Inspection Procedure 1: Power is not turned ON when the power switch is turned ON.


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










OPERATION


When the ignition switch is in the ON or ACC position, the audio unit power can be turned ON. With the audio unit power ON, when the ignition switch is turned to the OFF position, the power for audio unit is also turned OFF.

COMMENTS ON TROUBLE SYMPTOM


Provided that the audio diagnosis code is not set, if the power for audio unit cannot be turned ON, the audio unit, or power supply circuit for audio unit may have a problem, or the option coding information may be inconsistent.

PROBABLE CAUSES



DIAGNOSIS PROCEDURE

STEP 1. ETACS-ECU coding data check
(1)Operate the M.U.T.-III to read the ETACS-ECU option coding information (Refer to GROUP 00 - Coding Table ).
(2)Check that the "AUDIO" is set to "enabled."

Q. Is the check result normal?
Go to Step 2.
Operate the M.U.T.-III to set the option coding "AUDIO" to "enabled," and check the trouble symptom.

STEP 2. M.U.T.-III other system diagnosis code
Check if the diagnosis code is set to the ETACS-ECU.

Q. Is the check result normal?
Troubleshoot the ETACS-ECU. Refer to ETACS-ECU - Troubleshooting .
Go to Step 3.

STEP 3. Connector check: C-317 ETACS-ECU connector, C-18 audio unit connector

Q. Is the check result normal?
Go to Step 4.
Repair the defective connector.

STEP 4. Check the wiring harness between C-317 ETACS-ECU connector terminal No.1 and C-18 audio unit connector terminal No.30

  • Check the power supply lines (battery power supply) for open circuit.

Q. Is the check result normal?
Go to Step 5.
Repair the wiring harness.

STEP 5. M.U.T.-III other system data list
Check the input signal of ACC relay.

  • Turn the ignition switch to the ACC position.
Item No.
 Item name
 Normal condition
Item 288
 ACC switch
 ON
OK: Normal condition is displayed.

Q. Is the check result normal?
Go to Step 6.
Refer to ETACS - Inspection Procedure 1 "The ignition switch (ACC) signal is not received" .

STEP 6. Voltage measurement at C-307 ETACS-ECU connector.
(1)Disconnect the connector, and measure at the wiring harness-side connector.
(2)Turn the ignition switch to the ACC position.
(3)Voltage between C-307 ETACS-ECU connector terminal No.2 and the body earth
OK: Battery voltage

Q. Is the check result normal?
Go to Step 8.
Go to Step 7.

STEP 7. Check the wiring harness between C-307 ETACS-ECU connector terminal No.2 and the fusible link No.34

  • 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. Connector check: C-315 ETACS-ECU connector

Q. Is the check result normal?
Go to Step 9.
Repair the defective connector.

STEP 9. Voltage measurement at C-315 ETACS-ECU connector.
(1)Disconnect the connector, and measure at the ETACS-ECU side connector.
(2)Turn the ignition switch to the ACC position.
(3)Voltage between C-315 ETACS-ECU connector terminal No.9 and the body earth
OK: Battery voltage

Q. Is the check result normal?
Go to Step 10.
Replace the ETACS-ECU.

STEP 10. Check the wiring harness between C-18 audio unit connector terminal No.21 and C-315 ETACS-ECU connector No.9

  • Check the power supply line for open circuit.

Q. Is the check result normal?

    Go to Step 11.
Repair the wiring harness.

STEP 11. Resistance measurement at C-18 audio unit connector.
(1)Disconnect the connector, and measure at the wiring harness side.
(2)Measure the resistance between C-104 audio unit connector terminal No.40 and the body earth.
OK: Continuity exists (2 Ω or less)

Q. Is the check result normal?
Go to Step 13.
Go to Step 12.

STEP 12. Check the wiring harness between C-18 audio unit connector terminal No.40 and the body earth

  • Check the earth wires for open 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 13. Retest the system
Check if the audio unit power is turned ON.

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 ).
Replace the audio unit.