Mitsubishi L200. Manual - part 813

EXPLANATION ABOUT THE M.U.T.-III CAN BUS DIAGNOSTICS

CONTROLLER AREA NETWORK (CAN)

54C-11

ECU which 
cannot 
communicate 
with the 
M.U.T.-III

Possible 
trouble spot

Logic for narrowing down trouble spot

ECU A

CAN bus line 
(a) and power 
supply system 
to ECU A

ECU A communicates with the 
M.U.T.-III via CAN bus lines (a) 
and (b). The M.U.T.-III judges that 
CAN bus line (b) is normal, 
because it can communicate with 
other ECUs. Possible trouble may 
be present in CAN bus line (a) or 
the power supply system to ECU 
A.

AC204742 AZ

Diagnosis
connector

ECU B

ECU C

ECU D

ECU A

(a)

(b)

(c)

(d)

(e)

(f)

(g)

EXPLANATION ABOUT THE M.U.T.-III CAN BUS DIAGNOSTICS

CONTROLLER AREA NETWORK (CAN)

54C-12

2. If diagnosis code related to CAN communication 

is set as past trouble, isolate opens as described 
below.
NOTE: If you pinpoint trouble spot according to 
diagnosis code, you should use time-out diagno-
sis code. diagnosis code related to failure infor-
mation is set when the data to be set contains an 
error, so CAN bus line itself is probably normal.

NOTE: Time-out diagnosis code codes are stored 
in each ECU memory individually. Therefore, it is 
possible that these diagnosis code codes have 
not been set simultaneously. If the trouble spot 
cannot be found when you diagnose by judging 
from multiple diagnosis code codes, check the 
communication lines between each ECU.

ECU C

CAN bus line 
(g) and power 
supply system 
to ECU C

ECU C communicates with the 
M.U.T.-III via CAN bus lines (b), 
(c), (d) and (g). The M.U.T.-III 
judges that CAN bus lines (b), (c) 
and (d) are normal, because it 
can communicate with ECUs B 
and D. Possible trouble may be 
present in CAN bus line (g) or the 
power supply system to ECU C.

AC204742 BA

ECU B

ECU C

ECU D

ECU A

(a)

(b)

(c)

(d)

(e)

(f)

(g)

Diagnosis
connector

ECU C and 
ECU D

Trouble in 
CAN bus line 
(d)

ECUs C ad D communicate with 
the M.U.T.-III via CAN bus lines 
(b), (c), (d), (e) and (g). The 
M.U.T.-III judges that CAN bus 
lines (b) and (c) are normal, 
because it can communicate with 
ECU B. Possible trouble may be 
present in CAN bus line (d), (e) or 
(g) or the power supply system to 
ECU D or C. CAN bus line (d) is 
shared by ECUs C and D when 
they communicate with the 
M.U.T.-III, so CAN bus line (d) is 
suspected as ultimate cause. 
CAN bus line (g) or (e) and power 
supply systems to ECU C or D 
are also suspected as second 
cause.

AC204742BB

ECU B

ECU C

ECU D

ECU A

(a)

(b)

(c)

(d)

(e)

(f)

(g)

Diagnosis
connector

ECU B and 
ECU D

CAN bus line 
(e) or (f) or 
power supply 
system to ECU 
B or D

ECUs B ad D communicate with 
the M.U.T.-III via CAN bus lines 
(b), (c), (d), (e) and (f). The 
M.U.T.-III judges that CAN bus 
lines (b), (c) and (d) are normal, 
because it can communicate with 
ECU C. Possible trouble may be 
present in CAN bus line (f) or (e) 
or the power supply system to 
ECU B or D.

AC204742 BC

ECU B

ECU C

ECU D

ECU A

(a)

(b)

(c)

(d)

(e)

(f)

(g)

Diagnosis
connector

ECU which 
cannot 
communicate 
with the 
M.U.T.-III

Possible 
trouble spot

Logic for narrowing down trouble spot

Diagnosis 
code to be set

Possible 
trouble spot

Logic for narrowing down trouble spot

Time-out 
diagnosis code 
associated with 
ECU D is stored 
in ECU A, ECU 
B and ECU C.

Trouble in 
CAN bus line 
(e) and power 
supply system 
to ECU D

When time-out diagnosis code 
associated with ECU D is stored 
in ECU A, B and C, or time-out 
diagnosis code associated with 
ECUs A, B and C is stored in 
ECU D, or "bus off" diagnosis 
code is stored in ECU D, CAN 
bus line (e) is suspected. When 
diagnosis code is not stored in 
ECU D, the power supply to ECU 
D is suspected.

AC204742 BD

ECU B

ECU C

ECU D

ECU A

(a)

(b)

(c)

(d)

(e)

(f)

(g)

Diagnosis
connector

Time-out 
diagnosis code 
associated with 
ECUs A, B, C 
and D is stored 
in ECU.
"Bus off" 
diagnosis code 
is stored in ECU 
D.
Time-out 
diagnosis code 
associated with 
ECU A is stored 
in ECUs B, C 
and D.

Trouble in 
CAN bus line 
(a) or (c) and 
power supply 
system to ECU 
A.

When time-out diagnosis code 
associated with ECU A is stored 
in ECUs B, C and D, or time-out 
diagnosis code associated with 
ECUs B, C and D is stored in 
ECU A, or "bus off" diagnosis 
code is stored in ECU A, CAN 
bus line (a) or (c) is suspected. 
When diagnosis code is not 
stored in ECU A, the power 
supply to ECU A is suspected.

AC204742 BF

ECU B

ECU C

ECU D

ECU A

(a)

(b)

(c)

(d)

(e)

(f)

(g)

Diagnosis
connector

Time-out 
diagnosis code 
associated with 
ECUs B, C and 
D is stored in 
ECU A.
"Bus off" 
diagnosis code 
is stored in ECU 
A.
Time-out 
diagnosis code 
codes 
associated with 
ECUs C and D 
are stored in 
ECU A and 
ECU B.

Trouble in 
CAN bus line 
(d)

If time-out diagnosis code codes 
associated with ECUs C and D 
are stored in ECUs A and B, or 
time-out codes associated with 
ECUs A and B are stored in 
ECUs C and D, CAN bus line (d) 
is suspected. CAN bus line (g) or 
(e) and power supply systems to 
ECU C or D are also suspected 
as second cause.

AC204742BQ

ECU B

ECU C

ECU D

ECU A

(a)

(b)

(c)

(d)

(e)

(f)

(g)

Diagnosis
connector

Time-out 
diagnosis code 
codes 
associated with 
ECUs A and B 
are stored in 
ECU C and 
ECU D.

EXPLANATION ABOUT THE M.U.T.-III CAN BUS DIAGNOSTICS

CONTROLLER AREA NETWORK (CAN)

54C-13

TROUBLESHOOTING

CONTROLLER AREA NETWORK (CAN)

54C-14

TROUBLESHOOTING

CAN BUS DIAGNOSTICS TABLE

M1548300202222

This diagnosis applies only to the CAN bus lines. If a 
different system is defective, proceed to the applica-
ble diagnosis section for each system. Observe the 
diagnosis procedure below only when the CAN bus 
line is defective.

CAUTION

During diagnosis, a diagnosis code associated with another system may be set when the ignition 
switch is turned on with connector(s) disconnected. After completing the repair, confirm all systems 
for diagnosis code(s). If diagnosis code(s) are set, erase them all.

M.U.T.-III screen

Diagnosis detail

Referenc
e page

(The ECUs that are not adopted are not displayed.)

Comment

ACA01245

: Red section on screen

AB

ETACS

DISPLAY

ABS/ASC

SAS

YR/G

A/C

AT

ENGINE

JC

JC

M.U.T.

Short circuit to 
battery in red 
displayed area is 
estimated.

Diagnosis Item 1
Diagnose shorts in 
the power supply 
to CAN bus line

P.54C-20

Earthing in red 
displayed area is 
estimated.

Diagnosis Item 2
Diagnose shorts in 
the earth to CAN 
bus line

P.54C-42

Short circuit 
between CAN_H 
and CAN_L in 
red displayed 
area is 
estimated.

Diagnosis Item 3
Diagnose shorts 
between CAN_H 
and L lines

P.54C-64

ACA01245

: Red section on screen

AC

ETACS

DISPLAY

ABS/ASC

SAS

YR/G

A/C

AT

ENGINE

JC

JC

M.U.T.

Disconnection in 
red displayed 
area is 
estimated.

Diagnosis Item 4
Diagnose the 
terminator 
resistors

P.54C-81