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DTC P0A09: DCDC converter fail (1)
 
 
caution
  • If there is any problem in the CAN bus lines, an incorrect DTC may be set. Prior to this diagnosis, diagnose the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnostics Table ).
  • Whenever ECU is replaced, ensure that the CAN bus lines are normal.
 
 
DTC SET CONDITIONS
The PHEV-ECU sets DTC P0A09 when the DC-DC converter remains deactivated although the PHEV-ECU attempted to activate the DC-DC converter.
 
 
 
PROBABLE CAUSES
  • Malfunction of CAN bus line.
  • Malfunction of the on board charger/DC-DC converter.
  • Damaged harness or connector.
  • Malfunction of the PHEV-ECU.
 
 
 
 
DIAGNOSIS
Required Special Tools
  • MB991223: Wiring harness set
  • MB992006: Extra fine probe
STEP 1. Using scan tool (M.U.T.-IIISE), diagnose CAN bus line.
Diagnose the CAN bus lines.
Is the check result normal?
Go to Step 2.
Repair the CAN bus lines (Refer to GROUP 54C - Troubleshooting ). On completion, go to Step 2.
 
STEP 2. Using scan tool (M.U.T.-IIISE), check whether the other DTC is set.
Check whether the on board charger/DC-DC converter related DTC is set.
Is the DTC set?
Diagnose the on board charger/DC-DC converter (Refer to ).
Go to Step 3.
 
STEP 3. Check the signal line for open circuit and short to ground (on board charger/DC-DC converter connector and the PHEV-ECU connector).
(1) Disconnect the C-41 PHEV-ECU connector, D-208 on board charger/DC-DC converter connector and measure at the wiring harness side.
(2) Measure the resistance between the terminal DCSW and body ground.
OK: No continuity
(3) Measure the resistance between on board charger/DC-DC converter connector (terminal DNSW) and the PHEV-ECU connector (terminal DCSW).
OK: Continuity exists (2 Ω or less)
Is the check result normal?
Go to Step 4.
Repair the connector or wiring harness.
 
STEP 4. Voltage measurement at PHEV-ECU (terminal DCSW).
(1) Connect the C-41 PHEV-ECU connector, D-208 on board charger/DC-DC converter connector, and measure at the wiring harness side.
(2) Measure the PHEV-ECU connector side by backprobing.
(3) Depress the brake pedal, and turn on the power supply mode of the electric motor switch (READY operation).
(4) Measure the voltage between the PHEV-ECU connector (terminal DCSW) and body ground.
OK: About 3 V lower than the system voltage.
Is the check result normal?
Go to Step 6.
Go to Step 5.
 
STEP 5. Scan tool (M.U.T.-IIISE) data list <On board charger/DC-DC converter>
Check that the following data list display contents are normal (Refer to ).
Data list
  • Item No.44: Control power supply SNS.voltage
OK: [When the brake pedal is stepped on while stepping on the brake pedal it is on (READY operation).]
Is the check result normal?
Go to Step 6.
Replace the on board charger/DC-DC converter (Refer to ).
 
STEP 6. Using scan tool (M.U.T.-IIISE), check whether the DTC is set again.
Recheck the DTC.
(1) Erase the DTC.
(2) Turn off the power supply mode of the electric motor switch.
(3) Depress the brake pedal, and turn on the power supply mode of the electric motor switch (READY operation).
(4) Check the DTC.
Is the DTC set?
Replace the PHEV-ECU (Refer to ).
The trouble can be an intermittent malfunction (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).