Mitsubishi Lancer (4A9 engine). Manual - part 271

TROUBLESHOOTING

CONTROLLER AREA NETWORK (CAN)

54C-108

Diagnosis Item 22: Diagnose when the M.U.T.-III cannot receive the data sent by AS&G-ECU <vehicles 
with automatic stop & go (AS&G) system>

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.

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-109

ACA00830AD

Connector: C-64 <LHD>

C-64

ACB02647

AO

C-64

C-124 (GR)

Connectors: C-64, C-124 <RHD>

ACB02645

AH

Connector: C-124 <LHD>

C-124 (GR)

TROUBLESHOOTING

CONTROLLER AREA NETWORK (CAN)

54C-110

FUNCTION
If the M.U.T.-III cannot communicate with the AS&G-
ECU, this diagnosis result will be set.

TROUBLE JUDGMENT CONDITIONS
If a communication flag is not set for the AS&G-ECU, 
the ETACS-ECU determines that there is a failure.

TROUBLESHOOTING HINTS

• Malfunction of the connector [joint connector 

(CAN3) or AS&G-ECU connector improperly con-
nected]

• Malfunction of the wiring harness [open circuit 

between the AS&G-ECU and the joint connector 
(CAN3), power supply circuit to the AS&G-ECU]

• Malfunction of the AS&G-ECU

DIAGNOSIS PROCEDURE

STEP 1. Connector check: C-04 joint connector 
(CAN1) and C-64 AS&G-ECU connector

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-64 
AS&G-ECU connector and C-124 joint connector 
(CAN1)

CAUTION

Strictly observe the specified wiring harness 
repair procedure. For details refer to .
Disconnect hands AS&G-ECU connector and joint 
connector (CAN1), and check the continuity of the 
following wiring harness.
(1) The wiring harness between C-64 AS&G-ECU 

connector terminal No.1 and C-124 joint 
connector (CAN3) terminal No.17 <Diesel> or 16 
<Petrol> <CAN_H>

OK: Continuity exists (2 

Ω or less)

(2) The wiring harness between C-64 AS&G-ECU 

connector terminal No.14 and C-124 joint 
connector (CAN3) terminal No.6 <Diesel> or 5 
<Petrol> <CAN_L>

OK: Continuity exists (2 

Ω or less)

Q: Is the check result normal?

YES : 

Check the power supply circuit of the hands 

free-ECU. Refer to GROUP 17 

−  automatic 

stop & go (AS&G) system 

− Troubleshooting 

.

NO : 

Repair the wiring harness.

TROUBLESHOOTING

CONTROLLER AREA NETWORK (CAN)

54C-111

Diagnosis Item 23: Short to power supply or earth in both CAN_H and CAN_L lines of the CAN-B bus 
lines.

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.