Mitsubishi 380. Manual — part 739
DIAGNOSIS
CONTROLLER AREA NETWORK (CAN)
54C-367
DIAGNOSTIC ITEM 9: Diagnose the lines between CAN main bus line and the ENGINE-ECU
NOTE: When diagnosing CAN-BUS on vehi-
cles with manual transmission (M/T), disregard
A/T-ECU and it’s wiring circuits and measure
between ABS-ECU and ENGINE-ECU only.
NOTE: When diagnosing CAN-BUS on vehicles
not equipped with a multi-centre display, disre-
gard the multi-centre display and it’s wiring cir-
cuits.
CAUTION
When servicing a CAN bus line, ground yourself
by touching a metal object such as an unpainted
water pipe. If you fail to do so, a component con-
nected to the CAN bus line may be damaged.
.
TROUBLE JUDGMENT
If the MUT-III cannot receive signals from the
ENGINE-ECU, CAN bus line connector(s) are bro-
ken or an open circuit has occurred.
.
COMMENTS ON TROUBLE SYMPTOM
The wiring harness wire or connectors may have
loose, corroded, or damage terminals, or terminals
pushed back in the connector, or the ENGINE-ECU
may be defective.
.
TROUBLESHOOTING HINTS
• Refer to circuit diagrams GROUP-
• Refer to configuration diagrams GROUP-
• The wiring harness or connectors may have
loose, corroded, or damage terminals, or termi-
nals pushed back in the connector
• The ENGINE-ECU may be defective
• The A/T-ECU may be defective
NOTE: When diagnosing CAN-BUS on vehi-
cles with manual transmission (M/T), disregard
A/T-ECU and it’s wiring circuits and measure
between ABS-ECU and ENGINE-ECU only.
16DB400A
COVER
ENGINE
CONTROL
UNIT
AIR
CLEANER
16DB480A
COVER
ENGINE
CONTROL
UNIT
AIR
CLEANER
A/T
CONTROL
UNIT
DIAGNOSIS
CONTROLLER AREA NETWORK (CAN)
54C-368
DIAGNOSIS
Required Special Tools:
• MB991223: Harness Set
• MB991219: Inspection Test Harness
• MB992044: ENGINE-ECU Harness
• MB992045: A/T-ECU Harness
STEP 1. Check A/T-ECU connector B-19 and ENGINE-ECU
connector B-21 for loose, corroded or damaged terminals,
or terminals pushed back in the connector.
NOTE: when diagnosing CAN-BUS on vehicles with
manual transmission (M/T), disregard A/T-ECU and it’s wir-
ing circuits and check between ABS-ECU and
ENGINE-ECU only.
CAUTION
The strand end of the twisted wire should be within 10 cm
(4 inches) from the connector. For details refer to
Q: Are A/T-ECU connector B-19 and ENGINE-ECU
connector B-21 in good condition?
YES : Go to Step 2.
NO : Repair the damaged parts.
16DB400A
COVER
ENGINE
CONTROL
UNIT
AIR
CLEANER
16DB480A
COVER
ENGINE
CONTROL
UNIT
AIR
CLEANER
A/T
CONTROL
UNIT
DIAGNOSIS
CONTROLLER AREA NETWORK (CAN)
54C-369
STEP 2. Check the CAN bus lines between the
ENGINE-ECU and the A/T-ECU. Measure the resistance
between ENGINE-ECU connector B-21 and A/T-ECU
connector B-19.
NOTE: when diagnosing CAN-BUS on vehicles with
manual transmission (M/T), disregard A/T-ECU and it’s wir-
ing circuits and check between ABS-ECU and
ENGINE-ECU only.
CAUTION
A digital multimeter should be used. For details refer to
CAUTION
The test wiring harness should be used. For details refer to
(1) Disconnect ENGINE-ECU connector B-21 and A/T-ECU
connector B-19, and measure the resistance between each
wiring harness side connector.
(2) Turn the ignition switch to the "LOCK" (OFF) position.
CAUTION
Disconnect the negative battery terminal. For details refer
to
.
(3) Disconnect the negative battery terminal.
16DB400A
COVER
ENGINE
CONTROL
UNIT
AIR
CLEANER
16DB480A
COVER
ENGINE
CONTROL
UNIT
AIR
CLEANER
A/T
CONTROL
UNIT
DIAGNOSIS
CONTROLLER AREA NETWORK (CAN)
54C-370
(4) Measure the resistance between ENGINE-ECU connector
B-21 terminal 86 and A/T-ECU connector B-19 terminal 5.
OK: 2 ohms or less
(5) Measure the resistance between ENGINE-ECU connector
B-21 terminal 64 and A/T-ECU connector B-19 terminal 4.
OK: 2 ohms or less
NOTE: when diagnosing CAN-BUS on vehicles with
manual transmission (M/T), disregard A/T-ECU and it’s wir-
ing circuits and check between ABS-ECU and
ENGINE-ECU only.
CAUTION
Strictly observe the specified wiring harness repair proce-
dure. For details refer to
Q: Do all the resistances measure 2 ohms or less?
YES : If all the resistances measure 2 ohms or less, go to
Step 3.
NO : If either of the resistances measures more than 2
ohms or all the resistances measure more than 2
ohms, repair the wiring harness between
ENGINE-ECU connector B-21 and the A/T-ECU
connector B-19.
16DB510A
HARNESS SIDE: B-19
TEST
HARNESS
TEST
HARNESS
HARNESS SIDE: B-21
16DB511A
HARNESS SIDE: B-19
TEST
HARNESS
TEST
HARNESS
HARNESS SIDE: B-21
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