Mitsubishi 380. Manual - part 738

DIAGNOSIS

CONTROLLER AREA NETWORK (CAN)

54C-363

(4) Measure the resistance between A/T-ECU connector B-19 

terminal 5 and ENGINE-ECU connector B-21 terminal 86.

OK: 2 ohms or less

(5) Measure the resistance between A/T-ECU connector B-19 

terminal 4 and ENGINE-ECU connector B-21 terminal 64.

OK: 2 ohms or less

NOTE: when diagnosing CAN-BUS on vehicles with 
manual transmission (M/T), disregard A/T-ECU and it’s wir-
ing circuits and check between ABS-ECU and 
ENGINE-ECU only.

CAUTION

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

P.54C-5

.

Q: Do all the resistances measure 2 ohms or less?

YES  : If all the resistances measure 2 ohms or less, go to 

Step 29.

NO  :  If either of the resistances measures more than 2 

ohms or all the resistances measure more than 2 
ohms, repair the wiring harness between A/T-ECU 
connector B-19 and the ENGINE-ECU connector 
B-21. 

16DB510A

HARNESS SIDE: B-19

TEST
HARNESS

TEST
HARNESS

HARNESS SIDE:  B-21

16DB511A

HARNESS SIDE: B-19

TEST
HARNESS

TEST
HARNESS

HARNESS SIDE:  B-21

DIAGNOSIS

CONTROLLER AREA NETWORK (CAN)

54C-364

STEP 29. Check the CAN bus lines inside the A/T-ECU. 
Measure the resistance at A/T-ECU connector B-19.

NOTE: when diagnosing CAN-BUS on vehicles with 
manual transmission (M/T), disregard A/T-ECU and it’s wir-
ing circuits and check between ABS-ECU and 
ENGINE-ECU only.

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, and measure the 

resistance at the component side of A/T-ECU connector 
B-19.

(2) Turn the ignition switch to the "LOCK" (OFF) position.

CAUTION

Disconnect the negative battery terminal. For details refer 
to 

P.54C-4

.

(3) Disconnect the negative battery terminal.

(4) Measure the resistance between A/T-ECU connector B-19 

terminals 5 and 14.

OK: 2 ohms or less

(5) Measure the resistance between A/T-ECU connector B-19 

terminals 4 and 13.

OK: 2 ohms or less

CAUTION

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

P.54C-5

.

Q: Do all the resistances measure 2 ohms or less?

YES  : If all the resistances measure 2 ohms or less, or go 

to Step 30 power supply to the ENGINE-ECU may be 
suspected. Diagnose the engine. Refer to GROUP 
13A, MPI diagnosis 

P.13A-571

 <3.8L engine>.

NO  :  If either of the resistances measures more than 2 

16DB480A

COVER

ENGINE

CONTROL

UNIT

AIR

CLEANER

A/T

CONTROL

UNIT

16DB518A

TEST
HARNESS

TEST
HARNESS

COMPONENT SIDE:  B-19

16DB519A

TEST
HARNESS

TEST
HARNESS

COMPONENT SIDE:  B-19

DIAGNOSIS

CONTROLLER AREA NETWORK (CAN)

54C-365

ohms or all the resistances measure more than 2 
ohms, replace the A/T-ECU.

STEP 30. Using diagnostic tool MB991958, diagnose the 
CAN bus line (Disconnect A/T-ECU connector B-19, and 
check the A/T-ECU system).

NOTE: when diagnosing CAN-BUS on vehicles with 
manual transmission (M/T), disregard A/T-ECU and it’s wir-
ing circuits and check between ABS-ECU and 
ENGINE-ECU only.
(1) Disconnect A/T-ECU connector B-19.
(2) Turn the ignition switch to the "ON" position.

(3) Diagnose CAN bus lines, and check if the MUT-III screen is 

as shown in the illustration.

NOTE: When diagnosing CAN-BUS on vehi-

cles with manual transmission (M/T), disregard 
A/T-ECU and it’s wiring circuits and measure 
between ABS-ECU and ENGINE-ECU only.

NOTE: When diagnosing CAN-BUS on vehicles 
not equipped with a multi-centre display, disre-
gard the multi-centre display and it’s wiring cir-
cuits.

16DB480A

COVER

ENGINE

CONTROL

UNIT

AIR

CLEANER

A/T

CONTROL

UNIT

16DB615A

: Red section on screen

ENGINE

ECU

METER

-ECU

ETACS

-ECU

AC-ECU

SRS-ECU

C.DISPLAY

MUT

J/C

ABS-ECU

A/T-ECU

DIAGNOSIS

CONTROLLER AREA NETWORK (CAN)

54C-366

(4) Turn the ignition switch to the "LOCK" (OFF) position.
(5) Check A/T-ECU connector B-19.

Q: Does the MUT-III screen correspond to the illustration?

YES  : If the MUT-III screen corresponds to the illustration, 

power supply to the A/T-ECU may be suspected  
Diagnose the A/T-ECU system.

NO  :  If the MUT-III screen does not correspond to the 

illustration, refer to diagnostics item 3: Check the 
CAN_L and H lines for a short circuit (Refer to 

P.54C-239

).