Lexus NX: Drive Motor "A" Inverter Performance (P0A78-279)

DTC SUMMARY

MALFUNCTION DESCRIPTION

These DTCs indicate that an overvoltage in the inverter has occurred. The cause of this malfunction may be one of the following:

Internal inverter malfunction
  • Inverter internal circuit malfunction
  • Malfunction in the sensors for inverter control (current sensor, voltage sensor (VH), etc.)

DESCRIPTION

For a description of the inverter.

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If a malfunction occurs in the motor inverter, generator inverter or rear motor inverter, the MG ECU detects it and transmits this information to the hybrid vehicle control ECU.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

MIL

Warning Indicate

P0A78-279

Drive Motor "A" Inverter Performance

Motor inverter overvoltage signal detected (overvoltage (inverter malfunction)):

Overvoltage is detected after boosting.*

(1 trip detection logic)

  • Inverter with converter assembly
  • Wire harness or connector

Comes on

Master Warning Light:

Comes on

*: The cause of the malfunction is most likely a malfunction in the voltage sensors (VL, VH) or the current sensor in the inverter with converter assembly.

Related Data List

DTC No.

Data List

P0A78-279

VH-Voltage after Boosting

MONITOR DESCRIPTION

If the motor inverter detects overvoltage, it will transmit an overvoltage signal to the MG ECU. Then the MG ECU will send information about the malfunction to the hybrid vehicle control ECU. Upon receiving this information, the hybrid vehicle control ECU will illuminate the MIL and store a DTC.

MONITOR STRATEGY

Related DTCs

P0A78 (INF 279): OVH detection (overvoltage malfunction)

Required sensors/components

Rear motor inverter, Motor inverter

Frequency of operation

Continuous

Duration

TMC's intellectual property

MIL operation

1 driving cycle

Sequence of operation

None

TYPICAL ENABLING CONDITIONS

The monitor will run whenever the following DTCs are not stored

TMC's intellectual property

Other conditions belong to TMC's intellectual property

-

TYPICAL MALFUNCTION THRESHOLDS

TMC's intellectual property

-

COMPONENT OPERATING RANGE

Hybrid vehicle control ECU

DTC P0A78 (INF 279) is not detected

CONFIRMATION DRIVING PATTERN

  1. Connect the Techstream to the DLC3.
  2. Turn the power switch on (IG) and turn the Techstream on.
  3. Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
  4. Turn the power switch off and wait for 30 seconds or more.
  5. Turn the power switch on (IG) and turn the Techstream on.
  6. Turn the power switch on (READY).
  7. With the shift lever in P, wait for 5 seconds or more. [A]

    HINT:

    Check that there are no abnormalities (abnormal sounds, coolant leaks, etc.).

  8. Perform a road test according to the freeze frame data item "Vehicle Spd" for approximately 10 minutes. [B]
  9. Enter the following menus: Powertrain / Hybrid Control / Trouble Codes. [C]
  10. Read the current DTCs.

    HINT:

    • If a current DTC is output, the system is malfunctioning.
    • If current DTCs are not output, perform the following steps to check for permanent DTCs.
  11. Check that the permanent DTCs are cleared.
  12. If the permanent DTCs are not cleared, perform a universal trip, and then check for permanent DTCs again.

CAUTION / NOTICE / HINT

CAUTION:

  • Before inspecting the high-voltage system or disconnecting the low voltage connector of the inverter with converter assembly, take safety precautions such as wearing insulated gloves and removing the service plug grip to prevent electrical shocks. After removing the service plug grip, put it in your pocket to prevent other technicians from accidentally reconnecting it while you are working on the high-voltage system.
  • After removing the service plug grip, wait for at least 10 minutes before touching any of the high-voltage connectors or terminals. After waiting for 10 minutes, check the voltage at the terminals in the inspection point in the inverter with converter assembly. The voltage should be 0 V before beginning work.

    Click here

    HINT:

    Waiting for at least 10 minutes is required to discharge the high-voltage capacitor inside the inverter with converter assembly.

NOTICE:

After turning the power switch off, waiting time may be required before disconnecting the cable from the negative (-) auxiliary battery terminal. Therefore, make sure to read the disconnecting the cable from the negative (-) auxiliary battery terminal notices before proceeding with work.

Click here

HINT:

After the repair, clear the DTCs and perform the following procedure to check that DTCs are not output.

  1. With the engine stopped, the power switch on (READY) and the shift lever in P, depress the accelerator pedal to start the engine.

PROCEDURE

1.

CHECK DTC OUTPUT (HYBRID CONTROL)

(a) Connect the Techstream to the DLC3.

(b) Turn the power switch on (IG).

(c) Enter the following menus: Powertrain / Hybrid Control / Trouble Codes.

(d) Check for DTCs.

Powertrain > Hybrid Control > Trouble Codes

Result

Proceed to

P0A78-279 only is output, or DTCs except the ones in the table below are also output.

A

Any of the following DTCs including pending DTCs are also output.

B

Malfunction Content

Relevant DTC

Microcomputer malfunction

P0A1A-151, 166, 658, 791

Generator Control Module

P0A1B-198, 786, 794

Drive Motor "A" Control Module

P0A1C-709, 710, 713, 797

Drive Motor "B" Control Module

P0A1D (all INF codes)*

Hybrid Powertrain Control Module

P1C2A-155

Generator A/D Converter Circuit

P1C2B-192

Drive Motor "A" A/D Converter Circuit

P1C2C-706

Drive Motor "B" A/D Converter Circuit

P1CA6-156

Generator Control Module Malfunction

P1CA7-193

Drive Motor Control Module Malfunction

P1CA8-708

Drive Motor "B" Control Module Malfunction

P1CAC-200

Generator Position Sensor Angle Malfunction

P1CAD-168

Drive Motor "A" Position Sensor Angle Malfunction

P1CAE-715

Drive Motor "B" Position Sensor Angle Malfunction

P1CAF-792

Generator Position Sensor REF Signal Cycle Malfunction

P1CB0-795

Drive Motor "A" Position Sensor REF Signal Cycle Malfunction

P1CB1-798

Drive Motor "B" Position Sensor REF Signal Cycle Malfunction

P1CB2-793

Generator Position Sensor REF Signal Stop Malfunction

P1CB3-796

Drive Motor "A" Position Sensor REF Signal Stop Malfunction

P1CB4-799

Drive Motor "B" Position Sensor REF Signal Stop Malfunction

P3133-659

Communication Error from Generator to Drive Motor "A"

P3134-661

Communication Error from Drive Motor "A" to Generator

Power source circuit malfunction

P06B0-163

Sensor Power Supply "A" Circuit / Open

P06D6-511

Sensor Reference Voltage "F" Circuit / Open

P06E6-164

Sensor Power Supply "C" Circuit / Open

P1C73-512

Sensor Standard Voltage "F" Circuit / Open

Sensor and actuator circuit malfunction

P0A3F-243

Drive Motor "A" Position Sensor Circuit

P0A40-500

Drive Motor "A" Position Sensor Circuit Range / Performance

P0A41-245

Drive Motor "A" Position Sensor Circuit Low

P0A45-669

Drive Motor "B" Position Sensor Circuit

P0A46-671

Drive Motor "B" Position Sensor Circuit Range / Performance

P0A47-670

Drive Motor "B" Position Sensor Circuit Low

P0A4B-253

Generator Position Sensor Circuit

P0A4C-513

Generator Position Sensor Circuit Range / Performance

P0A4D-255

Generator Position Sensor Circuit Low

P0A93-346

Inverter Cooling System Performance

P0BEA-290

Drive Motor "A" Phase V Current Sensor Circuit Range / Performance

P0BEE-298

Drive Motor "A" Phase W Current Sensor Circuit Range / Performance

P0BF6-683

Drive Motor "B" Phase V Current Sensor Circuit Range / Performance

P0BFA-685

Drive Motor "B" Phase W Current Sensor Circuit Range / Performance

P0C73-776

Motor Electronics Coolant Pump "A" Control Performance

P0E05-328

Generator Phase V Current Sensor Circuit Range / Performance

P0E09-336

Generator Phase W Current Sensor Circuit Range / Performance

P1C3C-294

Drive Motor "A" Phase V Current Sensor Correlation

P1C3D-302

Drive Motor "A" Phase W Current Sensor Correlation

P1C3E-333

Generator Phase V Current Sensor Correlation

P1C3F-341

Generator Phase W Current Sensor Correlation

P1C4A-288

Drive Motor "A" Phase V Current Sensor Sub Circuit Range / Performance

P1C4F-296

Drive Motor "A" Phase W Current Sensor Sub Circuit Range / Performance

P1C54-326

Generator Phase V Current Sensor Sub Circuit Range / Performance

P1C59-334

Generator Phase W Current Sensor Sub Circuit Range / Performance

P1C6D-501

Drive Motor "A" Phase V Current Sensor Offset Range / Performance

P1C6E-502

Drive Motor "A" Phase W Current Sensor Offset Range / Performance

P1C6F-688

Drive Motor "B" Phase V Current Sensor Offset Range / Performance

P1C70-689

Drive Motor "B" Phase W Current Sensor Offset Range / Performance

P1C71-515

Generator Phase V Current Sensor Offset Range / Performance

P1C72-516

Generator Phase W Current Sensor Offset Range / Performance

P314A-828

Inverter Coolant Pump Speed Signal

P33C1-684

Drive Motor "B" Phase V Current Sensor Sub Circuit Range / Performance

P33C6-686

Drive Motor "B" Phase W Current Sensor Sub Circuit Range / Performance

P33D8-677

Drive Motor "B" Phase V Current Sensor Correlation

P33D9-678

Drive Motor "A" Phase W Current Sensor Correlation

System malfunction

P0A1A-517, 809

Generator Control Module

P0A1B-505, 554, 806

Drive Motor "A" Control Module

P0A1C-169, 693, 812

Drive Motor "B" Control Module

P0A40-506, 556, 808

Drive Motor "A" Position Sensor Circuit Range / Performance

P0A46-171, 695, 814

Drive Motor "B" Position Sensor Circuit Range / Performance

P0A4C-518, 811

Generator Position Sensor Circuit Range / Performance

P0A78-287, 555, 807

Drive Motor "A" Inverter Performance

P0A79-170, 694, 813

Drive Motor "B" Inverter Performance

P0A7A-325, 810

Generator Inverter Performance

P0ADB-227

Hybrid Battery Positive Contactor Control Circuit Low

P0ADC-226

Hybrid Battery Positive Contactor Control Circuit High

P0ADF-229

Hybrid Battery Negative Contactor Control Circuit Low

P0AE0-228

Hybrid Battery Negative Contactor Control Circuit High

P0C76-523

Hybrid Battery System Discharge Time Too Long

P0D2E-586

Drive Motor "A" Inverter Voltage Sensor Circuit Range / Performance

P0D2F-266

Drive Motor "A" Inverter Voltage Sensor Circuit Low

P0D30-267

Drive Motor "A" Inverter Voltage Sensor Circuit High

P0E32-585

DC/DC Converter Voltage Sensor "A" Range / Performance

P0E33-589

DC/DC Converter Voltage Sensor "A" Low

P0E34-590

DC/DC Converter Voltage Sensor "A" High

P1C2D-587

Hybrid Battery Voltage / DC/DC Converter Voltage Correlation

P3004-803

High Voltage Power Resource

HINT:

  • *1: If any INF codes are output for this DTC, refer to the corresponding diagnostic procedure.
  • P0A78-279 may be output as a result of the malfunction indicated by the DTCs above.
    1. The chart above is listed in inspection order of priority.
    2. Check DTCs that are output at the same time by following the listed order. (The main cause of the malfunction can be determined without performing unnecessary inspections.)

(e) Turn the power switch off.

B

GO TO DTC CHART (HYBRID CONTROL SYSTEM)

A

2.

CHECK CONNECTOR CONNECTION CONDITION (INVERTER WITH CONVERTER ASSEMBLY CONNECTOR)

Click here

Result

Proceed to

OK

A

NG (The connector is not connected securely.)

B

NG (The terminals are not making secure contact or are deformed, or water or foreign matter exists in the connector.)

C

A

REPLACE INVERTER WITH CONVERTER ASSEMBLY

B

CONNECT SECURELY

C

REPAIR OR REPLACE HARNESS OR CONNECTOR

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