Inspection Procedure 1: Check the hands free-ECU power supply circuit.


caution Before replacing the ECU, ensure that the power supply circuit, the earth circuit and the communication circuit are normal.










CIRCUIT OPERATION



  • The power supply to the hands free-ECU is provided by the fusible link (1).
  • The ACC signal is received from D-211 radio and CD player or CD changer connector terminal No.17. <vehicles with radio and CD player>
  • The ACC signal is received from D-204 multivision display connector terminal No.102. <vehicles with MMCS>

PROBABLE CAUSES



  • Damaged harness wires and connectors
  • Malfunction of the hands free ECU
  • Malfunction of the radio and CD player or CD changer <vehicles with radio and CD player or CD changer>
  • Malfunction of the multivision display <vehicles with MMCS>

DIAGNOSIS PROCEDURE

STEP 1. Connector check: D-143 hands free-ECU connector

Q. Is the check result normal?
Go to Step 2.
Repair the defective connector.

STEP 2. Resistance measurement at D-143 hands free-ECU connector.
(1)Disconnect the connector, and measure at the wiring harness side.
(2)Check the continuity between terminal 17 and earth.
OK: Continuity exists (2 Ω or less)

Q. Is the check result normal?
Go to Step 4.
Go to Step 3.

STEP 3. Check the wiring harness between D-143 hands free-ECU connector terminal No.17 and body earth.

  • Check the body earth wires for open circuit.
note Prior to the wiring harness inspection, check D-141 intermediate connector, and repair if necessary.

Q. Is the check result normal?
The trouble can be an intermittent malfunction (Refer to GROUP 00, How to use Troubleshooting/inspection Service Points - How to Cope with Intermittent Malfunction ).
Repair the wiring harness.

STEP 4. Voltage measurement at D-143 hands free-ECU connector.
(1)Disconnect D-143 hands free-ECU connector, and measure at the wiring harness side.
(2)Measure the voltage between terminal No.1 and body earth.
OK: System voltage

Q. Is the check result normal?
Go to Step 6.
Go to Step 5.

STEP 5. Check the wiring harness between D-143 hands free-ECU connector terminal No.1 and fusible link (1).

  • Check the power supply line for open circuit and short circuit.
note Prior to the wiring harness inspection, check D-241, D-141 intermediate connectors, and repair if necessary.

Q. Is the check result normal?
The trouble can be an intermittent malfunction (Refer to GROUP 00, How to use Troubleshooting/inspection Service Points - How to Cope with Intermittent Malfunction ).
Repair the wiring harness.

STEP 6. Voltage measurement at D-143 hands free-ECU connector.
(1)Disconnect D-143 hands free-ECU connector, and measure at the wiring harness side.
(2)Turn the ignition switch to "ACC" position.
(3)Measure the voltage between terminal No.15 and body earth.
OK: 1 voltage or less

Q. Is the check result normal?
Replace the hands free-ECU.
Go to Step 7.

STEP 7. Connector check: D-211 radio and CD player or CD changer connector <vehicles with radio and CD player or CD changer> or D-204 multivision display connector <vehicles with MMCS>

Q. Is the check result normal?
Go to Step 8.
Repair the defective connector.

STEP 8. Check the harness wire between D-211 radio and CD player or CD changer connector terminal No.17 <vehicles with radio and CD player or CD changer> or D-204 multivision display connector terminal No.102 <vehicles with MMCS> and D-143 hands free-ECU connector terminal No.15.

  • Check the signal line for open circuit and short circuit.
note Prior to the wiring harness inspection, check intermediate connector D-141, and repair if necessary.

Q. Is the check result normal?
Replace the radio and CD player or CD changer <vehicles with radio and CD player or CD changer> or multivision display <vehicles with MMCS>.
Repair the wiring harness.