Mitsubishi 380. Manual - part 667

DIAGNOSIS

CONTROLLER AREA NETWORK (CAN)

54C-79

(3) Measure the voltage between ENGINE-ECU connector 

terminal 86 and body ground.

OK: 1.0 V or less

CAUTION

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

P.54C-5

.

Q: Does the voltage measure 1.0 V or less?

YES : If the voltage measures 1.0 V or less, go to Step 47.
NO :  If the voltage measures more than 1.0 V, repair the 

wiring harness between ENGINE-ECU connector and 
A/T-ECU connector.

STEP 47. Check the CAN_L line inside the A/T-ECU for a 
short to the power supply. Measure the voltage at A/T-ECU 
connector B-19 for loose, corroded or damaged terminals, 
or terminals pushed back in the connector.

CAUTION

A digital multimeter should be used. For details refer to 

P.54C-4

.

CAUTION

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

P.54C-4

.

(1) Disconnect A/T-ECU connector B-19.
NOTE: When diagnosing CAN BUS on vehicles with 
manual transmission (M/T) please disregard A/T ECU and 
its circuits.

16DB478A

CONNECTOR: C-121

HARNESS SIDE

C-121 (Y)

48

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

38

39

40

41

42

43

44

45

46

47

16DB480A

COVER

ENGINE
CONTROL
UNIT

AIR
CLEANER

A/T
CONTROL
UNIT

DIAGNOSIS

CONTROLLER AREA NETWORK (CAN)

54C-80

(2) Connect special tool MB992045 (A/T check harness) to the 

A/T-ECU and the wiring harness, and measure the voltage 
at special tool MB992045 (A/T check harness).

(3) Turn the ignition switch to the "ON" position.
(4) Measure the voltage between special tool MB992045 (A/T 

check harness) connector terminal 14 and body ground.

OK: 4.0 V or less

Q: Does the voltage measure 4.0 V or less?

YES : If the voltage measures 4.0 V or less, diagnose CAN 

bus lines thoroughly by referring to 

P.54C-323

.

NO :  If the voltage measures more than 4.0 V, replace the 

A/T-ECU.

NOTE: When diagnosing CAN BUS on vehicles with 
manual transmission (M/T) please disregard A/T ECU and 
its circuits.

16DB488A

TEST
HARNESS

SPECIAL TOOL
MB992045

A/T-
ECU

MEASURE AT THIS CONNECTOR

SPECIAL TOOL MB992045 
CONNECTOR

DIAGNOSIS

CONTROLLER AREA NETWORK (CAN)

54C-81

DIAGNOSTIC ITEM 2: Diagnose shorts in the power supply to CAN bus line <Vehicles with 
multi-center display >

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 con-
nected to the CAN bus line may be damaged.

16DB402A

A-02 (GR)

CONNECTOR: A-02 

A-02 HARNESS CONNECTOR:

16DB407A

COVER

ENGINE
CONTROL
UNIT

AIR
CLEANER

A/T
CONTROL
UNIT

16DB489A

CONNECTORS: C-05, C-15, C-121

C-121 (Y)

C-15 (B)

C-05 (B)

16DB472A

C-101

C-125 (B)

C-29

C-02

CONNECTORS: C-02, C-29, C-101, C-125

16DB473A

CONNECTORS: C-15, C-121

C-121 (Y)

C-15 (B)

16DB474A

C-218 (GR)

CONNECTOR: C-218

HARNESS SIDE

JUNCTION BLOCK
(REAR VIEW)

DIAGNOSIS

CONTROLLER AREA NETWORK (CAN)

54C-82

.

TROUBLE JUDGMENT

A short to the power supply may be present when the 
voltage between the CAN bus line (CAN_L or 
CAN_H) and body ground is more than 4.0 V. In this 
condition, an abnormal voltage may be measured at 
CAN_L and CAN_H lines.

.

COMMENTS ON TROUBLE SYMPTOM

The wiring harness wire or connectors may have 
loose, corroded, or damage terminals, or terminals 
pushed back in the connector, or a ECU may be 
defective.

.

TROUBLESHOOTING HINTS

• Refer to circuit diagrams GROUP-

90

• Refer to configuration diagrams GROUP-

80

• The wiring harness or connectors may have 

loose, corroded, or damaged terminals, or termi-
nals pushed back in the connector

• The ETACS-ECU may be defective

• The combination meter may be defective

• The A/C-ECU may be defective

• The ABS-ECU may be defective

• The SRS-ECU may be defective

• The multi-centre display unit (middle-grade type 

may be defective

• The ENGINE-ECU may be defective

• The A/T-ECU may be defective