Code No. B1301: DC/DC Converter (Entertainment System) Performance

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 duty signal (failure signal) is received in a row.

FAIL-SAFE AND BACKUP FUNCTION

None.

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 circuit or loose connector contact
Failed DC/DC converter
Failed AS&G-ECU

DIAGNOSIS PROCEDURE

STEP 1. 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 2.

	Go to Step 2.

STEP 2. 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. If the operation is swiftly carried out, the diagnosis code can be stored. Slowly carry out the operation, Step 1-3.

Turn the ignition switch to "ACC" position.
Turn the ignition switch to "LOCK" (OFF) position.
Repeat Steps 1-2.
Turn the ignition switch to "ON" position and check the data list after having passed for more than 60 seconds.

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 ).

	Go to Step 3.

STEP 3. Check the operation of the accessories

Ignition switch: ACC

OK: Radio and CD player operates or multivision display operates

Q. Is the check result normal?

	Go to Step 4.

	NO <Vehicles with radio and CD player> : Perform the troubleshooting of the radio and CD player (Refer to GROUP 54A - Radio and CD Player - Symptom Chart ).

	NO <Vehicles with MMCS> : Perform the troubleshooting of the multivision display (Refer to GROUP 54A - Mitsubishi Multi Communication System (MMCS) - Symptom Chart ).

STEP 4. Check the DC/DC converter power supply circuit

Check the DC/DC converter power supply circuit (Refer to GROUP 54A - DC/DC Converter - Symptom Procedures - Check the DC/DC Converter Power Supply Circuit ).

Q. Is the check result normal?

	Go to Step 5.

	Repair the circuit according to the troubleshooting and go to Step 5.

STEP 5. Perform voltage measurement at AS&G-ECU connector.

Disconnect connector, and measure at harness side.
Ignition switch: ON
Voltage between terminal DCCT and earth.

OK: System voltage

Q. Is the check result normal?

	Go to Step 7.

	Go to Step 6.

STEP 6. Check of short to power supply, short to earth, and open circuit in DCCA line between AS&G-ECU connector and DC/DC converter connector

Q. Is the check result normal?

	Replace the DC/DC converter.

	Repair the connector(s) or wiring harness.

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

Do not disconnect connector.
Ignition switch: ON
Voltage between terminal DCCT and earth.

OK: 1 V or less

Q. Is the check result normal?

	Go to Step 9.

	Go to Step 8.

STEP 8. 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 9. 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 10.

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

STEP 10. Check of harness damage in DCCT line between AS&G-ECU connector and DC/DC converter connector

Q. Is the check result normal?

	Go to Step 11.

	Repair the connector(s) or wiring harness.

STEP 11. Perform voltage measurement at DC/DC converter connector by back probing.

Do not disconnect connector.
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 12.

	Replace the DC/DC converter.

STEP 12. 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. If the operation is swiftly carried out, the diagnosis code can be stored. Slowly carry out the operation, Step 1-3.

Turn the ignition switch to "ACC" position.
Turn the ignition switch to "LOCK" (OFF) position.
Repeat Steps 1-2.
Confirm again whether the diagnosis code is set.

Q. Is the diagnosis code set?

	Replace the DC/DC converter. Then go to Step 13.

	Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).

STEP 13. M.U.T.-III diagnosis code

Reconfirmation of the diagnosis code.

Q. Is the diagnosis code set?

	Replace the AS&G-ECU.

	Check end.