Mitsubishi Outlander GS45X. Manual - part 1266

PRECAUTIONS ON HOW TO REPAIR THE CAN BUS LINES

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CONTROLLER AREA NETWORK (CAN)

54C-9

• If the connector or wire on the main bus line or the sub-bus

wire is replaced, the frayed end of the twisted wire should
be within 10 cm (4 inches) from the connector. If it exceeds
10 cm (4 inches), twist the wiring harness just like the origi-
nal twisted wire. If the frayed end exceeds 10 cm (4 inches),
noise suppression is deteriorated, causing a communica-
tion error.

• If a sub-bus line is repaired, splice a new wire directly into

the main bus line. If a new wire is spliced into the sub-bus
line, which is connected to another device, the CAN com-
munication will be disabled.

PRECAUTIONS ON HOW TO REPAIR THE
TERMINATOR RESISTOR

If one-side terminator resistor is broken, the CAN
communication will continue although noise suppres-
sion is deteriorated. No diagnostic trouble code may
be set even if the terminator resistor was broken. If a
damage is found, replace the ECU which incorpo-
rates the defective terminator resistor.

CAN BUS LINE REPAIR HARNESS (PART
NAME AND NUMBER)

AC203824

Connector

Twisted wire

Within 10 cm
(4.0 inches)

AC202856

ECU

Good

No good

Open
circuit
point

Terminator resistor

: Shows main bus line.
: Shows sub bus line.
: Shows restored CAN bus line.

Open
circuit
point

Terminator resistor

Part name

Part number

Twist pair cable

MN151514

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

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CONTROLLER AREA NETWORK (CAN)

54C-10

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

CAN BUS DIAGNOSTICS

M1548300100586

Scan tool MB991958 CAN bus diagnostics carries
out the two checks below automatically, and then dis-
plays current condition of the CAN bus lines accord-
ing to the check results.

CAN BUS LINE DIAGNOSTIC FLOW

1. Scan tool CAN bus diagnostics

Scan tool MB991958 diagnoses CAN bus lines in
accordance with the following strategy.
NOTE: After you determine whether the CAN-C
lines are in good condition, then determine
whether the CAN-B lines are in good condition.
Then confirm each judgment result on the scan
tool screen.

(1) Check that the ETACS-ECU sets a diagnostic

trouble code.
You can narrow down the points to be
diagnosed by confirming an ETACS-ECU
diagnostic trouble code.

(2) Checking the communication condition of

ECUs
Scan tool MB991958 narrows down troubles in
circuit by itself. Its strategies are as follows.

AC507612 AE

(1) Check if a transmission error (bus off) occurred
in the ETACS-ECU.

YES

From other diagnosis

1. Scan tool MB991958
(M.U.T.-III) CAN bus
diagnostics

Go to ordinary diagnosis

OK for (2)
P code, B code,
C code or
U code (current trouble)

OK for (2)
U code (past trouble)

2. Pinpoint possible trouble
spot according to
diagnostic trouble code

Short in CAN bus line to power
supply or ground

(2) Check the communication condition of ECUs.

· Open circuit in CAN bus line
· Broken terminator resistor
· Power supply to ECU poorly grounded

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

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CONTROLLER AREA NETWORK (CAN)

54C-11

AC204741

ECU B

ECU C

ECU D

ECU A

(a)

(b)

(c)

(h)

(d)

(e)

(f)

(g)

ETACS-ECU
(Gateway)

Reference circuit

Data link
connector

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

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CONTROLLER AREA NETWORK (CAN)

54C-12

ECU which
cannot
communicate
with the scan
tool

Possible
trouble spot

Logic for narrowing down trouble spot

ETACS-ECU
and all ECUs

CAN bus line
(h) and
power supply
system to
ETACS-ECU

The ETACS-ECU and the
other ECUs use the CAN bus
line (h) when they
communicate with scan tool
MB991958. Since none of the
ETACS-ECU and the other
ECUs can communicate with
scan tool MB991958, CAN bus
line (h) or the power supply
circuit to the ETACS-ECU may
be faulty.

ECU A

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

ECU A communicates with the
scan tool MB991958 via CAN
bus lines (a) and (b). Scan tool
MB991958 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

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.

AC204742BO

ECU B

ECU C

ECU D

ECU A

(a)

(b)

(c)

(d)

(e)

(f)

(g)

(h)

ETACS-ECU
(Gateway)

Data link
connector

AC204742BH

ECU B

ECU C

ECU D

ECU A

(a)

(b)

(c)

(d)

(e)

(f)

(g)

(h)

ETACS-ECU
(Gateway)

Data link
connector

AC204742BI

ECU B

ECU C

ECU D

ECU A

(a)

(b)

(c)

(d)

(e)

(f)

(g)

(h)

ETACS-ECU
(Gateway)

Data link
connector

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