Code No. B1351: DC/DC Converter (Control System) Performance




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 duty signal (failure 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



  • Connection with accessories having rated output current large enough to possibly cause overloads (overcurrents).
  • Modified circuit
  • 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. Check the vehicle status for use



  • Ask the user whether he or she connects the vehicle with accessories having the rated output current large enough to possibly cause overloads (overcurrents) or not. Or ask the user whether he or she modifies the circuit or not.

Q. Does the user connect the vehicle with accessories having the large rated output current? Or does the user modify the circuit?

Turn OFF the accessories or remove them. Then go to Step 3.
Go to Step 3.

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


note Before checking the data list, 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.
  4. Turn the ignition switch to "ON" position and check the data list after having passed for more than 60 seconds.

  • 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).
Go to Step 4.

STEP 4. M.U.T.-III diagnosis code


Q. Is the diagnosis code U0101 set?

Perform the troubleshooting of diagnosis code No. U0101: CVT CAN timeout .
Go to Step 5.

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


Q. Is the diagnosis code U0101 set?

Perform the troubleshooting of diagnosis code No. U0121: ASC-ECU CAN timeout .
Go to Step 6.

STEP 6. Check the DC/DC converter (control system) power supply circuit.


Check the DC/DC converter (control system) power supply circuit (Refer to GROUP 23A - Troubleshooting - Inspection procedure 8: DC/DC converter power supply system check ).

Q. Is the check result normal?

Go to Step 7.
Revise a circuit according to troubleshooting. Then go to Step 7.

STEP 7. Perform voltage measurement at AS&G-ECU connector.



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

Q. Is the check result normal?

Go to Step 9.
Go to Step 8.

STEP 8. Check of short to earth and open circuit in DCCP line between DC/DC converter (entertainment system) connector and AS&G-ECU connector.



  • Check output line for open/short circuit.

Q. Is the check result normal?

Replace the DC/DC converter (control system).
Repair the connector(s) or wiring harness.

STEP 9. Perform voltage measurement at AS&G-ECU connector.



  • Measure the voltage AS&G-ECU connector terminal.
  • Ignition switch: ON
  • Voltage between terminal DCCP and earth.
OK: 1 V or less

Q. Is the check result normal?

Go to Step 11.
Go to Step 10.

STEP 10. 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 11. Perform voltage measurement at DC/DC converter (control system) connector by back probing.



  • 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 12.

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

STEP 12. Check of harness damage in DCCP line between AS&G-ECU connector and DC/DC converter (control system) connector


Q. Is the check result normal?

Go to Step 13.
Repair the connector(s) or wiring harness.

STEP 13. Perform voltage measurement at DC/DC converter (control system) connector by back probing.



  • Measure the voltage DC/DC converter (control system) connector terminal.
  • Measure the voltage between terminal OUT1 and earth at auto start.
  • Measure the voltage between terminal OUT2 and earth at auto start.
  • Check the difference among the measured voltage of the terminal OUT1 and the measured voltage of the terminal OUT2.
OK: Under 0.3 V

Q. Is the check result normal?

Go to Step 14.
Replace the DC/DC converter (control system).

STEP 14. M.U.T.-III diagnosis code


note Before rechecking the diagnosis code is set, 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.
  4. Confirm again whether the diagnosis code is set.

Q. Is the diagnosis code set?

Replace the DC/DC converter (control system). Then go to Step 15.
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions).

STEP 15. M.U.T.-III diagnosis code



  • Reconfirmation of the diagnosis code.

Q. Is the diagnosis code set?

Replace the AS&G-ECU.
Check end.