Mitsubishi Lancer (4A9 engine). Manual - part 263

TROUBLESHOOTING

CONTROLLER AREA NETWORK (CAN)

54C-76

Diagnosis Item 12: Diagnose when the M.U.T.-III cannot receive the data sent by engine-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-C Communication Circuit <Except for RALLIART>

ETACS-ECU

INTERFACE 
CIRCUIT

CAN DRIVE 
CIRCUIT

ASC-ECU

A/T-ECU

ABS-ECU

CVT-ECU

STEERING 
WHEEL SENSOR 
<AFS, ASC>

ENGINE-ECU

ELECTRIC 
POWER 
STEERING-ECU

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

CORNER SENSOR/
BACK SENSOR-ECU

DIESEL

:

PETROL

:

1800-PETROL, 2000

:

NOTE

PETROL (EXCEPT SOHC)

:

VEHICLES WITHOUT ASC

:

VEHICLES WITH ASC

:

HEADLAMP 
AUTOMATIC 
LEVELLING-ECU

AS&G-ECU

TROUBLESHOOTING

CONTROLLER AREA NETWORK (CAN)

54C-77

AC800715

Connectors: B-09, B-40

BC

B-09 (GR), 
B-40 (B)

ACB02645

AH

Connector: C-124 <LHD>

C-124 (GR)

ACB02647

AE

C-124 (GR)

Connector: C-124 <RHD>

TROUBLESHOOTING

CONTROLLER AREA NETWORK (CAN)

54C-78

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

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

TROUBLESHOOTING HINTS

• Malfunction of the connector [joint connector 

(CAN3) and engine-ECU connector improperly 
connected]

• Malfunction of the wiring harness [open circuit 

between the engine-ECU and the joint connector 
(CAN3) power supply circuit to the engine-ECU]

• Malfunction of the engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. Connector check: B-09 <Petrol> or B-40 
<Diesel> engine-ECU connector and C-124 joint 
connector (CAN3)

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 B-09 
<Petrol> or B-40 <Diesel> engine-ECU connector 
and C-124 joint connector (CAN3)

CAUTION

Strictly observe the specified wiring harness 
repair procedure. For details refer to .
Disconnect engine-ECU connector and joint connec-
tor (CAN3) and check the following wiring harness 
for open circuit.
(1) The wiring harness between B-09 <Petrol> or B-

40 <Diesel> engine-ECU connector terminal 
No.90 <Petrol> or 108 <Diesel> and C-124 joint 
connector (CAN3) terminal No.4 <CAN_H>

OK: Continuity exists (2 

Ω or less)

(2) The wiring harness between B-09 <Petrol> or B-

40 <Diesel> engine-ECU connector terminal 
No.91 <Petrol> or 109 <Diesel> and C-124 joint 
connector (CAN3) terminal No.15 <CAN_L>

OK: Continuity exists (2 

Ω or less)

Q: Is the check result normal?

YES : 

Check the power supply circuit of the 

engine-ECU. Refer to GROUP 13A 

− 

Troubleshooting  <1600>, GROUP 13B 

− 

Troubleshooting  <Petrol (1800-DOHC), 
2000>, GROUP 13C 

− Troubleshooting  

<Diesel> or GROUP 13F 

− Troubleshooting  

<1800-SOHC>

NO : 

Repair the wiring harness.

TROUBLESHOOTING

CONTROLLER AREA NETWORK (CAN)

54C-79

Diagnosis Item 13: Diagnose the lines between the ETACS-ECU and joint connector (CAN2)

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.