Inspection Procedure 2: Audio equipment is reset or sound jump occurs at auto start.


caution Even when the diagnosis code No. B1301 or B1302 is set in the AS&G-ECU, do not conclude as a DC/DC converter or AS&G-ECU error, and be sure to check the DC/DC converter power supply circuit.

COMMENTS ON TROUBLE SYMPTOM




  • Diagnosis code No. B1301 or B1302 is stored in AS&G-ECU, and voltage is not boosted by DC/DC converter at auto start
  • DC/DC converter internal malfunction
  • Battery voltage drop
  • Communication error with AS&G-ECU and DC/DC converter
  • AS&G-ECU malfunction
note If a reset or sound jump occurs with AUDIO equipment at other than the auto start, a problem is present with the power supply to the equipment that experienced the reset or sound jump. Therefore, be sure to check the power supply to the equipment.

PROBABLE CAUSES



  • The DC/DC converter may be defective.
  • The AS&G-ECU may be defective.
  • The battery may be defective.
  • Damaged harness wires and connectors

DIAGNOSIS PROCEDURE

STEP 1. Check the power supply system circuit
Check the DC/DC converter power supply circuit by referring to Troubleshooting. (Refer to .)

Q. Is the check result normal?
Go to Step 2.
Repair according to the troubleshooting, and recheck the trouble symptom.

STEP 2. Check the M.U.T.-III Diagnosis code for other systems
Check if the diagnosis code No. B1301 or B1302 is set to AS&G-ECU.

Q. Is the diagnosis code set?
Erase the diagnosis code, and then go to Step 3.
Go to Step 3.

STEP 3. Check the M.U.T.-III Diagnosis code for other systems
Check if the diagnosis code is set to AS&G-ECU.

Q. Is the diagnosis code set?
Diagnose the AS&G-ECU (Refer to GROUP 17 - Troubleshooting ).
Go to Step 4.

STEP 4. Battery test
Check the battery state.(Refer to .)

Q. Is the check result normal?
YES<Except vehicles with MMCS> : Go to Step 7.
YES<Vehicles with MMCS> : Go to Step 5.
Replace the battery

STEP 5. Connector check: C-127 intermediate connector

Q. Is the check result normal?
Go to Step 6.
Repair the defective connector.

STEP 6. Check the wiring harness between C-12 DC/DC converter connector terminal No.8 and C-127 intermediate connector terminal No.1.

  • Check the signal lines for open circuit and short circuit.

Q. Is the check result normal?
Go to Step 7.
Repair the wiring harness.

STEP 7. Replace the DC/DC converter temporarily, and check the trouble symptom.

Q. Is the check result normal?
Replace the DC/DC converter.
Replace the AS&G-ECU.