- Open or short circuit in the motor, generator or rear motor coils
- An internal motor, generator or rear motor malfunction (iron particles or damage from foreign objects)
Lexus NX: Drive Motor "A" Inverter Performance (P0A78-121)
Lexus NX Service Manual / Engine & Hybrid System / 2ar-fxe (hybrid / Battery Control) / Hybrid Control System / Drive Motor "A" Inverter Performance (P0A78-121)
DTC SUMMARY
MALFUNCTION DESCRIPTION
This DTC indicates that an overvoltage in the inverter has occurred. The cause of this malfunction may be one of the following:
| Area | Main Malfunction Description | Step |
|---|---|---|
| Inverter low-voltage circuit | The connectors are not connected properly | 3 |
| Resolver | Open or short circuit in the motor resolver, generator resolver or rear motor resolver circuit | 4, 5, 6 |
| Motor, generator or rear motor | | 7, 8, 9 |
| HV battery system | High voltage line circuit malfunction | 10 |
| Inverter |
| 11 |
DESCRIPTION
For a description of the inverter.
Click here .gif)
If a malfunction occurs in the motor inverter, generator inverter, rear motor, the MG ECU detects it and transmits this information to the hybrid vehicle control ECU.
HINT:
The term "drive motor A" indicates the motor (MG2).
| DTC No. | Detection Item | DTC Detection Condition | Trouble Area | MIL | Warning Indicate |
|---|---|---|---|---|---|
| P0A78-121 | Drive Motor "A" Inverter Performance | Motor inverter overvoltage signal detected (overvoltage due to system malfunction): Overvoltage is detected after boosting. A malfunction is detected in any of the motor components (motor inverter, motor, MG ECU, etc.).* (1 trip detection logic) |
| Comes on | Master Warning Light: Comes on |
*: This DTC is output when a large voltage is generated by the motor inverter and there is no history information indicating the specific part.
Check related parts (inverter, motor, generator, resolver, cable, wire harness, hybrid vehicle control ECU).
Related Data List| DTC No. | Data List |
|---|---|
| P0A78-121 | 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 121): OVH detection (overvoltage malfunction) |
| Required sensors/components | 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 121) is not detected |
CONFIRMATION DRIVING PATTERN
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- Connect the Techstream to the DLC3.
- Turn the power switch on (IG) and turn the Techstream on.
- Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
- Turn the power switch off and wait for 30 seconds or more.
- Turn the power switch on (IG) and turn the Techstream on.
- Turn the power switch on (READY).
- With the shift lever in P and engine stopped, depress the accelerator pedal to start the engine. [A]
- Enter the following menus: Powertrain / Hybrid Control / Trouble Codes. [B]
-
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.
- Check that the permanent DTCs are cleared.
- If the permanent DTCs are not cleared, perform a universal trip, and then check for permanent DTCs again.
WIRING DIAGRAM
Refer to the wiring diagram for DTC P1CAC-200.
Click here
Refer to the wiring diagram for DTC P0AA6-526.
Click here
Refer to the wiring diagram for DTC P324E-788.
Click here
Refer to the wiring diagram for the inverter low-voltage circuit.
Click here
Refer to the wiring diagram for the HV battery high-voltage line circuit.
Click here
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.
- 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 |
|---|---|
| P0A78-121 is stored before any of the DTCs in the table below are stored. | A |
| Any of the DTCs including pending DTCs in the table below are stored before P0A78-121 is stored. | B |
| Relevant DTC | |
|---|---|
| P0A9C-123 | Hybrid Battery Temperature Sensor "A" Range / Performance |
| P0A9D-123 | Hybrid Battery Temperature Sensor "A" Circuit Low |
| P0A9E-123 | Hybrid Battery Temperature Sensor "A" Circuit High |
| P0AC0-123 | Hybrid Battery Pack Current Sensor Circuit Range / Performance |
| P0AC1-123 | Hybrid Battery Pack Current Sensor Circuit Low |
| P0AC2-123 | Hybrid Battery Pack Current Sensor Circuit High |
| P0AC6-123 | Hybrid Battery Temperature Sensor "B" Range / Performance |
| P0AC7-123 | Hybrid Battery Temperature Sensor "B" Circuit Low |
| P0AC8-123 | Hybrid Battery Temperature Sensor "B" Circuit High |
| P0ACB-123 | Hybrid Battery Temperature Sensor "C" Range / Performance |
| P0ACC-123 | Hybrid Battery Temperature Sensor "C" Circuit Low |
| P0ACD-123 | Hybrid Battery Temperature Sensor "C" Circuit High |
| P0AE9-123 | Hybrid Battery Temperature Sensor "D" Range/Performance |
| P0AEA-123 | Hybrid Battery Temperature Sensor "D" Circuit Low |
| P0AEB-123 | Hybrid Battery Temperature Sensor "D" Circuit High |
| P0AFC-123 | Hybrid Battery Pack Sensor Module |
| P0BC3-123 | Hybrid Battery Temperature Sensor "E" Range/Performance |
| P0BC4-123 | Hybrid Battery Temperature Sensor "E" Circuit Low |
| P0BC5-123 | Hybrid Battery Temperature Sensor "E" Circuit High |
| P0C34-123 | Hybrid Battery Temperature Sensor "F" Range/Performance |
| P0C35-123 | Hybrid Battery Temperature Sensor "F" Circuit Low |
| P0C36-123 | Hybrid Battery Temperature Sensor "F" Circuit High |
| P3011-123, P3012-123, P3013-123, P3014-123, P3015-123, P3016-123, P3017-123, P3018-123, P3019-123, P3020-123, P3021-123, P3022-123, P3023-123, P3024-123, P3025-123, P3026-123, P3027-123 | Battery Block # Becomes Weak |
| P3065-123 | Hybrid Battery Temperature Sensor Range/Performance Stuck "A" |
| P306A-123 | Hybrid Battery Temperature Sensor Range/Performance Stuck "B" |
| P308A-123 | Hybrid Battery Voltage Sensor All Circuits Low |
HINT:
P0A78-121 may be output as a result of the malfunction indicated by the DTCs above.
(e) Turn the power switch off.
| B | .gif) | GO TO DTC CHART (HYBRID BATTERY SYSTEM) |
|
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| 2. | 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 |
|---|---|
| P0A78-121 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-503, 505, 547, 554, 806 | Drive Motor "A" Control Module | |
| P0A1C-118, 124, 169, 693, 812 | Drive Motor "B" Control Module | |
| P0A40-504, 506, 549, 556, 808 | Drive Motor "A" Position Sensor Circuit Range / Performance | |
| P0A46-120, 126, 171, 695, 814 | Drive Motor "B" Position Sensor Circuit Range / Performance | |
| P0A4C-518, 811 | Generator Position Sensor Circuit Range / Performance | |
| P0A78-113, 128, 279, 284, 286, 287, 548, 555, 807 | Drive Motor "A" Inverter Performance | |
| P0A79-119, 125, 136, 170, 692, 694, 696, 712, 813 | Drive Motor "B" Inverter Performance | |
| P0A7A-122, 130, 322, 324, 325, 810 | Generator Inverter Performance | |
| P0A90-509 | Drive Motor "A" Performance | |
| P0A91-702 | Drive Motor "B" Performance | |
| P0A92-521 | Hybrid Generator Performance | |
| P0A94-172, 553, 557 | DC / DC Converter 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 | |
| P0C19-306 | Drive Motor "A" Torque Delivered Performance | |
| P0C1A-704 | Drive Motor "B" Torque Delivered Performance | |
| P0C76-523 | Hybrid Battery System Discharge Time Too Long | |
| P0CA3-442 | DC/DC Converter Step Up Voltage Performance | |
| 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 | |
| P0E71-344 | Generator Torque Delivered Performance | |
| 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.
-
P0A78-121 may be output as a result of the malfunction indicated by the DTCs above.
- The chart above is listed in inspection order of priority.
- 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) |
|
| 3. | 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 |
| B | | CONNECT SECURELY |
| C | | REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
| 4. | CHECK GENERATOR RESOLVER CIRCUIT |
Click here
|
| 5. | CHECK MOTOR RESOLVER CIRCUIT |
Click here
|
| 6. | CHECK REAR MOTOR RESOLVER CIRCUIT |
Click here
|
| 7. | CHECK GENERATOR HIGH-VOLTAGE CIRCUIT |
Click here
|
| 8. | CHECK MOTOR HIGH-VOLTAGE CIRCUIT |
Click here
|
| 9. | CHECK REAR MOTOR HIGH-VOLTAGE CIRCUIT |
Click here
|
| 10. | CHECK HV BATTERY HIGH-VOLTAGE LINE CIRCUIT |
Click here
|
| 11. | CHECK INVERTER LOW-VOLTAGE CIRCUIT |
Click here
HINT:
If the "Inverter Low-voltage Circuit" inspection results are normal, perform the next step.
| NEXT | | REPLACE INVERTER WITH CONVERTER ASSEMBLY |
READ NEXT:
Drive Motor "A" Inverter Performance (P0A78-128)
DTC SUMMARY MALFUNCTION DESCRIPTION This DTC indicates that a large current flowed through the inverter for the motor. The cause of this malfunction may be one of the following: Area Main Malfunc
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In
Drive Motor "A" Inverter Performance (P0A78-284)
DTC SUMMARY MALFUNCTION DESCRIPTION This DTC indicates when the temperature of the inverter for the motor has become abnormal. The cause of this malfunction may be one of the following: Area Main
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Do-it-yourself service precautions
If you perform maintenance by
yourself, be sure to follow the correct
procedure as given in these
sections.
Maintenance
Items
Parts and tools
12-volt battery
condition
Grease
Conventional wrench
(for terminal clamp
bolts)
Brake flui
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