Mitsubishi Evolution X. Manual - part 1098

DIAGNOSIS

TSB Revision

CONTROLLER AREA NETWORK (CAN)

54C-27

CAN BUS DIAGNOSTICS

DIAGNOSTIC ITEM 1: Diagnose when the scan tool cannot receive the data sent by ETACS-ECU.

CAUTION

When servicing a CAN bus line, ground yourself by touching a metal object such as an unpainted 
water pipe. If you fail to do so, a component connected to the CAN bus line may be damaged.

.

FUNCTION

When the CAN bus diagnosis is carried out, the scan 
tool communicates with the ETACS-ECU. If a com-
munication flag is not set for the ETACS-ECU, the 
ETACS-ECU will be diagnosed as a communication 
error.

.

TROUBLE JUDGEMENT CONDITIONS

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

.

TROUBLESHOOTING HINTS

• Malfunction of the connector (data link connector 

or ETACS-ECU connector improperly connected)

• Malfunction of the wiring harness (open circuit, 

short to ground, short to power supply between 
the data link connector and the ETACS-ECU con-
nector, line-to-line short, or power supply to the 
ETACS-ECU)

• Malfunction of ETACS-ECU

Diagnosis CAN Communication Circuit

ETACS-ECU

DATA LINK
CONNECTOR

CAN DRIVE
CIRCUIT

INTERFACE
CIRCUIT

FRONT SIDE

AC708950BT

Connector: C-40

C-40 (B)

 

AC708972AY

Connector: C-301

ETACS-ECU

DIAGNOSIS

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CONTROLLER AREA NETWORK (CAN)

54C-28

DIAGNOSIS

Required Special Tools:

• MB991223: Harness Set

• MB992006: Extra Fine Probe

• MB991958: Scan Tool (M.U.T.-III Sub Assembly)

• MB991824: Vehicle Communication Interface (V.C.I.)

• MB991827: M.U.T.-III USB Cable

• MB991910: M.U.T.-III Main Harness A

STEP 1. Check data link connector C-40 and ETACS-ECU 
connector C-301 for loose, corroded or damaged 
terminals, or terminals pushed back in the connector.

CAUTION

The strand end of the twisted wire should be within 10 cm 
(4 inches) from the connector. For details refer to 

P.54C-7

.

Q: Are data link connector C-40 and ETACS-ECU connector 

C-301 in good condition?
YES : Go to Step 2.
NO :  Repair the damaged parts.

STEP 2. Check the wiring harness between data link 
connector C-40 and ETACS-ECU connector C-301 for open 
circuit.

CAUTION

Strictly observe the specified wiring harness repair proce-
dure. For details refer to 

P.54C-7

.

(1) Disconnect the scan tool and ETACS-ECU connector 

C-301, and check the wiring harness.

(2) Check the wiring harness between data link connector C-40 

(terminal 6) and ETACS-ECU connector C-301 (terminal 5) 
<CAN_H>

OK: Continuity exists (2 

Ω or less)

(3) Check the wiring harness between data link connector C-40 

(terminal 14) and ETACS-ECU connector C-301 (terminal 
4) <CAN_L>

OK: Continuity exists (2 

Ω or less)

Q: Is the wiring harness between data link connector C-40 

and ETACS-ECU connector C-301 in good condition?
YES : Go to Step 3.
NO :  Repair the wiring harness between data link 

connector C-40 and ETACS-ECU connector C-301.

AC709707

TEST 
HARNESS

Harness side: C-40

AE

TEST HARNESS

Harness side: C-301

AC709707

AC709707

TEST 
HARNESS

Harness side: C-40

AF

Harness side: C-301

TEST HARNESS

DIAGNOSIS

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CONTROLLER AREA NETWORK (CAN)

54C-29

STEP 3. Check the wiring harness between data link 
connector C-40 and ETACS-ECU connector C-301 for a 
short to ground. Measure the resistance at data link 
connector C-40.

CAUTION

Disconnect the negative battery terminal. For details refer 
to 

P.54C-7

.

CAUTION

A digital multimeter should be used. For details refer to 

P.54C-7

.

CAUTION

The test wiring harness should be used. For details refer to 

P.54C-7

.

(1) Disconnect the scan tool and ETACS-ECU connector 

C-301, and measure the resistance at the wiring harness 
side of data link connector C-40.

(2) Measure the resistance between data link connector 

terminal 6 and body ground. <CAN_H>

OK: 1 kilo ohm or more

(3) Measure the resistance between data link connector 

terminal 14 and body ground. <CAN_L>

OK: 1 kilo ohm or more

Q: Do all the resistances measure 1 kilo ohm or more?

YES : Go to Step 4.
NO :  Repair the wiring harness between data link 

connector C-40 and ETACS-ECU connector C-301.

STEP 4. Check the wiring harness between data link 
connector C-40 and ETACS-ECU connector C-301 for a 
short to the power supply. Measure the voltage at data link 
connector C-40.
(1) Disconnect the scan tool and ETACS-ECU connector 

C-301, and measure the resistance at the wiring harness 
side of data link connector C-40.

(2) Turn the ignition switch to the "ON" position.

AC709707

TEST 
HARNESS

Harness side: C-40

AB

AC709707

Harness side: C-40

AC

TEST 
HARNESS

DIAGNOSIS

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CONTROLLER AREA NETWORK (CAN)

54C-30

(3) Measure the voltage between data link connector terminal 6 

and body ground. <CAN_H>

OK: 5 volts or less

(4) Measure the voltage between data link connector terminal 

14 and body ground. <CAN_L>

OK: 5 volts or less

Q: Do all the voltage measure 5 volts or less?

YES : Go to Step 5.
NO :  Repair the wiring harness between data link 

connector C-40 and ETACS-ECU connector C-301.

STEP 5. Check the wiring harness between data link 
connector C-40 and ETACS-ECU connector C-301 for 
line-to-line short. Measure the resistance at data link 
connector C-40.
(1) Disconnect the scan tool and ETACS-ECU connector 

C-301, and measure the resistance at the wiring harness 
side of data link connector C-40.

(2) Measure the resistance between data link connector 

terminal 6 and 14.

OK: No continuity

Q: Is the check result normal?

YES : Go to Step 6.
NO :  Repair the wiring harness between data link 

connector C-40 and ETACS-ECU connector C-301.

AC709708

TEST 
HARNESS

Harness side: C-40

AB

AC709708

Harness side: C-40

AC

TEST 
HARNESS

AC709707

Harness side: C-40

AD

TEST 
HARNESS

TEST 
HARNESS