Code No. B1302: DC/DC Converter (Entertainment System) System


OPERATION



  • At the auto start, the AS&G-ECU connector terminal DCCT sends increasing voltage request signal to the DC/DC converter connector terminal DCCT.
  • If the increasing voltage control system is abnormal, the DC/DC converter connector terminal DCCA should send the diagnostic signal to the AS&G-ECU connector terminal DCCA.

FUNCTION



  • The AS&G-ECU checks whether the increasing voltage control system is normal.

TROUBLE JUDGMENT


Check Condition
  • Ignition switch is "ON" position.
  • The IOD fuse is installed.
Judgement Criterion
  • For 5 seconds, the high signal (OFF signal) is received in a row.

FAIL-SAFE AND BACKUP FUNCTION



  • None.

PROBABLE CAUSES



  • Failed battery
  • Open/short circuit or harness damage in DC/DC converter circuit or loose connector contact
  • Failed DC/DC converter
  • Failed AS&G-ECU

DIAGNOSIS PROCEDURE

STEP 1. Perform voltage measurement at C-65 DC/DC converter connector.
note Before checking the voltage, carry out the operation, Step 1-3, to reset the diagnosis information of the DC/DC converter. If the operation is swiftly carried out, the diagnosis code can be stored. Slowly carry out the operation, Step 1-3.

  • Disconnect connector, and measure at harness side.
  • Voltage between terminal PWR and earth.
OK: Not more than 20 V

Q. Is the check result normal?
Go to Step 2.
Replace the battery.

STEP 2. M.U.T.-III data list

  • Item 9: DC/DC converter diagnostic signal
OK: ON

Q. Is the check result normal?
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).
NO <OFF> : Go to Step 3.
NO <Failure> : Perform the troubleshooting of diagnosis code No.B1301: DC/DC converter performance malfunction (Refer to ).

STEP 3. Perform voltage measurement at DC/DC converter connector.

  • Disconnect connector, and measure at harness side.
  • Ignition switch: ON
  • Voltage between terminal DCCA and earth.
OK: System voltage

Q. Is the check result normal?
Go to Step 6.
Go to Step 4.

STEP 4. Perform voltage measurement at AS&G-ECU connector by back probing.

  • Do not disconnect connector.
  • Ignition switch: ON
  • Voltage between terminal DCCA and earth.
OK: System voltage

Q. Is the check result normal?
Repair the connector(s), or check of open circuit in DCCA line between AS&G-ECU connector and DC/DC converter connector.
Go to Step 5.

STEP 5. M.U.T.-III diagnosis code

  • Reconfirmation of the diagnosis code.

Q. Is the diagnosis code set?
Replace the AS&G-ECU.
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).

STEP 6. Check of harness damage in DCCA line between AS&G-ECU connector and DC/DC converter connector


Q. Is the check result normal?
Go to Step 7.
Repair the connector(s) or wiring harness.

STEP 7. Perform voltage measurement at DC/DC converter connector by back probing.

  • Do not disconnect connector.
  • Ignition switch: ON
  • Voltage between terminal DCCA and earth.
OK: 1 V or less

Q. Is the check result normal?
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).
Replace the DC/DC converter.