Lexus NX: Hybrid Battery System Discharge Time Too Long (P0C76-523)

Lexus NX Service Manual / Engine & Hybrid System / 2ar-fxe (hybrid / Battery Control) / Hybrid Control System / Hybrid Battery System Discharge Time Too Long (P0C76-523)

DTC SUMMARY

MALFUNCTION DESCRIPTION

The hybrid vehicle control ECU detects that the electrical charge stored in the high-voltage condenser of the inverter with converter assembly cannot be discharged.

The cause of this malfunction may be one of the following:

Inside of inverter voltage sensor (VH) circuit malfunction
  • Voltage sensor (VH) malfunction
  • Motor generator control ECU (MG ECU) malfunction
  • Communication (wire harness) malfunction
High voltage system malfunction
  • Inverter with converter assembly malfunction
Shutdown signal circuit malfunction
  • Hybrid vehicle control ECU malfunction
  • Wire harness malfunction
  • Inverter with converter assembly malfunction

DESCRIPTION

For a description of the inverter.

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DTC No.

Detection Item

DTC Detection Condition

Trouble Area

MIL

Warning Indicate

P0C76-523

Hybrid Battery System Discharge Time Too Long

The inverter voltage (VH) does not drop during discharge.

(Discharge: Offsetting of the residual pressure in the high-voltage side after power switch is turned off)

(1 trip detection logic)

  • Inverter with converter assembly
  • Wire harness or connector
  • Hybrid vehicle control ECU

Does not come on

Master Warning Light:

Comes on

HINT:

When the power switch is turned from on (READY) to off, the MG ECU discharges voltage stored in the inverter by allowing current to flow to motor (MG2) without generating torque. When the vehicle is normal, VH voltage becomes approximately 0 V after discharging. If VH voltage exceeds a specified value, this DTC is stored.

Related Data List

DTC No.

Data List

P0C76-523

VL-Voltage before Boosting

The following items can be helpful when performing repairs:

Data List
  • Ready Signal

WIRING DIAGRAM

Refer to the wiring diagram for the shut down signal circuit.

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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.

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HINT:

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

  1. Turn the power switch off and wait for 30 seconds or more.
  2. Turn the power switch on (READY) and wait for 30 seconds or more.
  3. Turn the power switch off and wait for 30 seconds or more.

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

P0C76-523 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, 658, 791

Generator Control Module

P0A1B-786

Drive Motor "A" Control Module

P0A1D-148

Hybrid Powertrain Control Module

P1C2A-155

Generator A/D Converter Circuit

P1CA6-156

Generator Control Module Malfunction

P1CA7-193

Drive Motor Control Module Malfunction

P1CAC-200

Generator Position Sensor Angle Malfunction

P1CAD-168

Drive Motor "A" Position Sensor Angle Malfunction

P1CAF-792

Generator Position Sensor REF Signal Cycle Malfunction

P1CB2-793

Generator Position Sensor REF Signal Stop Malfunction

P2511-149

HV CPU Power Relay Sense Circuit Intermittent No Continuity

P3133-659

Communication Error from Generator to Drive Motor "A"

P3134-661

Communication Error from Drive Motor "A" to Generator

P324E-788

MG-ECU Power Relay Intermittent Circuit

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

Communication system malfunction

U0110 (all INF codes)*

Lost Communication with Drive Motor Control Module "A"

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

P0A4B-253

Generator Position Sensor Circuit

P0A4C-513

Generator Position Sensor Circuit Range / Performance

P0A4D-255

Generator Position Sensor Circuit Low

P0ADC-226

Hybrid Battery Positive Contactor Control Circuit High

P0AE0-228

Hybrid Battery Negative Contactor Control Circuit High

P0AE7-224

Hybrid Battery Precharge Contactor Control Circuit High

System malfunction

P0D2F-266

Drive Motor "A" Inverter Voltage Sensor Circuit Low

P0D30-267

Drive Motor "A" Inverter Voltage Sensor Circuit High

HINT:

  • *1: If any INF codes are output for this DTC, refer to the corresponding diagnostic procedure.
  • P0C76-523 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 SHUT DOWN SIGNAL CIRCUIT

Click here

HINT:

If the "Shut Down Signal Circuit" inspection results are normal, perform the next step.

NEXT

REPLACE INVERTER WITH CONVERTER ASSEMBLY

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