONTROL 
UNIT

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

AC801264

AC612706

Connectors: C-59, C-118 <LHD>

BO

C-59 (B)

C-118

COMMENTS ON TROUBLE SYMPTOM
This code is set when the fin thermo sensor circuit is 
short (Code No.B1031) or is open (Code No.B1032).

PROBABLE CAUSES

• Malfunction of the fin thermo sensor

• Damaged wiring harness or connectors

• Malfunction of the heater control unit