Mitsubishi Lancer (4A9 engine). Manual — part 254

ACA00887

BF

Connector: C-301 <RHD>
ETACS-ECU

TROUBLESHOOTING

CONTROLLER AREA NETWORK (CAN)

54C-40

FUNCTION
If a short to earth is present in the CAN-C lines, this
diagnosis result will be set.

TROUBLE JUDGEMENT CONDITIONS
If diagnosis code U1120 is set, the ETACS-ECU
determines that there is a failure.

TROUBLESHOOTING HINTS

• Malfunction of the connector (short to earth inside

connector)

• Malfunction of the wiring harness (short to earth

in the CAN-C main or sub bus lines)

• Malfunction of the ECU (ETACS-ECU, or ECUs

on CAN-C lines failed)

DIAGNOSIS PROCEDURE

STEP 1. Check the wiring harness between C-301
ETACS-ECU connector and C-03 joint connector
(CAN2) 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 (CAN2), and measure

at the wiring harness side.

(2) Resistance between C-03 joint connector (CAN2)

terminal No.11 and body earth.

OK: 1 k

Ω or more

(3) Resistance between C-03 joint connector (CAN2)

terminal No.22 and body earth.

OK: 1 k

Ω or more

Q: Is the check result normal?

YES <vehicles with ASC or AFS> :

Go to Step 2.

YES <vehicles without ASC and without AFS with
reversing sensor system> :

Go to Step 3.

YES <vehicles without ASC and without AFS
without reversing sensor system> :

Go to Step 4.

NO :

Go to Step 12.

STEP 2. Check the wiring harness between C-211
steering wheel sensor connector and C-03 joint
connector (CAN2) 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 (CAN2), and measure

at the wiring harness side.

(2) Resistance between C-03 joint connector (CAN2)

terminal No.9 and body earth.

OK: 1 k

Ω or more

(3) Resistance between C-03 joint connector (CAN2)

terminal No.20 and body earth.

OK: 1 k

Ω or more

Q: Is the check result normal?

YES <vehicles with reversing sensor system> :

Go

to Step 3.

YES <vehicles without reversing sensor system> :

Go to Step 4.

NO :

Go to Step 10.

STEP 3. Check the wiring harness between C-40
corner sensor/back sensor-ECU connector and
C-03 joint connector (CAN2) 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 (CAN2), and measure

at the wiring harness side.

(2) Resistance between C-03 joint connector (CAN2)

terminal No.7 and body earth.

OK: 1 k

Ω or more

(3) Resistance between C-03 joint connector (CAN2)

TROUBLESHOOTING

CONTROLLER AREA NETWORK (CAN)

54C-41

terminal No.18 and body earth.

OK: 1 k

Ω or more

Q: Is the check result normal?

YES <vehicles with AFS> :

Go to Step 4.

YES <vehicles without AFS> :

Go to Step 5.

NO :

Go to Step 11.

STEP 4. Check the wiring harness between C-14
headlamp automatic levelling-ECU connector
and C-124 joint connector (CAN3) 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 (CAN3), and measure

at the wiring harness side.

(2) Resistance between C-124 joint connector

(CAN3) terminal No.7 <Petrol> or 8 <Diesel> and
body earth

OK: 1 k

Ω or more

(3) Resistance between C-124 joint connector

(CAN3) terminal No.18 <Petrol> or 19 <Diesel>
and body earth

OK: 1 k

Ω or more

Q: Is the check result normal?

YES :

Go to Step 5.

NO :

Go to Step 13.

STEP 5. Check the wiring harness between A-04
ABS-ECU connector <vehicles without ASC> or
A-58 ASC-ECU connector <vehicles with ASC>
and C-124 joint connector (CAN3) 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 (CAN3), and measure

at the wiring harness side.

(2) Resistance between C-124 joint connector

(CAN3) terminal No.9 and body earth

OK: 1 k

Ω or more

(3) Resistance between C-124 joint connector

(CAN3) terminal No.20 and body earth

OK: 1 k

Ω or more

Q: Is the check result normal?

YES <A/T or CVT> :

Go to Step 6.

YES <M/T (vehicles with electric power steering) > :

Go to Step 7.

YES <M/T (vehicles without electric power steering
and with automatic stop & go (AS&G) system)> :

Go to Step 8.

YES <M/T (vehicles without electric power steering
and without automatic stop & go (AS&G) system)>
:

Go to Step 9.

NO :

Go to Step 14.

STEP 6. Check the wiring harness between C-32
A/T-ECU connector <A/T> or C-35 CVT-ECU
connector <CVT> and C-124 joint connector
(CAN3) 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 (CAN3), and measure

at the wiring harness side.

(2) Resistance between C-124 joint connector

(CAN3) terminal No.8 and body earth

OK: 1 k

Ω or more

(3) Resistance between C-124 joint connector

(CAN3) terminal No.19 and body earth

OK: 1 k

Ω or more

Q: Is the check result normal?

YES <vehicles with electric power steering> :

Go

to Step 7.

YES <vehicles without electric power steering and
with automatic stop & go (AS&G) system> :

Go to

Step 8.

YES <vehicles without electric power steering and
without automatic stop & go (AS&G) system> :

Go

to Step 9.

NO :

Go to Step 15.

TROUBLESHOOTING

CONTROLLER AREA NETWORK (CAN)

54C-42

STEP 7. Check the wiring harness between C-114
electric power steering-ECU connector and C-
124 joint connector (CAN3) 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 (CAN3), and measure

at the wiring harness side.

(2) Resistance between C-124 joint connector

(CAN3) terminal No.6 <Petrol> or 7 <Diesel> and
body earth

OK: 1 k

Ω or more

(3) Resistance between C-124 joint connector

(CAN3) terminal No.17 <Petrol> or 18 <Diesel>
and body earth

OK: 1 k

Ω or more

Q: Is the check result normal?

YES <vehicles with automatic stop & go (AS&G)
system> :

Go to Step 8.

YES <vehicles without automatic stop & go (AS&G)
system> :

Go to Step 9.

NO :

Go to Step 16.

STEP 8. Check the wiring harness between C-64
AS&G-ECU connector and C-124 joint connector
(CAN3) 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 (CAN3), and measure

at the wiring harness side.

(2) Resistance between C-124 joint connector

(CAN3) terminal No.16 <Petrol> or 17 <Diesel>
and body earth

OK: 1 k

Ω or more

(3) Resistance between C-124 joint connector

(CAN3) terminal No.5 <Petrol> or 6 <Diesel> and
body earth

OK: 1 k

Ω or more

Q: Is the check result normal?

YES :

Go to Step 9.

NO :

Go to Step 17.

STEP 9. Check the wiring harness between B-09
<Petrol> or B-40 <Diesel> engine-ECU connector
and C-124 joint connector (CAN3) 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 (CAN3), and measure

at the wiring harness side.

(2) Resistance between C-124 joint connector

(CAN3) terminal No.10 and body earth

OK: 1 k

Ω or more

(3) Resistance between C-124 joint connector

(CAN3) terminal No.21 and body earth

OK: 1 k

Ω or more

Q: Is the check result normal?

YES :

Check C-127 intermediate connector, and

repair if necessary. If the intermediate
connector is in good condition, repair the
wiring harness between C-03 joint
connector (CAN2) and C-124 joint
connector (CAN3).

NO :

Go to Step 18.

TROUBLESHOOTING

CONTROLLER AREA NETWORK (CAN)

54C-43

STEP 10. M.U.T.-III CAN bus diagnostics
(checking the steering wheel sensor for internal
short to earth)

CAUTION

Strictly observe the specified wiring harness
repair procedure. For details refer to .
Disconnect C-211 steering wheel sensor connector,
and diagnose the CAN bus line.

ACB01921AB

M.U.T.

JC

JC

SAS

KOS/
WCM

SRS

A/C

AUDIO

METER

AT/

CVT

EPS

ENGINE

ETACS

ABS/

ASC

MMCS

: Red section on screen

AS&G

Levelling

Cor ner

JC

OK: The display of the M.U.T.-III is as shown
in the figure.

Q: Does M.U.T.-III screen correspond to the

illustration?
YES :

Repair the wiring harness between C-211

steering wheel sensor connector and C-03
joint connector (CAN2).

NO :

Check the steering wheel sensor connector,
and repair if necessary. If the steering wheel
sensor connector is in good condition,
replace the steering wheel sensor.

STEP 11. M.U.T.-III CAN bus diagnostics
(checking the corner sensor/back sensor-ECU
for internal short to earth)

CAUTION

Strictly observe the specified wiring harness
repair procedure. For details refer to .
Disconnect C-40 corner sensor/back sensor-ECU
connector, and diagnose the CAN bus line.

ACB01921AB

M.U.T.

JC

JC

SAS

KOS/
WCM

SRS

A/C

AUDIO

METER

AT/

CVT

EPS

ENGINE

ETACS

ABS/

ASC

MMCS

: Red section on screen

AS&G

Levelling

Cor ner

JC

OK: The display of the M.U.T.-III is as shown
in the figure.

Q: Does M.U.T.-III screen correspond to the

illustration?
YES :

Repair the wiring harness between C-125

corner sensor/back sensor-ECU connector
and C-03 joint connector (CAN2).

NO :

Check the corner sensor/back sensor-ECU
connector, and repair if necessary. If the
corner sensor/back sensor-ECU connector
is in good condition, replace the corner
sensor/back sensor-ECU.

STEP 12. Check the wiring harness between C-
301 ETACS-ECU connector and C-03 joint
connector (CAN2) 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 .

• Strictly observe the specified wiring harness

repair procedure. For details refer to .

(1) Disconnect ETACS-ECU connector and joint

connector (CAN2), and measure at the wiring
harness side.

(2) Measure the resistance between C-03 joint

connector (CAN2) terminal No.11 and body earth.