Mitsubishi 380. Manual - part 655

DIAGNOSIS

CONTROLLER AREA NETWORK (CAN)

54C-31

CAN BUS DIAGNOSTICS

DIAGNOSTIC ITEM 1: Diagnose shorts in the power supply to CAN bus line <Vehicles without 
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

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)

DIAGNOSIS

CONTROLLER AREA NETWORK (CAN)

54C-32

.

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 ENGINE-ECU may be defective

• The A/T-ECU may be defective

16DB474A

C-218 (GR)

CONNECTOR: C-218

HARNESS SIDE

JUNCTION BLOCK
(REAR VIEW)

DIAGNOSIS

CONTROLLER AREA NETWORK (CAN)

54C-33

DIAGNOSIS

Required Special Tools:

• MB991223: Harness Set

• MB991219: Inspection Test Harness

STEP 1. Check ENGINE-ECU connector B-21, combination 
meter connector C-101 and data link connector C-125 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-4

.

Q: Are ENGINE-ECU connector B-21, combination meter 

connector C-101 and data link connector C-125 in good 
condition?
YES : Go to Step 2.
NO :  Repair the damaged parts.

16DB400A

COVER

ENGINE
CONTROL
UNIT

AIR
CLEANER

16DB475A

CONNECTORS: C-101, C-125

C-101

C-125

C-125 (B)

C-101 HARNESS SIDE

DIAGNOSIS

CONTROLLER AREA NETWORK (CAN)

54C-34

STEP 2. Check the CAN_H-side bus line (communication 

line including ECUs) for a short to the power supply. 

Measure the voltage at data link connector C-125.

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 ENGINE-ECU connector B-21 and combination 

meter connector C-101, and measure the voltage at the 
harness side of data link connector C-125.

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

16DB400A

COVER

ENGINE
CONTROL
UNIT

AIR
CLEANER

16DB475A

CONNECTORS: C-101, C-125

C-101

C-125

C-125 (B)

C-101 HARNESS SIDE