Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual: Back Door Closer Switch Malfunction (B2251)

DESCRIPTION

The multiplex network door ECU receives signals from the latch switch, position switch, pawl switch and back door courtesy switch, which are built into the back door lock assembly. Based on these signals, the latch position of the back door lock assembly is determined.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

B2251

Back Door Closer Switch Malfunction

While the back door closer is operating, a malfunction in the position information from the back door courtesy switch is detected within a certain amount of time.

  • Back door lock assembly
  • Multiplex network door ECU
  • Wire harness or connector

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

If the multiplex network door ECU has been removed and installed or replaced, or if any of the connectors have been disconnected, initialize the power back door system.

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PROCEDURE

1.

READ VALUE USING TECHSTREAM

(a) Connect the Techstream to the DLC3.

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

(c) Turn the Techstream on.

(d) Enter the following menus: Body Electrical / Back Door / Data List.

(e) Read the Data List according to the display on the Techstream.

Body Electrical > Back Door > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Half Latch SW

Half-latch switch signal

OFF or ON

OFF: Back door lock motor in full latch or half latch position

ON: Back door lock motor in open latch position

-

Body Electrical > Back Door > Data List

Tester Display

Half Latch SW

OK:

The display is as specified in the normal condition column.

NG

GO TO STEP 3

OK

2.

READ VALUE USING TECHSTREAM

(a) Connect the Techstream to the DLC3.

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

(c) Turn the Techstream on.

(d) Enter the following menus: Body Electrical / Back Door / Data List.

(e) Read the Data List according to the display on the Techstream.

Body Electrical > Back Door > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Courtesy SW

Latch courtesy switch signal

OFF or ON

OFF: Back door closed

ON: Back door open

-

Body Electrical > Back Door > Data List

Tester Display

Courtesy SW

OK:

The display is as specified in the normal condition column.

OK

REPLACE MULTIPLEX NETWORK DOOR ECU

NG

3.

INSPECT BACK DOOR LOCK ASSEMBLY

(a) Remove the back door lock assembly.

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(b) Inspect the back door lock assembly.

Click here

NG

REPLACE BACK DOOR LOCK ASSEMBLY

OK

4.

CHECK HARNESS AND CONNECTOR (BACK DOOR LOCK ASSEMBLY - MULTIPLEX NETWORK DOOR ECU AND BODY GROUND)

(a) Disconnect the Z16 multiplex network door ECU connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

Z7-3 (CLS) - Z16-9 (HAF)

Always

Below 1 Ω

Z7-8 (CTY) - Z16-11 (FUL)

Always

Below 1 Ω

Z7-7 (E) - Body ground

Always

Below 1 Ω

Z7-3 (CLS) or Z16-9 (HAF) - Body ground

Always

10 kΩ or higher

Z7-8 (CTY) or Z16-11 (FUL) - Body ground

Always

10 kΩ or higher

OK

REPLACE MULTIPLEX NETWORK DOOR ECU

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

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