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DTC P0AA4: Main contactor N weld
danger
  • When servicing the high voltage system parts, always shut off the high voltage by removing the service plug (Refer to ).
  • When servicing the high voltage system parts, always wear the protective equipment or armor to measure the high voltage (Refer to ).
cautionBefore replacing the ECU, ensure that the communication circuit is normal.
 
 
 
 
DESCRIPTIONS OF MONITOR METHODS
  • The inverter voltage of the front electric motor control unit (FEMCU) or rear electric motor control unit (REMCU) is monitored to judge ON/OFF status of each contactor.
  • The stuck on failure of each contactor is judged under the following conditions.
    • Main contactor (N) stuck ON: Main contactor (P) control circuit active command off.
    • Main contactor (N) stuck ON: Main contactor (N) control circuit active command off.
    • Main contactor (N) stuck ON: Charging contactor control circuit active command on.
 
 
MONITOR EXECUTION
  • Continuous
 
 
MONITOR EXECUTION CONDITIONS (Other monitor and Sensor)
Other Monitor (There is no temporary DTC stored in memory for the item monitored below)
  • EV-CAN monitor
  • Front electric motor control unit (FEMCU) current monitor
  • Front electric motor control unit (FEMCU) coil temperature monitor
  • Front electric motor control unit (FEMCU) IGBT temperature monitor
  • Front electric motor control unit (FEMCU) capacitor temperature monitor
  • Front electric motor control unit (FEMCU) control module temperature monitor
  • Front electric motor control unit (FEMCU) 3 phase circuit monitor
  • Rear electric motor control unit (REMCU) current monitor
  • Rear electric motor control unit (REMCU) coil temperature monitor
  • Rear electric motor control unit (REMCU) IGBT temperature monitor
  • Rear electric motor control unit (REMCU) capacitor temperature monitor
  • Rear electric motor control unit (REMCU) control module temperature monitor
  • Rear electric motor control unit (REMCU) 3 phase circuit monitor
  • Front electric motor control unit (FEMCU) inverter voltage monitor
  • Rear electric motor control unit (REMCU) inverter voltage monitor
  • Front electric motor control unit (FEMCU) Control module circuit monitor
  • Rear electric motor control unit (REMCU) control module circuit monitor
Sensor (The sensor below is determined to be normal)
  • Front electric motor control unit (FEMCU) current sensor
  • Front electric motor control unit (FEMCU) coil temperature sensor
  • Front electric motor control unit (FEMCU) position sensor
  • Front electric motor control unit (FEMCU) IGBT temperature sensor
  • Front electric motor control unit (FEMCU) capacitor temperature sensor
  • Front electric motor control unit (FEMCU) control module temperature sensor
  • Rear electric motor control unit (REMCU) current sensor
  • Rear electric motor control unit (REMCU) coil temperature sensor
  • Rear electric motor control unit (REMCU) position sensor
  • Rear electric motor control unit (REMCU) IGBT temperature sensor
  • Rear electric motor control unit (REMCU) capacitor temperature sensor
  • Rear electric motor control unit (REMCU) control module temperature sensor
  • Front electric motor control unit (FEMCU) inverter voltage sensor
  • Rear electric motor control unit (REMCU) inverter voltage sensor
 
 
DTC SET CONDITIONS
Logic Flow Chart
Check Conditions
  • The charging contactor activation command on.
  • The main contactor (P) activation command off.
  • The main contactor (N) activation command off.
  • Time after above conditions satisfy is 0.4 second.
Judgment Criterion
  • Change of the front electric motor control unit (FEMCU) voltage is more than 60 volts for immediately.
  • Change of the rear electric motor control unit (REMCU) voltage is more than 60 volts for immediately.
 
 
OBD-II DRIVE CYCLE PATTERN
  • Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 3 .
 
 
PROBABLE CAUSES
  • Damaged harness or connector.
  • Malfunction of charge contactor.*
  • Malfunction of main contactor (N) (weld).*
  • Malfunction of electric heater.*
  • Malfunction of the A/C compressor.*
  • Malfunction of the on board charger/DC-DC converter.*
  • Malfunction of the FEMCU.*
  • Malfunction of the REMCU.*
  • Malfunction of the GCU.*
  • Malfunction of the AC converter. <Vehicles with AC power supply>*
  • Malfunction of the PHEV-ECU.
note*: Welding is caused when the high voltage circuit of the high voltage components stays on.
 
 
DIAGNOSIS
Required Special Tools
  • MB991223: Wiring harness set
  • MB992006: Extra fine probe
STEP 1. Check the signal line for short to power supply circuit (PHEV-ECU connector and main drive lithium-ion battery connector).
(1) Disconnect the connector and measure at the harness connector side.
(2) Check the wiring harness between PHEV-ECU connector and the main drive lithium-ion battery connector (terminal CNT-).
Is the check result normal?
Go to Step 2.
Repair the connector or wiring harness. Then go to Step 7.
 
STEP 2. Voltage measurement at high-voltage, service plug connector
danger
  • Carry out the check on the high-voltage circuit while reading carefully the precautions on handling a high-voltage vehicle.
  • Be sure to wear the specified protective equipment when removing the service plug.
(1) Remove the service plug (Refer to ).
(2) Connect a high-voltage compatible multimeter between the main drive lithium-ion battery high-voltage terminal (REMCU) and the main drive lithium-ion battery service plug rear terminal.
OK: Approximately 0 volt
Is the check result normal?
Go to Step 6.
Replace the contactor (Refer to GROUP 54Dc - Main Drive Lithium-ion Battery Disassembly and Assembly, 15. Front JB Assembly, Front JB Bus Bars (D, E, F, N and P), Electric Current Sensor, Contactor and Resistor Removal and Installation ). Then go to Step 3.
 
STEP 3. Using scan tool (M.U.T.-IIISE), check whether the other DTC is set.
Check whether the other DTC, which is associated with the FEMCU, the GCU, the REMCU, the inverter (incorporated in the on-board charger/DC-DC converter), is set in the PHEV-ECU (Refer to ).
Is any DTC set?
Troubleshoot for the relevant DTC. Then go to Step 7.
Go to Step 4.
 
STEP 4. Using scan tool (M.U.T.-IIISE), check whether the other DTC is set.
Check whether DTC is set in the A/C-ECU, A/C compressor assembly and electric heater-ECU (Refer to GROUP 55 - Diagnostic Trouble Code Chart <A/C-ECU>, <A/C compressor assembly>, <electric heater-ECU>).
Is the DTC set?
Troubleshoot for the relevant DTC. Then go to Step 7.
Go to Step 5.
 
STEP 5. Check the electric heater ON failure.
danger
  • Carry out the check on the high-voltage circuit while reading carefully the precautions on handling a high-voltage vehicle.
  • Wear the specified protection equipment during the check.
(1) Remove the service plug (Refer to ).
(2) Disconnect the electric heater connector (high voltage) and measure at the equipment side.
(3) Measure the resistance between electric heater connector (high voltage) (terminal No.1 and No.2).
OK: No continuity (Reference value: 1 MΩ or more)
noteIf you mistake the polarity of the tester, you can not measure correctly.
Is the check result normal?
Go to Step 6.
Check the high-voltage fuse No.5 (Refer to GROUP 54Db - Check and Replacement of The High-voltage Fuse Inside The Inverter ). Replace the electric heater (Refer to GROUP 55 - Heater ). Then go to Step 7.
 
STEP 6. Test the OBD-II drive cycle.
(1) Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 3 .
(2) Check the DTC.
Is the DTC set?
Replace the PHEV-ECU (Refer to ). Then go to Step 7.
The trouble can be an intermittent malfunction (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).
 
STEP 7. Test the OBD-II drive cycle.
(1) Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 3 .
(2) Check the DTC.
Is the DTC set?
Retry the troubleshooting.
The procedure is complete.