Code No. B1356: DC/DC Converter (Control System) Diag Output Line

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 the DC/DC converter’s (control system) diagnostic signal circuit whether it is normal.

TROUBLE JUDGMENT

Check Condition

For 10 seconds after the ignition is switched "OFF".

Judgement Criterion

The Low signal (ON signal) is received in a row.

FAIL-SAFE AND BACKUP FUNCTION

In the normal operation, the auto stop is prohibited.

PROBABLE CAUSES

Short circuit 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. 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 earth.

OK: System voltage

Q. Is the check result normal?

	Go to Step 2.

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

STEP 2. M.U.T.-III data list

Ignition switch: ON
Disconnect DC/DC converter (control system) connector.
Item 27: DC-DC OUT for powertrain (Input)

OK: OFF

Q. Is the check result normal?

	Go to Step 4.

	Go to Step 3.

STEP 3. 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 4. M.U.T.-III diagnosis code

Reconfirmation of the diagnosis code.

Q. Is the diagnosis code set?

	Replace the DC/DC converter (control system).

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