Lexus RX (RX 350L, RX450h) 2016-2024 Repair Manual: Entry Exterior Alarm and Answer-back Buzzer do not Sound

DESCRIPTION

The smart access system with push-button start (for Entry Function) uses the wireless door lock buzzer to perform various vehicle exterior warnings. When the conditions of each warning are met, the certification ECU (smart key ECU assembly) sends a buzzer activation request signal to the main body ECU (multiplex network body ECU) via CAN communication and the buzzer sounds.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

  • The smart access system with push-button start (for Entry Function) uses the LIN communication system and CAN communication system. Inspect the communication function by following How to Proceed with Troubleshooting. Troubleshoot the smart access system with push-button start (for Entry Function) after confirming that the communication systems are functioning properly.

    Click here

  • When using the Techstream with the engine 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 the vehicle type under manual mode and enter the following menus: Body Electrical / Smart Access. 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.
  • Before replacing the certification ECU (smart key ECU assembly) or main body ECU (multiplex network body ECU), refer to Precaution.

    Click here

  • After repair, confirm that no DTCs are output.

PROCEDURE

1.

CHECK CUSTOMIZE SETTING (WIRELESS BUZZER RESP)

(a) Connect the Techstream to the DLC3.

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

(c) Turn the Techstream on.

(d) Enter the following menus: Customize Setting / Wireless Door Lock.

Wireless Door Lock

Tester Display

Description

Default

Setting

ECU

Wireless Buzzer Resp

Wireless buzzer response

ON

0:OFF,1:ON

Main body ECU (multiplex network body ECU)

Result

Proceed to

"ON" is displayed

A

"OFF" is displayed

B

B

PERFORM CUSTOMIZE SETTING

A

2.

CHECK WIRELESS DOOR LOCK CONTROL SYSTEM

(a) Check that the function operates normally.

Click here

Result

Proceed to

Wireless door lock function operates normally

A

Wireless door lock function does not operate normally

B

B

GO TO PROBLEM SYMPTOMS TABLE

A

3.

READ VALUE USING TECHSTREAM (EACH UNLOCK DETECTION SWITCH)

(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 / Main Body / Data List.

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

Body Electrical > Main Body > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

FR Door Lock Pos

Front door RH unlock detection switch signal

UNLOCK or LOCK

UNLOCK: Front door RH unlocked

LOCK: Front door RH locked

-

FL Door Lock Pos

Front door LH unlock detection switch signal

UNLOCK or LOCK

UNLOCK: Front door LH unlocked

LOCK: Front door LH locked

-

RR-Door Lock Pos SW

Rear door RH unlock detection switch signal

ON or OFF

ON: Rear door RH unlocked

OFF: Rear door RH locked

-

RL-Door Lock Pos SW

Rear door LH unlock detection switch signal

ON or OFF

ON: Rear door LH unlocked

OFF: Rear door LH locked

-

Body Electrical > Main Body > Data List

Tester Display

FR Door Lock Pos

FL Door Lock Pos

RR-Door Lock Pos SW

RL-Door Lock Pos SW

OK:

The Techstream display changes correctly in response to the lock/unlock operation.

NG

GO TO LIGHTING SYSTEM (Proceed to Door Unlock Detection Switch Circuit)

OK

4.

PERFORM ACTIVE TEST USING TECHSTREAM (WIRELESS BUZZER)

(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 / Main Body / Active Test.

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

Body Electrical > Main Body > Active Test

Tester Display

Measurement Item

Control Range

Diagnostic Note

Wireless Buzzer

Wireless door lock buzzer

OFF/ON

-

Body Electrical > Main Body > Active Test

Tester Display

Wireless Buzzer

Result

Proceed to

Wireless door lock buzzer does not sound

A

Wireless door lock buzzer sounds

B

B

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

A

5.

CHECK WIRELESS DOOR LOCK BUZZER

(a) Disconnect the A58 wireless door lock buzzer connector.

(b) Connect the Techstream to the DLC3.

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

(d) Turn the Techstream on.

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

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

Body Electrical > Main Body > Active Test

Tester Display

Measurement Item

Control Range

Diagnostic Note

Wireless Buzzer

Wireless door lock buzzer

OFF/ON

-

Body Electrical > Main Body > Active Test

Tester Display

Wireless Buzzer

(g) While performing the Active Test, measure the voltage between the terminals of the wireless door lock buzzer.

Standard Voltage:

Tester Connection

Condition

Specified Condition

A58-1 (B) - A58-2 (E)

Active Test Wireless Buzzer ON

Pulse generation

(frequency: 2 kHz, high voltage: 11 to 14 V, low voltage: below 1 V)

Active Test Wireless Buzzer OFF

Below 1 V

*a

Front view of wire harness connector

(to Wireless Door Lock Buzzer)

OK

REPLACE WIRELESS DOOR LOCK BUZZER

NG

6.

CHECK HARNESS AND CONNECTOR (WIRELESS DOOR LOCK BUZZER - MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) AND BODY GROUND)

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

Click here

(b) Disconnect the A58 wireless door lock buzzer connector.

(c) Reconnect the 2C instrument panel junction block assembly connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

A58-1 (B) - MB-21 (BZR)

Always

Below 1 Ω

A58-2 (E) - Body ground

Always

Below 1 Ω

A58-1 (B) or MB-21 (BZR) - Body ground

Always

10 kΩ or higher

OK

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

NG

7.

CHECK HARNESS AND CONNECTOR (WIRELESS DOOR LOCK BUZZER - INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY)

(a) Disconnect the 2C instrument panel junction block assembly connector.

(b) Disconnect the A58 wireless door lock buzzer connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

A58-1 (B) - 2C-29 (BZR)

Always

Below 1 Ω

A58-1 (B) or 2C-29 (BZR) - Body ground

Always

10 kΩ or higher

OK

REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

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