Inspection Procedure 3: Communication with the Front-ECU is not
Possible.
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Whenever the ECU is replaced, ensure that the power
supply circuit, the earthing circuit and the communication circuit are
normal.
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COMMENTS ON TROUBLE SYMPTOM
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It is suspected that the power supply circuit
to the front-ECU is defective, or the wiring harness between the SWS
monitor and the front-ECU or their connector(s) is damaged. If the battery
power supply circuit to the ECU (terminal No.7 of the front-ECU) is
damaged, also check the power supply circuit from the ignition switch (IG2)
(terminal No.30 of the front-ECU), and repair if necessary.
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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. ECU check by using the SWS monitor
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Check that the power supply and earth lines to
the ETACS-ECU and the SWS communication lines are normal.
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OK: "OK" is displayed on the
"ETACS ECU" menu.
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Q.
Is the check result normal?
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 Go to Step 2.
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 Refer
to Inspection Procedure 2 "Communication with the ETACS-ECU is not possible
 ."
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STEP 2. Connector check: A-08X front-ECU connector
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Q.
Is the check result normal?
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Go to Step 3.
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Repair
the defective connector.
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STEP 3. 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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Go to Step 5.
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Go to Step 4.
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STEP 4. 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 5. Connector check: A-09X front-ECU connector
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Q.
Is the check result normal?
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Go to Step 6.
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Repair
the defective connector.
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STEP 6. 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 8.
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Go to Step 7.
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STEP 7. 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 8. Connector check: D-420 ETACS-ECU connector
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Q.
Is the check result normal?
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Go to Step 9.
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Repair
the defective connector.
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STEP 9. 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 10.
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Repair
the wiring harness.
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STEP 10. ECU check by using the SWS monitor
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Check that the power supply and earth lines to
the front-ECU and the SWS communication lines are normal.
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OK: "OK" is displayed on the
"FRONT ECU" menu.
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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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Replace the front-ECU.
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