Inspection Procedure 1: Check the hands free-ECU power supply circuit.
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Before replacing the ECU, ensure that the power supply circuit, the earth circuit and the communication circuit are normal.
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- The hands free-ECU is energised via the fusible link.
- The ACC signal is received through the radio and CD player.
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- Malfunction of the hands free-ECU
- Malfunction of the radio and CD player
- Damaged harness wires and connectors
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STEP 1. Resistance measurement at hands free-ECU connector (GND terminal).
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(1)Disconnect hands free-ECU connector, and measure at the wiring harness side.
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(2)Check the continuity between GND terminal and 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 3.
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 Go to Step 2.
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STEP 2. Check of open circuit in GND line between hands free-ECU connector and body earth.
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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 - How to Cope with Intermittent Malfunction  ).
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Repair the connector(s) or wiring harness.
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STEP 3. Voltage measurement at hands free-ECU connector (+B terminal).
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(1)Disconnect hands free-ECU connector, and measure at the wiring harness side.
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(2)Measure the voltage between +B terminal 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 of short to power supply, short to earth, and open circuit in +B line between fusible link and hands free-ECU connector.
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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 - How to Cope with Intermittent Malfunction ).
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Repair the connector(s) or wiring harness.
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STEP 5. Voltage measurement at hands free-ECU connector (P-ON terminal).
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(1)Disconnect hands free-ECU connector, and measure at the wiring harness side.
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(2)Turn the ignition switch to "ACC" position.
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(3)Measure the voltage between P-ON terminal and body earth.
OK: System voltage
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Q.
Is the check result normal?
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Replace the hands free-ECU.
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Go to Step 6.
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STEP 6. Check of short to power supply, short to earth, and open circuit in P-ON line between hands free-ECU connector and radio and CD player connector.
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Q.
Is the check result normal?
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Replace the radio and CD player.
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Repair the connector(s) or wiring harness.
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