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

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