Diagnosis code
No.03 Communication error with front-ECU
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If diagnosis code No.03 is set
in the ETACS-ECU, diagnose the CAN bus
lines.
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The ETACS-ECU communicates with the
front-ECU through the SWS communication line. If there
is any trouble in that communication, diagnosis code No.03
will be set.
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COMMENTS ON TROUBLE SYMPTOM
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The front-ECU, the ETACS-ECU,
connector(s), or wiring harness between the two may be
defective.
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- Malfunction of the front ECU
- Malfunction of the ETACS-ECU
- Damaged harness wires and connectors
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Step 1. M.U.T.-III CAN bus diagnostics
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Use the M.U.T.-III to diagnose the
CAN bus lines.
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Q.
Is the check result normal?
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 Go to Step
2.
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 Repair the CAN bus
line (Refer to GROUP 54F - Troubleshooting  ).
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Step 2. M.U.T.-III diagnosis code
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(2)On completion, check that diagnosis code No.03 is
not reset.
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Q.
Is diagnosis code No.03 set?
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Go to Step
6.
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Go to Step
3.
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Step 3. Connector check: A-14X front-ECU
connector
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Q.
Is the check result normal?
Go to Step
4.
Repair
the defective connector.
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Step 4. Voltage measurement at the A-14X front-ECU
connector.
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(1)Remove the front-ECU, and
measure at the relay box side.
(2)Ignition switch:
ON
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(3)Voltage between A-14X front-ECU
connector terminal No.7 and body earth
OK:
System voltage
Q.
Is the check result normal?
Replace the
front-ECU.
Go to Step
5.
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Step 5. Check the wiring harness between A-14X front-ECU
connector
terminal No.7 and the fusible link (26).
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- Check the power supply line for open
circuit.
Q.
Is the check result normal?
The trouble can be
an intermittent malfunction (Refer to GROUP 00 - How
to Cope with Intermittent Malfunction ).
Repair the wiring
harness.
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Step 6. Connector check: A-15X front-ECU
connector
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Q.
Is the check result normal?
Go to Step
7.
Repair
the defective connector.
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Step 7. Resistance measurement at the A-15X front-ECU
connector.
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(1)Remove the front-ECU, and
measure at the relay box side.
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(2)Resistance between A-15X
front-ECU connector terminal No.31 and body
earth
OK: 2 Ω or less
Q.
Is the check result normal?
Go to Step
10.
Go to Step
8.
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Step 8. Connector check: A-25 earth
connector
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Q.
Is the check result normal?
Go to Step
9.
Repair
the defective connector.
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Step 9. Check the wiring harness between A-15X front-ECU
connector
terminal No.31 and A-25 earth connector terminal
No.5.
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- Check the earth wires for open circuit.
Q.
Is the check result normal?
The trouble can be
an intermittent malfunction (Refer to GROUP 00 - How
to Cope with Intermittent Malfunction ).
Repair the wiring
harness.
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Step 10. Connector check: C-221 ETACS-ECU
connector
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Q.
Is the check result normal?
Go to Step
11.
Repair
the defective connector.
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Step 11. Check the wiring harness between C-221
ETACS-ECU connector
terminal No.59 and A-15X front-ECU connector terminal
No.22.
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| note |
Prior to the wiring harness
inspection, check joint connector C-01 and
intermediate connector
C-125, and repair if necessary.
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- Check the communication lines for open
circuit.
Q.
Is the check result normal?
Go to Step
12.
Repair
the wiring harness.
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Step 12. Check whether the diagnosis code is
reset.
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Replace the front ECU, and then
check that the diagnosis code is not reset.
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(1)Replace the front ECU.
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(3)On completion, check that diagnosis code No.03 is
not reset.
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Q.
Is diagnosis code No.03 set?
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Replace the
ETACS-ECU.
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The procedure is
complete.
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