Mitsubishi Lancer (4A9 engine). Manual - part 268

CAN-B Communication Circuit

ETACS-ECU

INTERFACE 
CIRCUIT

CAN DRIVE 
CIRCUIT

SRS-ECU

CPU

WCM

CAN BOX UNIT

KOS-ECU

CAN 
TRANSCEIVER 
CIRCUIT

CAN DRIVE 
CIRCUIT

CAN DRIVE 
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

RADIO AND 
CD PLAYER

CAN 
TRANSCEIVER 
CIRCUIT

INTERFACE 
CIRCUIT

VEHICLES WITHOUT A/C

:

VEHICLES WITH A/C

:

VEHICLES WITH KOS

:

NOTE

VEHICLES WITH WCM

:

VEHICLES WITH RADIO AND CD PLAYER

:

VEHICLES WITHOUT AUDIO

:

VEHICLES WITH MMCS

:

COMBINATION 
METER

HEATER CONTROL
PANEL
A/C-ECU

SPARE 
CONNECTOR 
(FOR AUDIO)

TROUBLESHOOTING

CONTROLLER AREA NETWORK (CAN)

54C-96

ACB02645

AL

C-04 (GR)

Connector: C-04 <LHD>

ACB02647

AH

C-04 (GR)

Connector: C-04 <RHD>

AC709894

AF

Connector: C-15 <LHD>

C-15 (B)

AC701121BT

Connector: C-15 <RHD>

C-15 (B)

TROUBLESHOOTING

CONTROLLER AREA NETWORK (CAN)

54C-97

FUNCTION
If the M.U.T.-III cannot communicate with the heater 
control unit <vehicles without A/C> or A/C-ECU 
<vehicles with A/C>, this diagnosis result will be set.

TROUBLE JUDGEMENT CONDITIONS
If a communication flag is not set for the heater con-
trol unit <vehicles without A/C> or A/C-ECU <vehi-
cles with A/C>, the ETACS-ECU determines that 
there is a failure.

TROUBLESHOOTING HINTS

• Malfunction of the connector [joint connector 

(CAN1) or heater control unit <vehicles without A/
C> or A/C-ECU <vehicles with A/C> connector 
improperly connected]

• Malfunction of the wiring harness [open circuit 

between the heater control unit <vehicles without 
A/C> or A/C-ECU <vehicles with A/C> connector 
and the joint connector (CAN1), or power supply 
circuit to the heater control unit <vehicles without 
A/C> or A/C-ECU <vehicles with A/C>]

• Malfunction of the heater control unit <vehicles 

without A/C> or A/C-ECU <vehicles with A/C>

DIAGNOSIS PROCEDURE

STEP 1. Connector check: C-04 joint connector 
(CAN1) and C-60 heater control unit connector 
<vehicles without A/C> or C-15 A/C-ECU 
connector <vehicles with A/C>

CAUTION

The strand end of the twist wire should be within 
10 cm from the connector. For details refer to .

Q: Is the check result normal?

YES : 

Go to Step 2.

NO : 

Repair the defective connector.

STEP 2. Check the wiring harness between C-60 
heater control unit connector <vehicles without 
A/C> or C-15 A/C-ECU connector <vehicles with 
A/C> and C-04 joint connector (CAN1)

CAUTION

Strictly observe the specified wiring harness 
repair procedure. For details refer to .
Disconnect heater control unit connector <vehicles 
without A/C> or A/C-ECU connector <vehicles with 
A/C> and joint connector (CAN1), and check the fol-
lowing wiring harness for open circuit
(1) The wiring harness between C-60 heater control 

unit connector <vehicles without A/C> or C-15 A/
C-ECU connector <vehicles with A/C> terminal 
No.11 and C-04 joint connector (CAN1) terminal 
No.8 <CAN_H>

OK: Continuity exists (2 

Ω or less)

(2) The wiring harness between C-60 heater control 

unit connector <vehicles without A/C> or C-15 A/
C-ECU connector <vehicles with A/C> terminal 
No.12 and C-04 joint connector (CAN1) terminal 
No.19 <CAN_L>

OK: Continuity exists (2 

Ω or less)

Q: Is the check result normal?

TROUBLESHOOTING

CONTROLLER AREA NETWORK (CAN)

54C-98

YES : 

Check the power supply circuit of the heater 

control unit <vehicles without A/C> or A/C-
ECU <vehicles with A/C>. Refer to GROUP 
55A, Manual A/C Diagnosis  or GROUP 
55B, Auto A/C Diagnosis .

NO : 

Repair the wiring harness.

TROUBLESHOOTING

CONTROLLER AREA NETWORK (CAN)

54C-99

Diagnosis Item 19: Diagnose when the M.U.T.-III cannot receive the data sent by CAN box unit 
<vehicles with MMCS (vehicles for Russia)>

CAUTION

When servicing a CAN bus line, earth yourself by touching a metal object such as an unpainted water 
pipe. If you fail to do, a component connected to the CAN bus line may be broken.