Lexus NX manuals

Lexus NX: Inverter Low-voltage Circuit

Lexus NX Service Manual / Engine & Hybrid System / 2ar-fxe (hybrid / Battery Control) / Hybrid Control System / Inverter Low-voltage Circuit

DESCRIPTION

The cause of the malfunction may be the low-voltage circuit.

Check whether there is an open circuit in the inverter +B low-voltage power source system or a problem in the communication between the hybrid vehicle control ECU and inverter.

Related Parts Check

Area

Inspection

Step

Inverter +B low-voltage power source system check

Check for inverter overcurrent malfunction.

1, 2

Communication malfunction between hybrid vehicle control ECU and MG-ECU inside inverter with converter assembly

Check for inverter overcurrent malfunction due to communication malfunction.

3, 4

Check for short to ground in inverter +B low-voltage power source system

-

5, 6, 7

WIRING DIAGRAM

CAUTION / NOTICE / HINT

This step is referenced from the procedures for each DTC.

If the inspection results below are normal, perform the next procedure for the referenced DTC.

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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PROCEDURE

1.

CHECK FUSE (PCU)

(a) Remove the PCU fuse from the No. 1 engine room relay block.

*1

No. 1 Engine Room Relay Block

*2

PCU Fuse

(b) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection

Condition

Specified Condition

PCU fuse terminal

Always

Below 1 Ω

(c) Install the PCU fuse.

NG

GO TO STEP 5

OK

2.

CHECK HARNESS AND CONNECTOR (INVERTER WITH CONVERTER ASSEMBLY POWER SOURCE CIRCUIT)

CAUTION:

Be sure to wear insulated gloves.

(a) Check that the service plug grip is not installed.

NOTICE:

After removing the service plug grip, do not turn the power switch on (READY), unless instructed by the repair manual because this may cause a malfunction.

(b) Disconnect the A58 inverter with converter assembly connector.

Click here

(c) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection

Condition

Specified Condition

A58-10 (GND1) - Body ground

Power switch off

Below 1 Ω

A58-11 (GND2) - Body ground

Power switch off

Below 1 Ω

*a

Front view of wire harness connector

(to Inverter with Converter Assembly)

(d) Connect the cable to the negative (-) auxiliary battery terminal.

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

(f) Measure the voltage according to the value(s) in the table below.

Standard Voltage:

Tester Connection

Condition

Specified Condition

A58-30 (+B) - Body ground

Power switch on (IG)

Same as auxiliary battery voltage

A58-31 (+B2) - Body ground

Power switch on (IG)

Same as auxiliary battery voltage

NOTICE:

Turning the power switch on (IG) with the inverter with converter assembly connector disconnected causes other DTCs to be stored. Clear the DTCs after performing this inspection.

(g) Turn the power switch off.

(h) Disconnect the cable from the negative (-) auxiliary battery terminal.

(i) Reconnect the A58 inverter with converter assembly connector.

NG

REPAIR OR REPLACE POWER SOURCE CIRCUIT
OK

3.

CHECK HARNESS AND CONNECTOR (HYBRID VEHICLE CONTROL ECU - INVERTER WITH CONVERTER ASSEMBLY)

CAUTION:

Be sure to wear insulated gloves.

(a) Check that the service plug grip is not installed.

NOTICE:

After removing the service plug grip, do not turn the power switch on (READY), unless instructed by the repair manual because this may cause a malfunction.

(b) Disconnect the A58 inverter with converter assembly connector.

(c) Disconnect the A61 hybrid vehicle control ECU connector.

(d) Measure the resistance according to the value(s) in the table below.

Standard Resistance (Check for Open):

Tester Connection

Condition

Specified Condition

A58-9 (HTM+) - A61-24 (HTM+)

Power switch off

Below 1 Ω

A58-20 (HTM-) - A61-25 (HTM-)

Power switch off

Below 1 Ω

A58-8 (MTH+) - A61-23 (MTH+)

Power switch off

Below 1 Ω

A58-19 (MTH-) - A61-22 (MTH-)

Power switch off

Below 1 Ω

A58-26 (REQ+) - A61-31(REQ+)

Power switch off

Below 1 Ω

A58-37 (REQ-) - A61-30 (REQ-)

Power switch off

Below 1 Ω

A58-7 (CLK+) - A61-33 (CLK+)

Power switch off

Below 1 Ω

A58-18 (CLK-) - A61-32 (CLK-)

Power switch off

Below 1 Ω

Standard Resistance (Check for Short):

Tester Connection

Condition

Specified Condition

A58-9 (HTM+) or A61-24 (HTM+) - Body ground and other terminals

Power switch off

10 kΩ or higher

A58-20 (HTM-) or A61-25 (HTM-) - Body ground and other terminals

Power switch off

10 kΩ or higher

A58-8 (MTH+) or A61-23 (MTH+) - Body ground and other terminals

Power switch off

10 kΩ or higher

A58-19 (MTH-) or A61-22 (MTH-) - Body ground and other terminals

Power switch off

10 kΩ or higher

A58-26 (REQ+) or A61-31(REQ+) - Body ground and other terminals

Power switch off

10 kΩ or higher

A58-37 (REQ-) or A61-30 (REQ-) - Body ground and other terminals

Power switch off

10 kΩ or higher

A58-7 (CLK+) or A61-33 (CLK+) - Body ground and other terminals

Power switch off

10 kΩ or higher

A58-18 (CLK-) or A61-32 (CLK-) - Body ground and other terminals

Power switch off

10 kΩ or higher

*a

Front view of wire harness connector

(to Inverter with Converter Assembly)

*b

Rear view of wire harness connector

(to Hybrid Vehicle Control ECU)

(e) Connect the cable to the negative (-) auxiliary battery terminal.

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

(g) Measure the voltage according to the value(s) in the table below.

Standard Voltage:

Tester Connection

Condition

Specified Condition

A58-9 (HTM+) or A61-24 (HTM+) - Body ground

Power switch on (IG)

Below 1 V

A58-20 (HTM-) or A61-25 (HTM-) - Body ground

Power switch on (IG)

Below 1 V

A58-8 (MTH+) or A61-23 (MTH+) - Body ground

Power switch on (IG)

Below 1 V

A58-19 (MTH-) or A61-22 (MTH-) - Body ground

Power switch on (IG)

Below 1 V

A58-26 (REQ+) or A61-31(REQ+) - Body ground

Power switch on (IG)

Below 1 V

A58-37 (REQ-) or A61-30 (REQ-) - Body ground

Power switch on (IG)

Below 1 V

A58-7 (CLK+) or A61-33 (CLK+) - Body ground

Power switch on (IG)

Below 1 V

A58-18 (CLK-) or A61-32 (CLK-) - Body ground

Power switch on (IG)

Below 1 V

NOTICE:

Turning the power switch on (IG) with the hybrid vehicle control ECU and inverter with converter assembly connectors disconnected causes other DTCs to be stored. Clear the DTCs after performing this inspection.

(h) Turn the power switch off.

(i) Disconnect the cable from the negative (-) auxiliary battery terminal.

(j) Reconnect the A61 hybrid vehicle control ECU connector.

(k) Reconnect the A58 inverter with converter assembly connector.

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

4.

CHECK HYBRID VEHICLE CONTROL ECU

(a) Disconnect the A61 hybrid vehicle control ECU connector.

(b) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection

Condition

Specified Condition

A61-24 (HTM+) - A61-25 (HTM-)

Power switch off

80 to 170 Ω

A61-23 (MTH+) - A61-22 (MTH-)

Power switch off

80 to 170 Ω

A61-31 (REQ+) - A61-30 (REQ-)

Power switch off

80 to 170 Ω

A61-33 (CLK+) - A61-32 (CLK-)

Power switch off

80 to 170 Ω

*a

Component without harness connected

(Hybrid Vehicle Control ECU)

(c) Reconnect the A61 hybrid vehicle control ECU connector.

OK

INVERTER LOW-VOLTAGE CIRCUIT NORMAL (PERFORM NEXT STEP FOR REFERENCED DTC)
NG

REPLACE HYBRID VEHICLE CONTROL ECU

5.

CHECK HARNESS AND CONNECTOR (INVERTER WITH CONVERTER ASSEMBLY - PCU FUSE)

CAUTION:

Be sure to wear insulated gloves.

(a) Check that the service plug grip is not installed.

NOTICE:

After removing the service plug grip, do not turn the power switch on (READY), unless instructed by the repair manual because this may cause a malfunction.

(b) Disconnect the A58 inverter with converter assembly connector.

Click here

(c) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection

Condition

Specified Condition

A58-30 (+B) - Body ground

Power switch off

10 kΩ or higher

A58-31 (+B2) - Body ground

Power switch off

10 kΩ or higher

*a

Front view of wire harness connector

(to Inverter with Converter Assembly)

(d) Reconnect the A58 inverter with converter assembly connector.

NG

GO TO STEP 7

OK

6.

REPLACE INVERTER WITH CONVERTER ASSEMBLY

Click here

NEXT

REPLACE FUSE (PCU)

7.

REPAIR OR REPLACE HARNESS OR CONNECTOR
NEXT

REPLACE FUSE (PCU)

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