Lexus NX: Interior Light Auto Cut Circuit

DESCRIPTION

The main body ECU (multiplex network body ECU) controls the DOME CUT relay.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

  • Inspect the fuses for circuits related to this system before performing the following procedure.
  • Recognition code registration is necessary when replacing the main body ECU (multiplex network body ECU).
  • If the main body ECU (multiplex network body ECU) is replaced, refer to Registration.

PROCEDURE

1.

READ VALUE USING TECHSTREAM (RELAY FOR INTERIOR LIGHT AUTO CUT FUNCTION)

(a) Using the Techstream, read the Data List.

Click here

Body Electrical > Main Body > Active Test

Tester Display

Measurement Item

Control Range

Diagnostic Note

Relay for Interior Light Auto Cut Function

DOME CUT relay

ON or OFF

Check the operation with the interior illumination on.

Body Electrical > Main Body > Active Test

Tester Display

Relay for Interior Light Auto Cut Function

OK:

Battery saving control (interior light auto cut function) operates.

OK

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

NG

2.

INSPECT DOME CUT RELAY

(a) Remove the DOME CUT relay from the No. 3 relay block.

(b) Inspect the DOME CUT relay.

Click here

NG

REPLACE DOME CUT RELAY

OK

3.

CHECK HARNESS AND CONNECTOR (DOME CUT RELAY - BATTERY)

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

Standard Voltage:

Tester Connection

Switch Condition

Specified Condition

2 - Body ground

Power switch off

11 to 14 V

5 - Body ground

Power switch off

11 to 14 V

*a

Front view of wire harness connector

(to DOME CUT Relay)

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

4.

CHECK HARNESS AND CONNECTOR (DOME CUT RELAY - INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY)

(a) Disconnect the 4C instrument panel junction block assembly connectors.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

DOME CUT relay terminal 1 - 4C-46

Always

Below 1 Ω

DOME CUT relay terminal 1 or 4C-46 - Body ground

Always

10 kΩ or higher

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

5.

INSPECT INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY

(a) Remove the instrument panel junction block assembly.

Click here

*a

Component without harness connected

(Instrument Panel Junction Block Assembly)

(b) Remove the main body ECU (multiplex network body ECU) from the instrument panel junction block assembly.

Click here

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

4C-46 - A-23 (DOMR)

Always

Below 1 Ω

OK

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

NG

REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY

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