MSB is released for this page as follows:

Release Date	Subject	MSB No.
2012-01-20	EV-ECU TROUBLESHOOTING	MSB-11E54-004
2013-10-17	DTC P0A09 DCDC CONVERTER (1)	MSB-13EXML54-002
2016-03-18	DTC P0A09 DCDC CONVERTER (1)	MSB-13EXML54-002A
2018-02-15	Modification of the Troubleshooting procedure about Diagnosis Trouble Code P0A09 for EV-ECU	MSB-13EXML54-002B

Code No. P0A09: DCDC converter (1)

AUXILIARY BATTERY CHARGING CONTROL CIRCUIT

OPERATION

The driving approval and driving state control of the DC-DC converter are performed by the EV-ECU.

DIAGNOSIS CODE SET CONDITIONS

When the DC-DC converter drive stop state continues for 4 seconds or longer while the DC-DC converter driving approval is underway, the diagnosis code No. P0A09 will be set.

COMMENT ON PAST TROUBLE

When the malfunction of the system cooling system or control voltage trouble is recorded as a past trouble, the diagnosis code may be set. Check the code.

Conduct the actuator test (item 03: Water pump drive, item 04: Radiator fan 1 drive, item 05: Radiator fan 2 drive) to check the cooling system.
Visually check the radiator core.
Check the EMCU diagnosis code.
When the total battery voltage is around the low voltage limit, MCU may determine that a malfunction has occurred (not a malfunction).

PROBABLE CAUSES

Damaged wiring harness or connector(s)
Malfunction of system cooling
Malfunction of the DC-DC converter
Malfunction of the EV-ECU

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III data list

Check the BMU service data. (Refer to

Data list

Item No. 7 : Battery total voltage

OK: 210 V or more

Q. Is the check result normal?

	Go to Step 2.

	Charge the main battery. Then go to Step 10.

STEP 2. Measure the voltage at E-03 on board charger/DC-DC converter connector.

(1)Disconnect the E-03 on board charger/DC-DC converter connector, and measure the voltage at the wiring harness side.

(2)Turn the electric motor switch to the "ON" position.

(3)Measure the voltage between the E-03 on board charger/DC-DC converter connector terminal No. 8 and the body earth.
OK: Battery voltage

Q. Is the check result normal?

	Go to Step 5.

	Go to Step 3.

STEP 3. Connector check: A-08X EV control relay (relay box) connecter, B-27 intermediate connector, E-03 on board charger/DC-DC converter connector

Q. Is the check result normal?

	Go to Step 4.

	Repair the damaged connector. Or, correct or replace the relay box.

STEP 4. Check the wiring harness between A-08X EV control relay (relay box) connector terminal No. 1 and E-03 on board charger/DC-DC converter connector terminal No. 8.

Check the power supply line for open circuit.

Q. Is the check result normal?

	Go to Step 5.

	Repair the wiring harness.

STEP 5. Connector check: E-03 on board charger/DC-DC converter connecter, C-111 EV-ECU connector

Q. Is the check result normal?

	Go to Step 6.

	Repair the damaged connector.

STEP 6. Check the wiring harness between E-03 on board charger/DC-DC converter connector terminal No. 4, 11 and C-111 EV-ECU connector terminal No. 116, 127.

Check the signal lines for open circuit.

Q. Is the check result normal?

	Go to Step 7.

	Repair the wiring harness.

STEP 7. Check the wiring harness between E-03 on board charger/DC-DC converter connector terminal No. 10 and the earth.

Check the earth line for open circuit.

Q. Is the check result normal?

	Go to Step 8.

	Repair the wiring harness.

STEP 8. Check of auxiliary battery charging warning lamp

With the connector connected, apply 12 V to the C-111 EV-ECU connector terminal No. 116.

Set the electric motor switch from the "LOCK" (OFF) position to the "ON", "START" position.

OK: The auxiliary battery charging warning lamp goes out.

Q. Is the check result normal?

	Replace the on board charger/DC-DC converter. (Refer to .) Then go to Step 10.

	Go to Step 9.

STEP 9. Diagnosis code recheck

Check again if the diagnosis code is set to the EV-ECU.

(1)Erase the stored diagnosis code.

(2)Set the electric motor switch from the "LOCK" (OFF) position to the "ON" position.

(3)Check if the diagnosis code is set.

Q. Is the diagnosis code set?

	Replace the EV-ECU. (Refer to .) Then go to Step 10.

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

STEP 10. Diagnosis code recheck

Check again if the diagnosis code is set to the EV-ECU.

(1)Erase the stored diagnosis code.

(2)Set the electric motor switch from the "LOCK" (OFF) position to the "ON" position.

(3)Check if the diagnosis code is set.

Q. Is the diagnosis code set?

	Return to Step 1.

	The diagnosis is complete.

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