Mitsubishi Galant 9G. Manual — part 1226

EXPLANATION ABOUT THE SCAN TOOL (MUT-III) CAN BUS DIAGNOSTICS

TSB Revision

CONTROLLER AREA NETWORK (CAN)

54C-8

AC204741

DATA LINK
CONNECTOR

ECU B

ECU C

ECU D

ECU A

(a)

(b)

(c)

(d)

(e)

(f)

(g)

AC

REFERENCE CIRCUIT

ECU WHICH
CAN NOT
COMMUNICATE
WITH THE
MUT-III

POSSIBLE
TROUBLE
SPOT

LOGIC FOR DETERMINING DOWN TROUBLE SPOT

ECU A

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

ECU A communicates with the
MUT-III via CAN bus lines (a) and
(b). The MUT-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.

ECU C

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

ECU C communicates with the
MUT-III via CAN bus lines (b), (c),
(d) and (g). The MUT-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 AZ

DATA LINK
CONNECTOR

ECU B

ECU C

ECU D

ECU A

(a)

(b)

(c)

(d)

(e)

(f)

(g)

AC204742 BA

DATA LINK

CONNECTOR

ECU B

ECU C

ECU D

ECU A

(a)

(b)

(c)

(d)

(e)

(f)

(g)

EXPLANATION ABOUT THE SCAN TOOL (MUT-III) CAN BUS DIAGNOSTICS

TSB Revision

CONTROLLER AREA NETWORK (CAN)

54C-9

2. If DTC code related to CAN communication is set

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

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

ECU C and
ECU D

Trouble in
CAN bus line
(d)

ECUs C and D communicate with
the MUT-III via CAN bus lines (b),
(c), (d), (e) and (g). The MUT-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. CAN bus line (d) is shared by
ECUs C and D when they
communicate with the MUT-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.

ECU B and
ECU D

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

ECUs C and D communicate with
the MUT-III via CAN bus lines (b),
(c), (d), (e) and (g). The MUT-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.

ECU WHICH
CAN NOT
COMMUNICATE
WITH THE
MUT-III

POSSIBLE
TROUBLE
SPOT

LOGIC FOR DETERMINING DOWN TROUBLE SPOT

AC204742 BB

DATA LINK

CONNECTOR

ECU B

ECU C

ECU D

ECU A

(a)

(b)

(c)

(d)

(e)

(f)

(g)

AC204742 BC

DATA LINK

CONNECTOR

ECU B

ECU C

ECU D

ECU A

(a)

(b)

(c)

(d)

(e)

(f)

(g)

EXPLANATION ABOUT THE SCAN TOOL (MUT-III) CAN BUS DIAGNOSTICS

TSB Revision

CONTROLLER AREA NETWORK (CAN)

54C-10

DTC CODE TO
BE SET

POSSIBLE
TROUBLE
SPOT

LOGIC FOR DETERMINING TROUBLE SPOT

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

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

AC204742 BD

DATA LINK

CONNECTOR

ECU B

ECU C

ECU D

ECU A

(a)

(b)

(c)

(d)

(e)

(f)

(g)

EXPLANATION ABOUT THE SCAN TOOL (MUT-III) CAN BUS DIAGNOSTICS

TSB Revision

CONTROLLER AREA NETWORK (CAN)

54C-11

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

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

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

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

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

Trouble in
CAN bus line
(d)

If time-out DTC 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.

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

DTC CODE TO
BE SET

POSSIBLE
TROUBLE
SPOT

LOGIC FOR DETERMINING TROUBLE SPOT

AC204742 BE

DATA LINK

CONNECTOR

ECU B

ECU C

ECU D

ECU A

(a)

(b)

(c)

(d)

(e)

(f)

(g)

AC204742 BF

DATA LINK

CONNECTOR

ECU B

ECU C

ECU D

ECU A

(a)

(b)

(c)

(d)

(e)

(f)

(g)

AC204742BG

DATA LINK

CONNECTOR

ECU B

ECU C

ECU D

ECU A

(a)

(b)

(c)

(d)

(e)

(f)

(g)