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 54D - Troubleshooting  ).
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STEP 2. M.U.T.-III diagnosis code
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(1)Erase the diagnosis code.
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(2)Ignition switch: LOCK (OFF) position to ON
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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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Go to Step 6.
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Go to Step 3.
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STEP 3. Connector check: A-08X front-ECU connector
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Q.
Is the check result normal?
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Go to Step 4.
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Repair
the defective connector.
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STEP 4. Voltage measurement at A-08X front-ECU connector.
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(1)Remove the front-ECU, and measure at the relay box
side.
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(2)Voltage between A-08X front-ECU connector terminal No.7
and body earth
OK: System voltage
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Q.
Is the check result normal?
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Replace the front-ECU.
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Go to Step 5.
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STEP 5. Check the wiring harness between A-08X front-ECU connector
terminal No.7 and the fusible link (1).
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- Check the power supply line for open circuit.
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Q.
Is the check result normal?
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The
trouble can be an intermittent malfunction (Refer to GROUP 00 - How
to use troubleshooting/Inspection Service Points ).
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Repair
the wiring harness.
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STEP 6. Connector check: A-09X front-ECU connector
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Q.
Is the check result normal?
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Go to Step 7.
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Repair
the defective connector.
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STEP 7. Resistance measurement at A-09X 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-09X front-ECU connector terminal
No.31 and body earth
OK: Continuity exists (2 Ω or
less)
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Q.
Is the check result normal?
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Go to Step 9.
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Go to Step 8.
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STEP 8. Check the wiring harness between A-09X front-ECU connector
terminal No.31 and the body earth.
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- Check the earth wires for open circuit.
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Q.
Is the check result normal?
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The
trouble can be an intermittent malfunction (Refer to GROUP 00 - How
to use troubleshooting/Inspection Service Points ).
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Repair
the wiring harness.
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STEP 9. Connector check: D-420 ETACS-ECU connector
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Q.
Is the check result normal?
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Go to Step 10.
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Repair
the defective connector.
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STEP 10. Check the wiring harness between D-420 ETACS-ECU connector
terminal No.59 and A-09X front-ECU connector terminal No.22.
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| note |
Prior to the wiring harness inspection, check
intermediate connector D-241, and repair if necessary.
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- Check the communication lines for open circuit.
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Q.
Is the check result normal?
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Go to Step 11.
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Repair
the wiring harness.
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STEP 11. 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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(2)Erase the diagnosis code.
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(3)Ignition switch: LOCK (OFF) position to ON
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(4)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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