Mitsubishi Lancer (4A9 engine). Manual - part 272

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-112

ACB02645

AK

C-04 (GR)

C-01

C-06

C-23

Connectors: C-01, C-04, C-06, C-23, C-32,
C-122 <LHD>

C-32 (GR)

C-122 (Y)

ACB02647

AG

C-103, 
C-139

C-04 (GR)

C-01

C-06

Connectors: C-01, C-04, C-06, C-23, C-103,
C-122, C-139 <RHD>

C-23

C-122 (Y)

ACB02646

AF

C-15 (B),
C-60 (B)

Connectors: C-15, C-54, C-60, C-103, C-139
<LHD>

C-54 (G)

C-103,
C-139

ACB02648

AG

C-15 (B)

Connector: C-15<RHD>

ACA00886

BE

Connector: C-301 <LHD>
ETACS-ECU

ACA00887

BF

Connector: C-301 <RHD>
ETACS-ECU

TROUBLESHOOTING

CONTROLLER AREA NETWORK (CAN)

54C-113

FUNCTION
If a short to power supply or earth is present in both 
CAN_H and CAN_L lines, this diagnosis result will be 
set.

TROUBLE JUDGEMENT CONDITIONS
If a communication flag is set for ETACS-ECU and 
no communication is present through the CAN-B 
line, or diagnosis code U0019 is set in the ETACS-
ECU, ETACS-ECU determines that there is a failure.

TROUBLESHOOTING HINTS

• Malfunction of the connector (ETACS-ECU con-

nector improperly connected)

• Malfunction of the wiring harness (CAN_H and 

CAN_L lines are short to power supply or earth 
on the CAN-B line.)

• Malfunction of ECUs

DIAGNOSIS PROCEDURE

STEP 1. Checking short to power supply (voltage 
measurement)

CAUTION

• A digital multimeter should be used. For 

details refer to .

• The test wiring harness should be used. For 

details refer to .

(1) Disconnect C-301 ETACS-ECU connector, and 

measure at the wiring harness side.

(2) Turn the ignition switch to the ON position.
(3) Measure the voltage between C-301 ETACS-

ECU connector terminal No.6 and body earth.

OK: 5 V or less

(4) Measure the voltage between C-301 ETACS-

ECU connector terminal No.7 and body earth.

OK: 5 V or less

Q: Is the check result normal?

YES : 

Go to Step 2.

NO : 

Go to Step 11.

TROUBLESHOOTING

CONTROLLER AREA NETWORK (CAN)

54C-114

STEP 2. Check the wiring harness between C-122 
SRS-ECU connector and C-04 joint connector 
(CAN1) for short to earth (resistance 
measurement).

CAUTION

• Disconnect the negative battery terminal. For 

details refer to .

• A digital multimeter should be used. For 

details refer to .

• The test wiring harness should be used. For 

details refer to .

(1) Disconnect joint connector (CAN1), and measure 

at the wiring harness side.

(2) Measure the resistance between C-04 joint 

connector (CAN1) terminal No.10 and body 
earth.

OK: 1 k

Ω or more

(3) Measure the resistance between C-04 joint 

connector (CAN1) terminal No.21 and body 
earth.

OK: 1 k

Ω or more

Q: Is the check result normal?

YES : 

Go to Step 3.

NO : 

Go to Step 20.

STEP 3. 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> connector and C-04 joint connector (CAN1) 
for short to earth (resistance measurement).

CAUTION

• Disconnect the negative battery terminal. For 

details refer to .

• A digital multimeter should be used. For 

details refer to .

• The test wiring harness should be used. For 

details refer to .

(1) Disconnect joint connector (CAN1), and measure 

at the wiring harness side.

(2) Measure the resistance between C-04 joint 

connector (CAN1) terminal No.8 and body earth.

OK: 1 k

Ω or more

(3) Measure the resistance between C-04 joint 

connector (CAN1) terminal No.19 and body 
earth.

OK: 1 k

Ω or more

Q: Is the check result normal?

YES : 

Go to Step 4.

NO : 

Go to Step 21.

STEP 4. Check the wiring harness between C-01 
combination meter connector and C-04 joint 
connector (CAN1) for short to earth (resistance 
measurement).

CAUTION

• Disconnect the negative battery terminal. For 

details refer to .

• A digital multimeter should be used. For 

details refer to .

• The test wiring harness should be used. For 

details refer to .

(1) Disconnect joint connector (CAN1), and measure 

at the wiring harness side.

(2) Measure the resistance between C-04 joint 

connector (CAN1) terminal No.9 and body earth.

OK: 1 k

Ω or more

(3) Measure the resistance between C-04 joint 

connector (CAN1) terminal No.20 and body 
earth.

OK: 1 k

Ω or more

Q: Is the check result normal?

YES <vehicles without KOS> : 

Go to Step 5.

YES <vehicles with KOS> : 

Go to Step 6.

NO (the check result is not normal.) : 

Go to Step 

22.

STEP 5. Check the wiring harness between C-06 
WCM connector and C-04 joint connector (CAN1) 
for short to earth (resistance measurement).

CAUTION

• Disconnect the negative battery terminal. For 

details refer to .

• A digital multimeter should be used. For 

details refer to .

• The test wiring harness should be used. For 

details refer to .

(1) Disconnect joint connector (CAN1), and measure 

at the wiring harness side.

(2) Measure the resistance between C-04 joint 

connector (CAN1) terminal No.7 and body earth.

OK: 1 k

Ω or more

(3) Measure the resistance between C-04 joint 

connector (CAN1) terminal No.18 and body 
earth.

OK: 1 k

Ω or more

Q: Is the check result normal?

TROUBLESHOOTING

CONTROLLER AREA NETWORK (CAN)

54C-115

YES <vehicles with radio and CD player> : 

Go to 

Step 7.

YES <vehicles with MMCS (vehicles for Russia)> : 

Go to Step 8.

YES <vehicles without MMCS and without radio 
and CD player> : 

Go to Step 9.

NO (the check result is not normal.) : 

Go to Step 

23.

STEP 6. Check the wiring harness between C-23 
KOS-ECU connector and C-04 joint connector 
(CAN1) for short to earth (resistance 
measurement).

CAUTION

• Disconnect the negative battery terminal. For 

details refer to .

• A digital multimeter should be used. For 

details refer to .

• The test wiring harness should be used. For 

details refer to .

(1) Disconnect joint connector (CAN1), and measure 

at the wiring harness side.

(2) Measure the resistance between C-04 joint 

connector (CAN1) terminal No.5 and body earth.

OK: 1 k

Ω or more

(3) Measure the resistance between C-04 joint 

connector (CAN1) terminal No.16 and body 
earth.

OK: 1 k

Ω or more

Q: Is the check result normal?

YES <vehicles with radio and CD player> : 

Go to 

Step 7.

YES <vehicles with MMCS (vehicles for Russia)> : 

Go to Step 8.

YES <vehicles without MMCS and without radio 
and CD player> : 

Go to Step 9.

NO (the check result is not normal.) : 

Go to Step 

24.

STEP 7. Check the wiring harness between C-103 
radio and CD player connector and C-04 joint 
connector (CAN1) for short to earth (resistance 
measurement).

CAUTION

• Disconnect the negative battery terminal. For 

details refer to .

• A digital multimeter should be used. For 

details refer to .

• The test wiring harness should be used. For 

details refer to .

(1) Disconnect joint connector (CAN1), and measure 

at the wiring harness side.

(2) Measure the resistance between C-04 joint 

connector (CAN1) terminal No.6 and body earth.

OK: 1 k

Ω or more

(3) Measure the resistance between C-04 joint 

connector (CAN1) terminal No.17 and body 
earth.

OK: 1 k

Ω or more

Q: Is the check result normal?

YES : 

Go to Step 10.

NO : 

Go to Step 25.

STEP 8. Check the wiring harness between C-54 
CAN box unit connector and C-04 joint connector 
(CAN1) for short to earth (resistance 
measurement).

CAUTION

• Disconnect the negative battery terminal. For 

details refer to .

• A digital multimeter should be used. For 

details refer to .

• The test wiring harness should be used. For 

details refer to .

(1) Disconnect joint connector (CAN1), and measure 

at the wiring harness side.

(2) Measure the resistance between C-04 joint 

connector (CAN1) terminal No.6 and body earth.

OK: 1 k

Ω or more

(3) Measure the resistance between C-04 joint 

connector (CAN1) terminal No.17 and body 
earth.

OK: 1 k

Ω or more

Q: Is the check result normal?

YES : 

Go to Step 10.

NO : 

Go to Step 26.

STEP 9. Check the wiring harness between C-103 
spare connector (for audio) and C-04 joint 
connector (CAN1) for short to earth (resistance 
measurement).

CAUTION

• Disconnect the negative battery terminal. For 

details refer to .

• A digital multimeter should be used. For 

details refer to .

• The test wiring harness should be used. For 

details refer to .

(1) Disconnect joint connector (CAN1), and measure 

at the wiring harness side.

(2) Measure the resistance between C-04 joint