Code No. B1352: DC/DC Converter (Control System) System


OPERATION



  • At the auto start, the AS&G-ECU connector terminal DCCP sends increasing voltage request signal to the DC/DC converter (control system) connector terminal DCCP.
  • If the increasing voltage control system is abnormal, the DC/DC converter (control system) connector terminal DCDP sends a diagnostic signal to the AS&G-ECU connector terminal DCDP.

FUNCTION



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

TROUBLE JUDGMENT


Check Condition
  • Ignition switch is "ON" position.
  • Battery voltage is 6.3 V or more.
  • Not in auto stop.
Judgement Criterion
  • For 2 seconds, the High signal (OFF signal) is received in a row.

FAIL-SAFE AND BACKUP FUNCTION



  • In the normal operation, the auto stop is prohibited.
  • If the malfunction is detected during the auto stop, the auto start is prohibited.

PROBABLE CAUSES



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

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III diagnosis code

Q. Is diagnosis code No. B1353 set?
Perform the troubleshooting of diagnosis code No. B1353: DC/DC converter (control system) control circuit .
Go to Step 2.

STEP 2. Perform voltage measurement at DC/DC converter (control system) connector.
note Before checking the voltage, carry out the operation, Step 1-3, to reset the diagnosis information of the DC/DC converter (control system). 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 "ON" position.
  2. Turn the ignition switch to "LOCK" (OFF) position.
  3. Repeat Steps 1-2.

  • 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 3.
Replace the battery.

STEP 3. M.U.T.-III data list

  • Item 27: DC-DC OUT for powertrain (Input)
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. B1351: DC/DC converter (control system) system malfunction (Refer to ).

STEP 4. Check the DC/DC converter (control system) power supply circuit.

  • Disconnect connector, and measure at harness side.
  • Ignition switch: ON
  • Voltage between terminal DCDP 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 AS&G-ECU connector.

  • Measure the voltage AS&G-ECU connector terminal.
  • Ignition switch: ON
  • Voltage between terminal DCDP and earth.
OK: System voltage

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

STEP 6. Perform voltage measurement at AS&G-ECU connector.

Q. Is the check result normal?

    Repair the connector(s), or check and repair of short to earth in DCDP line between AS&G-ECU connector and DC/DC converter (control system) connector.
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. Check of harness damage in DCDP line between AS&G-ECU connector and DC/DC converter (control system) connector


Q. Is the check result normal?
Go to Step 9.
Repair the connector(s) or wiring harness.

STEP 9. Perform voltage measurement at DC/DC converter (control system) connector by back probing.

  • Measure the voltage DC/DC converter (control system) connector terminal.
  • Ignition switch: ON
  • Voltage between terminal DCDP 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 (control system).