Mitsubishi Evolution X. Manual - part 1094

EXPLANATION ABOUT THE SCAN TOOL (M.U.T.-III) CAN BUS DIAGNOSTICS

TSB Revision

CONTROLLER AREA NETWORK (CAN)

54C-11

ECU C

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

The ECU C communicates with 
scan tool MB991958 via CAN 
bus lines (b), (c), (d) and (g). 
Scan tool MB991958 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 and D communicate 
with scan tool MB991958 via 
CAN bus lines (b), (c), (d), (e) 
and (g). Scan tool MB991958 
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 C and ECU D. 
CAN bus line (d) is shared by 
ECUs C and D when they 
communicate with scan tool 
MB991958, 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) and 
power supply 
system to 
ECU B or D

ECUs B and D communicate 
with scan tool MB991958 via 
CAN bus lines (b), (c), (d), (e) 
and (f). Scan tool MB991958 
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) and power supply system to 
ECU B or D are also suspected 
as second cause.

ECU which 
cannot 
communicate 
with the scan 
tool

Possible 
trouble spot

Logic for narrowing down trouble spot

AC204742BI

ECU B

ECU C

ECU D

ECU A

(a)

(b)

(c)

(d)

(e)

(f)

(g)

(h)

ETACS-ECU
(Gateway)

Data link  
connector

AC204742BJ

ECU B

ECU C

ECU D

ECU A

(a)

(b)

(c)

(d)

(e)

(f)

(g)

(h)

ETACS-ECU
(Gateway)

Data link 
connector

AC204742BK

ECU B

ECU C

ECU D

ECU A

(a)

(b)

(c)

(d)

(e)

(f)

(g)

(h)

ETACS-ECU
(Gateway)

Data link 
connector

EXPLANATION ABOUT THE SCAN TOOL (M.U.T.-III) CAN BUS DIAGNOSTICS

TSB Revision

CONTROLLER AREA NETWORK (CAN)

54C-12

2. Pinpoint possible trouble spot according to 

diagnostic trouble code
If diagnostic trouble code related to CAN 
communication is set as past trouble, isolate 
opens as described below.
NOTE: If you pinpoint trouble spot according to 
diagnostic trouble code, you should use time-out 
diagnostic trouble code. Diagnostic trouble 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 diagnostic trouble codes are 
stored in each ECU memory individually. There-
fore, it is possible that these diagnostic trouble 
codes have not been set simultaneously. If the 
trouble spot cannot be found when you diagnose 
by judging from multiple diagnostic trouble codes, 
check the communication lines between each 
ECU.

All ECU 
(except 
ETACS-ECU)

CAN bus line 
(b)

The other ECUs except the 
ETACS-ECU use CAN bus 
lines (b) and (h) when they 
communicate with scan tool 
MB991958. It must be assumed 
that CAN bus line (b) is 
defective since the 
ETACS-ECU can communicate 
with scan tool MB991958.

ECU which 
cannot 
communicate 
with the scan 
tool

Possible 
trouble spot

Logic for narrowing down trouble spot

AC204742BP

ECU B

ECU C

ECU D

ECU A

(a)

(b)

(c)

(d)

(e)

(f)

(g)

(h)

ETACS-ECU
(Gateway)

Data link 
connector

Diagnostic 
trouble code to 
be set

Possible 
trouble spot

Logic for narrowing down trouble spot

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

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

AC204742BL

ECU B

ECU C

ECU D

ECU A

(a)

(b)

(c)

(d)

(e)

(f)

(g)

(h)

ETACS-ECU
(Gateway)

Data link 
connector

EXPLANATION ABOUT THE SCAN TOOL (M.U.T.-III) CAN BUS DIAGNOSTICS

TSB Revision

CONTROLLER AREA NETWORK (CAN)

54C-13

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

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

Trouble in 
CAN bus line 
(d)

If time-out diagnostic trouble 
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 
diagnostic 
trouble codes 
associated with 
ECUs A and B 
are stored in 
ECU C and ECU 
D.
Time-out 
diagnostic 
trouble codes 
associated with 
ECUs A, B, C 
and D are stored 
in ETACS-ECU.

Trouble in 
CAN bus line 
(b)

It must be assumed that a 
fault was present in CAN bus 
line (b) when the 
ETACS-ECU has set a 
time-out diagnostic trouble 
code for ECU A, B, C or D.

Time-out 
diagnostic 
trouble codes 
associated with 
ETACS-ECU is 
stored in ECU A, 
B, C and ECU D.

Diagnostic 
trouble code to 
be set

Possible 
trouble spot

Logic for narrowing down trouble spot

AC204742BM

ECU B

ECU C

ECU D

ECU A

(a)

(b)

(c)

(d)

(e)

(f)

(g)

(h)

ETACS-ECU
(Gateway)

Data link 
connector

AC204742BN

ECU B

ECU C

ECU D

ECU A

(a)

(b)

(c)

(d)

(e)

(f)

(g)

(h)

ETACS-ECU
(Gateway)

Data link 
connector

AC204742BP

ECU B

ECU C

ECU D

ECU A

(a)

(b)

(c)

(d)

(e)

(f)

(g)

(h)

ETACS-ECU
(Gateway)

Data link 
connector

DIAGNOSIS

TSB Revision

CONTROLLER AREA NETWORK (CAN)

54C-14

DIAGNOSIS

CAN BUS DIAGNOSTICS TABLE

M1548300200914

CAUTION

A diagnostic trouble code may not also be set in 
the CAN-B lines under the conditions below. If no 
diagnostic trouble code has been set due to elec-
trical noise, confirm diagnosis item 27 

P.54C-195

.

• Open circuit at the CAN_H side of the CAN-B 

bus lines

• Open circuit at the CAN_L side of the CAN-B 

bus line

• Short to ground at the CAN_H side of the 

CAN-B bus line

CAUTION

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

Scan tool screen

Diagnosis detail

Reference 
page

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

Comment

Short circuit to 
battery in red 
displayed area is 
estimated.

Diagnosis Item 1
Diagnose when the 
scan tool cannot receive 
the data sent by 
ETACS-ECU.

 

P.54C-27

AC709520AB

M.U.T.

J/C (3)

SAS

S-AWC

J/C (2)

KOS/WCM

SRS

A/C

AUDIO

MMCS

Sat Radio

HFM

OCM

METER

ASC

ENGINE

J/C (1)

ETACS

: Red section on screen

<M/T>

AC709521

ETACS

AB

M.U.T.

J/C (3)

SAS

S-AWC

J/C (2)

KOS/WCM

SRS

A/C

AUDIO

MMCS

Sat Radio

HFM

OCM

METER

ASC

LEVER

J/C (4)

ENGINE

J/C (1)

: Red section on screen

<TC-SST>

TC-SST