Inspection Procedure 1: Check the hands free ECU power supply circuit. <Vehicles with radio and CD player>


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

CIRCUIT OPERATION



  • The ACC signal is received C-218 hands free ECU connector terminal No.15 from C-105 radio and CD player connector terminal No.8.
  • From the fusible link to C-127 intermediate connector, the hands free ECU uses the same power supply circuit as that of radio and CD player. Therefore, check first if the radio and CD player operates normally. If the radio and CD player does not operate normally, carry out in advance the troubleshooting of "Power of the radio and tape player does not turn ON when the ignition switch is in the "ACC" position or "ON" position". (Refer to <Vehicles without Auto Stop & Go (AS&G) System> or <Vehicles with Auto Stop & Go (AS&G) System>.)

PROBABLE CAUSES



  • The DC/DC converter may be defective. <Vehicles with Auto Stop & Go (AS&G) System>
  • Damaged harness wires and connectors
  • Malfunction of the hands free ECU
  • Malfunction of the radio and CD player
  • Damaged harness wires and connectors

DIAGNOSIS PROCEDURE

STEP 1. Check the radio and CD player operation.
Check if the radio and CD player work normally and the sound is output.

Q. Is the check result normal?
Go to Step 2
Troubleshoot the radio and CD player (Refer to ).

STEP 2. Connector check: C-218 hands free ECU connector and C-01 earth joint connector

Q. Is the check result normal?
Go to Step 3.
Repair the defective connector.

STEP 3. Resistance measurement at C-218 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 5.
Go to Step 4.

STEP 4. Check the wiring harness between C-218 hands free ECU connector terminal No.17 and C-01 earth joint connector terminal No. 1.

  • Check the body earth wires for open circuit.
note Prior to the wiring harness inspection, check the joint connector C-231, 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 5. Voltage measurement at C-218 hands free ECU connector.
(1)Disconnect C-218 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 8.
Go to Step 6.

STEP 6. Connector check: C-127 intermediate connector

Q. Is the check result normal?
Go to Step 7.
Repair the defective connector.

STEP 7. Check the wiring harness between C-218 hands free connector terminal No.1 and C-127 intermediate connector terminal No.10.

  • Check the power supply line for open circuit and short circuit.

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 8. Voltage measurement at C-218 hands free ECU connector.
(1)Disconnect C-218 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: 1V or less

Q. Is the check result normal?
Replace the hands free ECU.
Go to Step 9.

STEP 9. Connector check: C-105 radio and CD player connector

Q. Is the check result normal?
Go to Step 10.
Repair the defective connector.

STEP 10. Check the harness wire between C-105 radio and CD player connector terminal No.8 and C-218 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 the joint connector C-232 <RHD>, and repair if necessary.

Q. Is the check result normal?
Replace the radio and CD player.
Repair the wiring harness.