Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual: Security Indicator Light Does not Blink

Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual / Vehicle Interior / Theft Deterrent / Keyless Entry / Immobiliser System / Security Indicator Light Does not Blink

DESCRIPTION

  • The certification ECU (smart key ECU assembly) blinks the security indicator light (radio receiver assembly) when the immobiliser is set (engine switch off).
  • The certification ECU (smart key ECU assembly) receives the security indicator light signal from the main body ECU (multiplex network body ECU) via CAN communication when the theft deterrent system is in the arming preparation state or alarm sounding state. Then, the certification ECU (smart key ECU assembly) blinks the security indicator light (radio receiver assembly).

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

  • 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 Registration.

    Click here

PROCEDURE

1.

CHECK FOR DTC

(a) Check for DTCs.

Body Electrical > Smart Access > Trouble Codes Powertrain > Engine > Trouble Codes

OK:

DTCs are not output.

NG

GO TO DIAGNOSTIC TROUBLE CODE CHART

OK

2.

PERFORM ACTIVE TEST USING TECHSTREAM (IMMOBILISER INDICATOR)

(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 / Smart Access / Active Test.

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

Body Electrical > Smart Access > Active Test

Tester Display

Measurement Item

Control Range

Diagnostic Note

Immobiliser Indicator

Security indicator light

OFF/ON

-
Body Electrical > Smart Access > Active Test

Tester Display

Immobiliser Indicator

OK:

The security indicator light (radio receiver assembly) operates normally.

NG

GO TO STEP 4

OK

3.

CHECK SECURITY INDICATOR LIGHT (RADIO RECEIVER ASSEMBLY) OPERATION

(a) When the immobiliser is set, check that the security indicator light (radio receiver assembly) blinks.*1

OK:

The security indicator light (radio receiver assembly) blinks normally.

(b) When the theft deterrent system is in the arming preparation state, check that the security indicator light (radio receiver assembly) illuminates.*2

OK:

The security indicator light (radio receiver assembly) illuminates normally.

Result

Proceed to

*1 is NG (*2 is OK)

A

*2 is NG (*1 is OK)

B
A

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

B

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

4.

CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) - SECURITY INDICATOR LIGHT (RADIO RECEIVER ASSEMBLY))

(a) Disconnect the J41 certification ECU (smart key ECU assembly) connector.

(b) Disconnect the J151 security indicator light (radio receiver assembly) connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

J41-20 (IND) - J151-12 (SEUC)

Always

Below 1 Ω

J41-20 (IND) or J151-12 (SEUC) - Body ground

Always

10 kΩ or higher
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

5.

CHECK CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

(a) Reconnect the J41 certification ECU (smart key ECU assembly) connector.

(b) Reconnect the J151 security indicator light (radio receiver assembly) connector.

(c) Using an oscilloscope, check the waveform.

*a

Component with harness connected

(Certification ECU (Smart Key ECU Assembly))

-

-

Measurement Condition:

Tester Connection

Condition

Specified Condition

J41-20 (IND) - Body ground

Engine switch off → on (IG)

Pulse generation → Below 2 V
OK

REPLACE SECURITY INDICATOR LIGHT (RADIO RECEIVER ASSEMBLY)

NG

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

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