Code No. B1302: DC/DC Converter System Malfunction


OPERATION



  • At the auto start, the AS&G-ECU (terminal No. 11) sends increasing voltage request signal to the DC/DC converter (terminal No. 5).
  • If the increasing voltage control system is abnormal, the DC/DC converter (terminal No. 4) should send the diagnostic signal to the AS&G-ECU (terminal No. 17).

FUNCTION



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

TROUBLE JUDGMENT


Check Condition
  • Ignition switch is "ON" position.
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. Connector check: C-12 DC/DC converter connector
note Before checking the connector, 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.

  1. Turn the ignition switch to "ACC" position.
  2. Turn the ignition switch to "LOCK" (OFF) position.
  3. Repeat Steps 1-2.

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

STEP 2. Perform voltage measurement at C-12 DC/DC converter connector.

  • Disconnect connector, and measure at harness side.
  • Voltage between terminal No. 9 and earth.
OK: Not more than 20 V

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

STEP 3. 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 4.
NO <Failure> : Perform the troubleshooting of diagnosis code No. B1301: DC/DC converter performance malfunction (Refer to ).

STEP 4. Perform voltage measurement at C-12 DC/DC converter connector.

  • Disconnect connector, and measure at harness side.
  • Ignition switch: ON
  • Voltage between terminal No. 4 and earth.
OK: System voltage

Q. Is the check result normal?
Go to Step 8.
Go to Step 5.

STEP 5. Perform voltage measurement at C-11 AS&G-ECU connector by back probing.

  • Do not disconnect connector.
  • Ignition switch: ON
  • Voltage between terminal No. 17 and earth.
OK: System voltage

Q. Is the check result normal?
Go to Step 6.
Go to Step 7.

STEP 6. Connector check: C-11 AS&G-ECU connector

Q. Is the check result normal?

    Check and repair harness between C-11 (terminal No. 17) AS&G-ECU connector and C-12 (terminal No. 4) DC/DC converter connector.

    • Check signal line for open circuit.
Repair or replace the connector.

STEP 7. 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 8. Connector check: C-11 AS&G-ECU connector

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

STEP 9. Check harness between C-11 (terminal No. 17) AS&G-ECU connector and C-12 (terminal No. 4) DC/DC converter connector



  • Check signal line for damage.

Q. Is the check result normal?
Go to Step 10.
Repair the damaged harness wire.

STEP 10. Perform voltage measurement at C-12 DC/DC converter connector by back probing.

  • Do not disconnect connector.
  • Ignition switch: ON
  • Voltage between terminal No. 4 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.