Mitsubishi Grandis. Manual — part 479

EXPLANATION ABOUT THE MUT-III CAN BUS DIAGNOSTICS

CONTROLLER AREA NETWORK (CAN)

54D-14

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
diagnosis code. diagnosis 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 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
can not 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
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.

ECU C and
ECU D

Trouble in
CAN bus line
(d)

ECUs C ad 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 ad 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
cannot
communicate
with the
MUT-III

Possible
trouble spot

Logic for narrowing down trouble spot

AC204742 BA

DATA LINK

CONNECTOR

ECU B

ECU C

ECU D

ECU A

(a)

(b)

(c)

(d)

(e)

(f)

(g)

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 MUT-III CAN BUS DIAGNOSTICS

CONTROLLER AREA NETWORK (CAN)

54D-15

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.

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

DIAGNOSIS

CONTROLLER AREA NETWORK (CAN)

54D-16

DIAGNOSIS

CAN BUS DIAGNOSTICS TABLE

M1548300200077

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

Time-out
diagnosis 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 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.

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.

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

Diagnosis
code to be set

Possible
trouble spot

Logic for narrowing down 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)

DIAGNOSIS

CONTROLLER AREA NETWORK (CAN)

54D-17

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.

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