Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual: Immobiliser System does not Operate Properly

Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual / Vehicle Interior / Theft Deterrent / Keyless Entry / Immobiliser System / Immobiliser System does not Operate Properly

DESCRIPTION

The immobiliser system compares the ID code that is registered to the certification ECU (smart key ECU assembly) with the ID code of the transponder chip that is embedded in the electrical key transmitter sub-assembly.

WIRING DIAGRAM

Refer to B279986.

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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 ECM or ID code box (immobiliser code ECU), refer to Registration.

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  • After performing repairs, confirm that no DTCs are output by performing "DTC Output Confirmation Operation".

HINT:

If an immobiliser system or SFI system DTC is output, first perform troubleshooting for the immobiliser system or SFI system DTC.

PROCEDURE

1.

CHECK FOR DTC

(a) Check for DTCs.

Body Electrical > Smart Access > Trouble Codes

Result

Proceed to

DTCs are not output

A

DTCs are output

B
B

GO TO DIAGNOSTIC TROUBLE CODE CHART

A

2.

CHECK WHETHER ENGINE STARTS

(a) Check that the engine starts 5 seconds after the engine switch turned on (IG).

OK:

Engine starts normally.

OK

USE SIMULATION METHOD TO CHECK

NG

3.

CHECK HARNESS AND CONNECTOR (ID CODE BOX (IMMOBILISER CODE ECU) - ECM)

(a) Disconnect the J36 ID code box (immobiliser code ECU) connector.

(b) Disconnect the A37 ECM connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

J36-3 (EFII) - A37-45 (IMO)

Always

Below 1 Ω

J36-4 (EFIO) - A37-59 (IMI)

Always

Below 1 Ω

J36-3 (EFII) or A37-45 (IMO) - Body ground

Always

10 kΩ or higher

J36-4 (EFIO) or A37-59 (IMI) - Body ground

Always

10 kΩ or higher
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

4.

REGISTER ECU COMMUNICATION ID

(a) Register the ECU communication ID code.

Click here

NEXT

5.

CHECK WHETHER ENGINE STARTS

(a) Check that the engine starts.

OK:

Engine starts normally.

OK

END (COMMUNICATION ID REGISTRATION WAS DEFECTIVE)
NG

6.

REPLACE ID CODE BOX (IMMOBILISER CODE ECU)

(a) Replace the ID code box (immobiliser code ECU) with a new one.

Click here

NEXT

7.

REGISTER ECU COMMUNICATION ID

(a) Register the ECU communication ID code.

Click here

NEXT

8.

CHECK WHETHER ENGINE STARTS

(a) Check that the engine starts.

OK:

Engine starts normally.

OK

END (ID CODE BOX (IMMOBILISER CODE ECU) WAS DEFECTIVE)
NG

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