Mitsubishi Lancer (4A9 engine). Manual - part 267

TROUBLESHOOTING

CONTROLLER AREA NETWORK (CAN)

54C-92

Diagnosis Item 17: Diagnose when the M.U.T.-III cannot receive the data sent by SRS-ECU

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-93

ACB02645

AO

C-04 (GR)

Connectors: C-04, C-122 <LHD>

C-122 (Y)

ACB02647

AK

C-04 (GR)

Connectors: C-04, C-122 <RHD>

C-122 (Y)

TROUBLESHOOTING

CONTROLLER AREA NETWORK (CAN)

54C-94

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

TROUBLE JUDGEMENT CONDITIONS
If a communication flag is not set for the SRS-ECU, 
the ETACS-ECU determines that there is a failure.

TROUBLESHOOTING HINTS

• Malfunction of the connector [joint connector 

(CAN1) or SRS-ECU connector improperly con-
nected]

• Malfunction of the wiring harness [open circuit 

between the SRS-ECU connector and the joint 
connector (CAN1), or power supply circuit to the 
SRS-ECU]

• Malfunction of the SRS-ECU

DIAGNOSIS PROCEDURE

STEP 1. Connector check: C-04 joint connector 
(CAN1) and C-122 SRS-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-122 
SRS-ECU connector and C-04 joint connector 
(CAN1)

CAUTION

Strictly observe the specified wiring harness 
repair procedure. For details refer to .
Disconnect SRS-ECU connector and joint connector 
(CAN1), and check the following wiring harness for 
open circuit
(1) The wiring harness between C-122 SRS-ECU 

connector terminal No.15 and C-04 joint 
connector (CAN1) terminal No.10 <CAN_H>

OK: Continuity exists (2 

Ω or less)

(2) The wiring harness between C-122 SRS-ECU 

connector terminal No.16 and C-04 joint 
connector (CAN1) terminal No.21 <CAN_L>

OK: Continuity exists (2 

Ω or less)

Q: Is the check result normal?

YES : 

Check the power supply circuit of the SRS-

ECU. Refer to GROUP 52B 

− 

Troubleshooting .

NO : 

Repair the wiring harness.

TROUBLESHOOTING

CONTROLLER AREA NETWORK (CAN)

54C-95

Diagnosis Item 18: Diagnose when the M.U.T.-III cannot receive the data sent by heater control unit 
<vehicles without A/C> or A/C-ECU <vehicles with A/C>

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.