Lexus NX: Taillight Relay Circuit

DESCRIPTION

Illumination of the taillights and license plate light is controlled by the main body ECU (multiplex network body ECU).

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.

PERFORM ACTIVE TEST USING TECHSTREAM (TAILLIGHT RELAY)

(a) Using the Techstream, perform the Active Test.

Click here

Body Electrical > Main Body > Active Test

Tester Display

Measurement Item

Control Range

Diagnostic Note

Taillight Relay

Taillight relay

ON or OFF

-

Body Electrical > Main Body > Active Test

Tester Display

Taillight Relay

Result

Proceed to

Taillights, license lights, clearance light and side marker lights come on

A

Taillights, license lights, clearance light and side marker lights do not come on

B

A

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

B

2.

CHECK HARNESS AND CONNECTOR (INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY - BATTERY)

(a) Disconnect the instrument panel junction block assembly connector.

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

Standard Voltage:

Tester Connection

Switch Condition

Specified Condition

4F-1 - Body ground

Power switch off

11 to 14 V

*a

Front view of wire harness connector

(to Instrument Panel Junction Block Assembly)

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

3.

INSPECT INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY

(a) Remove the instrument panel junction block assembly.

Click here

(b) Remove the instrument panel junction block assembly.

Click here

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

4A-37 - Battery negative (-) terminal

Battery voltage applied between terminals 4F-1 and A-14 (TRLY)

11 to 14 V

Battery voltage not applied between terminals 4F-1 and A-14 (TRLY)

Below 1 V

4A-38 - Battery negative (-) terminal

Battery voltage applied between terminals 4F-1 and A-14 (TRLY)

11 to 14 V

Battery voltage not applied between terminals 4F-1 and A-14 (TRLY)

Below 1 V

4B-24 - Battery negative (-) terminal

Battery voltage applied between terminals 4F-1 and A-14 (TRLY)

11 to 14 V

Battery voltage not applied between terminals 4F-1 and A-14 (TRLY)

Below 1 V

4B-25 - Battery negative (-) terminal

Battery voltage applied between terminals 4F-1 and A-14 (TRLY)

11 to 14 V

Battery voltage not applied between terminals 4F-1 and A-14 (TRLY)

Below 1 V

4B-26 - Battery negative (-) terminal

Battery voltage applied between terminals 4F-1 and A-14 (TRLY)

11 to 14 V

Battery voltage not applied between terminals 4F-1 and A-14 (TRLY)

Below 1 V

OK

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

NG

REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY

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