Mitsubishi Motors Service Manual

2018 / ECLIPSE CROSS / EC - Workshop Manual

13 -FUEL > 13A-DIRECT INJECTION AND MULTIPOINT FUEL INJECTION (DI AND MPI) > TROUBLESHOOTING > DIAGNOSIS CODE PROCEDURES > CODE NO. B1351: DC/DC CONVERTER (CONTROL SYSTEM) PERFORMANCE<CVT><CVT>

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

OPERATION

At the auto start, the engine-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 engine-ECU connector terminal DCDP.

FUNCTION

The engine-ECU checks whether the increasing voltage control system is normal.

TROUBLE JUDGEMENT

Check Conditions

2 seconds later after the ignition switch has been in ON position.
Battery voltage is 6.3 V or more.
Not in auto stop.

Judgement Criterion

For 12 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.

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 engine-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.

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.-IIISE 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 set. Slowly carry out the operation, Step 1-3.

Turn the ignition switch to "ON" 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 191: DC-DC OUT for powertrain (Input)

OK: ON

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 DC/DC converter (control system) power supply circuit.

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

Is the check result normal?

Go to Step 4.

Repair the connector(s) or wiring harness. Then go to Step 4.

STEP 4. Perform voltage measurement at engine-ECU connector.

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

OK: System voltage

Is the check result normal?

Go to Step 6.

Go to Step 5.

STEP 5. Check of short to earth, and open circuit in DCCP line between DC/DC converter (entertainment system) connector and engine-ECU connector.

Is the check result normal?

Replace the DC/DC converter (control system).

Repair the connector(s) or wiring harness.

STEP 6. Perform voltage measurement at DC/DC converter (control system) connector by back probing.

Measure DC/DC converter (control system) terminal voltage.
Ignition switch: ON
Voltage between terminal DCCP and body earth.

OK: 1 V or less

Is the check result normal?

Go to Step 8.

Go to Step 7.

STEP 7. M.U.T.-IIISE diagnosis code

Reconfirmation of the diagnosis code.

Is the diagnosis code set?

Replace the engine-ECU.

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

STEP 8. Perform voltage measurement at DC/DC converter (control system) connector.

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

OK: System voltage

Is the check result normal?

Go to Step 9.

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

STEP 9. Check of damage in DCCP line between engine-ECU connector and DC/DC converter (control system) connector

Is the check result normal?

Go to Step 10.

Repair the connector(s) or wiring harness.

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

Measure DC/DC converter (control system) terminal voltage.
Voltage between terminal OUT1 and body earth at auto start.
Voltage between terminal OUT2 and body 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

Is the check result normal?

Go to Step 11.

Replace the DC/DC converter (control system).

STEP 11. M.U.T.-IIISE diagnosis code

note	Before rechecking whether 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 set. Slowly carry out the operation, Step 1-3.

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

Is the diagnosis code set?

Replace the DC/DC converter (control system). Then go to Step 12.

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

STEP 12. M.U.T.-IIISE diagnosis code

Reconfirmation of the diagnosis code.

Is the diagnosis code set?

Replace the engine-ECU.

Check end.