INSPECTION
PROCEDURE 14: A/C-ECU power supply system
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COMMENTS ON TROUBLE SYMPTOM
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If the A/C-ECU is not energised, the power supply or earth system to the ECU
may be defective.
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- Malfunction of A/C-ECU
- Wiring harness or connector failure
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STEP 1. M.U.T.-III other system’s diagnosis code
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Check that the ETACS-ECU has not set a diagnosis code.
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Q.
Is the diagnosis code set?
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 Carry out the diagnosis code procedures . Refer to GROUP 54A, ETACS-ECU  .
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 Go to Step 2.
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STEP 2. Connector check: C-111 A/C-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 connector concerned.
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STEP 3. Measure the voltage at the C-111 A/C-ECU connector.
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(1)Disconnect the connector, and measure at the wiring harness side.
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(3)Voltage between terminal No. 15 and body earth
OK: Battery voltage
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Q.
Is the check result normal?
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Go to Step 6.
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Go to Step 4.
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STEP 4. Connector check: C-317 ETACS-ECU connector
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Q.
Is the check result normal?
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Go to Step 5.
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Repair the connector concerned.
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STEP 5. Check the wiring harness between C-111 A/C-ECU connector
terminal No. 15 and C-317 ETACS-ECU connector terminal No. 5.
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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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Intermittent malfunction (Refer to GROUP 00 -
How to Use Troubleshooting/Inspection
Service Points - How to Cope with Intermittent Malfunction ).
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Repair the wiring harness.
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STEP 6. Measure the voltage at the C-111 A/C-ECU connector.
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(1)Disconnect the connector, and measure at the wiring harness side.
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(2)Voltage between terminal No. 13 and body earth
OK: Battery voltage
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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 C-111 A/C-ECU connector
terminal No. 13 and C-317 ETACS-ECU connector terminal No. 10.
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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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Intermittent malfunction (Refer to GROUP 00 -
How to Use Troubleshooting/Inspection
Service Points - How to Cope with Intermittent Malfunction ).
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Repair the wiring harness.
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STEP 8. Measure the resistance at the C-111 A/C-ECU connector.
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(1)Disconnect the connector, and measure at the wiring harness side.
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(2)Resistance between terminal No. 14 and body earth
OK: Continuity exists (2 Ω
or less)
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Q.
Is the check result normal?
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Replace the A/C-ECU.
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Go to Step 9.
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STEP 9. Check the wiring harness between C-111 A/C-ECU connector
terminal No. 14 and 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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Intermittent malfunction (Refer to GROUP 00 -
How to Use Troubleshooting/Inspection
Service Points - How to Cope with Intermittent Malfunction ).
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Repair the wiring harness.
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