Lexus NX: Only Back Door cannot be Opened

DESCRIPTION

The main body ECU (multiplex network body ECU) receives signals from the back door opener switch assembly. Then, the main body ECU (multiplex network body ECU) activates the back door lock motor.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

  • When using the Techstream with the vehicle power switch off, connect the Techstream to the DLC3 and turn a courtesy light switch on and off at intervals of 1.5 seconds or less until communication between the Techstream and the vehicle begins. Then select Model Code "KEY REGIST" under manual mode and enter the following menus: Body Electrical / Entry&Start(CAN). While using the Techstream, periodically turn a courtesy light switch on and off at intervals of 1.5 seconds or less to maintain communication between the Techstream and the vehicle.
  • Inspect the fuses for circuits related to this system before performing the following procedure.
  • If the main body ECU (multiplex network body ECU) is replaced, refer to the Smart Access System with Push-button Start (for Entry Function).

    Click here

  • The power door lock control system uses the CAN communication system. Inspect the communication function by following How to Proceed with Troubleshooting. Troubleshoot the power door lock control system after confirming that the communication systems are functioning properly.

    Click here

PROCEDURE

1.

PERFORM ACTIVE TEST USING TECHSTREAM (Trunk and Back-Door Open)

(a) Connect the Techstream to the DLC3.

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

(c) Turn the Techstream on.

(d) Enter the following menus: Body Electrical / Main Body / Active Test.

(e) Perform the Active Test according to the display on the Techstream.

Body Electrical > Main Body > Active Test

Tester Display

Measurement Item

Control Range

Diagnostic Note

Trunk and Back-Door Open

Back door lock motor

OFF/ON

-

Body Electrical > Main Body > Active Test

Tester Display

Trunk and Back-Door Open

OK:

The back door lock assembly unlatches when ON is selected.

OK

GO TO SMART ACCESS SYSTEM WITH PUSH-BUTTON START (for Entry Function)

NG

2.

INSPECT BACK DOOR LOCK ASSEMBLY

(a) Remove the back door lock assembly.

Click here

(b) Inspect the back door lock assembly.

Click here

NG

REPLACE BACK DOOR LOCK ASSEMBLY

OK

3.

CHECK HARNESS AND CONNECTOR (BACK DOOR LOCK ASSEMBLY - INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY AND BODY GROUND)

(a) Disconnect the Y13 back door lock assembly connector.

(b) Disconnect the 4A instrument panel junction block assembly connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

Y13-1 (ACT+) - 4A-25

Always

Below 1 Ω

Y13-3 (D+) - 4A-21

Always

Below 1 Ω

Y13-2 (ACT-) - Body ground

Always

Below 1 Ω

Y13-1 (ACT+) or 4A-25 - Body ground

Always

10 kΩ or higher

Y13-3 (D+) or 4A-21 - Body ground

Always

10 kΩ or higher

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

4.

INSPECT INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY

(a) Remove the instrument panel junction block assembly.

Click here

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

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

*a

Component without harness connected

(Instrument Panel Junction Block Assembly)

-

-

Standard Resistance:

Tester Connection

Condition

Specified Condition

A-4 (BCTY) - 4A-21

Always

Below 1 Ω

NG

REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY

OK

5.

CHECK INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY (D/L BACK RELAY)

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

*a

Front view of wire harness connector

(to Instrument Panel Junction Block Assembly)

-

-

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

4A-25 - 4D-9

Auxiliary battery voltage applied to terminals 4F-1 and A-6

10 kΩ or higher

4A-25 - 4D-9

Auxiliary battery voltage not applied to terminals 4F-1 and A-6

Below 1 Ω

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

4A-25 - Auxiliary battery negative (-) terminal

Auxiliary battery voltage applied to terminals 4F-1 and A-6

11 to 14 V

OK

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

NG

REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY

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 Installation

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 Inspection

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