Lexus RX (RX 350L, RX450h) 2016-2024 Repair Manual: Unable to Unlock Steering Wheel (Engine cannot Start)

Lexus RX (RX 350L, RX450h) 2016-2024 Repair Manual / Suspension / Steering Column / Steering Lock System / Unable to Unlock Steering Wheel (Engine cannot Start)

DESCRIPTION

The steering lock actuator or upper bracket assembly activates the steering lock motor and moves the lock bar into the steering column to lock the steering.

The steering may not unlock when the lock bar gets stuck in the lock hole of the steering column. In this case, if the engine switch is turned on (IG) while shaking the steering wheel, as is done for a vehicle with a mechanical key, the lock bar will be unlocked. If the certification ECU (smart key ECU assembly), ID code box (immobiliser code ECU) or ECM is replaced, the system needs to be initialized. Otherwise, the steering cannot be unlocked and the engine cannot be started.

Related Data List and Active Test Items

Problem Symptom

Data List Item

Active Test Item

Unable to unlock steering wheel (Engine cannot start)
Smart Access
  • Unlock Request Receive
  • S Code Check
  • L Code Check
  • Steering Unlock

-

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

  • When using the Techstream with the engine switch off, connect the Techstream to the vehicle 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 Model Code "KEY REGIST" 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.
  • Perform either of the following operations to lock/unlock the steering:
    • To unlock the steering, carry the key and turn the engine switch on (ACC) or on (IG).
    • To lock the steering, turn the engine switch off with the shift lever in P, and then open a door.
  • The steering lock system uses LIN communication. First perform the inspections in "How to Proceed with Troubleshooting" to confirm that there are no communication malfunctions before proceeding with troubleshooting.

    Click here

  • After performing repairs, confirm that the problem does not recur.
  • Make sure that no DTCs are output. If any DTCs are output, proceed to the Diagnostic Trouble Code Chart.

    Click here

  • Inspect the fuses for circuits related to this system before performing the following procedure.
  • When replacing the steering lock ECU (steering lock actuator or upper bracket assembly), certification ECU (smart key ECU assembly) or ID code box (immobiliser code ECU), registration must be performed.

    Click here

  • When disconnecting the cable from the negative (-) battery terminal, some systems need to be initialized after the cable is reconnected.

    Click here

  • If the steering lock ECU (steering lock actuator or upper bracket assembly) is replaced, be sure to confirm that the steering is unlocked by turning the steering wheel to the left and right before starting the engine. This function prevents the engine from starting while the steering is locked. If the steering is locked for any reason, open and close a door with the engine switch off, and then unlock the steering by pressing the engine switch.

PROCEDURE

1.

CHECK ENGINE SWITCH (SWITCH CONDITION)

(a) Check the power source mode change.

(1) When the key is inside the vehicle and the shift lever is in P, check that pressing the engine switch with the brake pedal released causes the power source mode to change as follows:

OK:

Off → On (ACC) → On (IG) → Off

NG

GO TO SMART ACCESS SYSTEM WITH PUSH-BUTTON START (PROBLEM SYMPTOMS TABLE)

OK

2.

CHECK INDICATOR

(a) With the engine switch on (IG), check that Steering Lock active is displayed on the multi-information display in the combination meter assembly.

Result

Proceed to

Steering Lock active is displayed.

A

Steering Lock active is not displayed.

B
B

GO TO STEP 4

A

3.

CHECK STEERING UNLOCK

(a) Turn the steering wheel left and right, and then press the engine switch.

(b) Check that the steering is unlocked.

Result

Proceed to

The steering is unlocked.

A

The steering is not unlocked.

B
A

END
B

4.

CHECK FOR DTC

(a) Using the Techstream, check if the certification ECU (smart key ECU assembly) DTC is output.

Body Electrical > Smart Access > Trouble Codes

Result

Proceed to

DTCs are not output.

A

DTCs are output.

B
B

GO TO DIAGNOSTIC PROCEDURE INDICATED BY OUTPUT DTC
A

5.

READ VALUE USING TECHSTREAM (UNLOCK REQUEST RECEIVE)

(a) Use the Data List to check if the steering lock request is functioning properly.

Body Electrical > Smart Access > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Unlock Request Receive

Reception state of steering unlock request signal by certification ECU (smart key ECU assembly) sent to ID code box (immobiliser code ECU)

HINT:

  • The reception state is maintained for 10 seconds.
  • When 10 seconds or more have elapsed after receiving the signal, the item changes to "NG".

OK or NG

OK: Unlock request received within 10 seconds of turning engine switch on (IG) or on (ACC) or starting engine

NG: Except above
  • If the unlock signal has not been received, the engine cannot be started.
  • If this item does not change to "OK" even though the steering unlock conditions are met, the certification ECU (smart key ECU assembly) may be malfunctioning.
Body Electrical > Smart Access > Data List

Tester Display

Unlock Request Receive

OK:

Within 10 seconds of turning the engine switch on (ACC) or on (IG) or starting the engine, the Data List item changes to "OK".

NG

GO TO STEP 14

OK

6.

READ VALUE USING TECHSTREAM (S CODE CHECK)

(a) Use the Data List to check if S code certification is functioning properly.

Body Electrical > Smart Access > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

S Code Check

Verification result between certification ECU (smart key ECU assembly) and ID code box (immobiliser code ECU)

OK or NG

OK: Verification result normal

NG: Verification result abnormal

When a malfunction is present:

  • The ID code for the certification ECU (smart key ECU assembly) or ID code box (immobiliser code ECU) is not registered or the certification ECU (smart key ECU assembly) or ID code box (immobiliser code ECU) is malfunctioning.
  • The steering cannot be locked.
  • The steering cannot be unlocked (the engine cannot be started).
Body Electrical > Smart Access > Data List

Tester Display

S Code Check

OK:

OK is displayed on the Techstream.

HINT:

Reasons for verification failure:

  • The certification ECU (smart key ECU assembly) or ID code box (immobiliser code ECU) is malfunctioning.
  • There is a problem with the communication between ECUs.
  • An ECU is replaced, but is not registered.
  • An ECU is replaced with an ECU which has a code already stored in it.
NG

GO TO STEP 13

OK

7.

READ VALUE USING TECHSTREAM (L CODE CHECK)

(a) Use the Data List to check if L code certification is functioning properly.

Body Electrical > Smart Access > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

L Code Check

Verification result between ID code box (immobiliser code ECU) and steering lock ECU (steering lock actuator or upper bracket assembly)

OK or NG

OK: Verification result normal

NG: Verification result abnormal

When a malfunction is present:

  • The ID code for the ID code box (immobiliser code ECU) or steering lock ECU (steering lock actuator or upper bracket assembly) is not registered or the ID code box (immobiliser code ECU) or steering lock ECU (steering lock actuator or upper bracket assembly) is malfunctioning.
  • The steering cannot be locked.
  • The steering cannot be unlocked (the engine cannot be started).
Body Electrical > Smart Access > Data List

Tester Display

L Code Check

OK:

OK is displayed on the Techstream.

HINT:

Reasons for verification failure:

  • The steering lock ECU (steering lock actuator or upper bracket assembly) or ID code box (immobiliser code ECU) is malfunctioning.
  • There is a problem with the communication between ECUs.
  • An ECU is replaced, but is not registered.
  • An ECU is replaced with an ECU which has a code already stored in it.
NG

GO TO STEP 12

OK

8.

INSPECT STEERING LOCK ECU (STEERING LOCK ACTUATOR OR UPPER BRACKET ASSEMBLY)

(a) Measure the resistance and voltage according to the value(s) in the table below.

Standard Resistance:

Tester Connection

Condition

Specified Condition

L1-1 (GND) - Body ground

Always

Below 1 Ω

NOTICE:

If the result is not as specified, check for looseness in the ground cable connection.

Standard Voltage:

Tester Connection

Condition

Specified Condition

L1-7 (B) - Body ground

Always

11 to 14 V

*a

Component with harness connected

(Steering Lock ECU (Steering Lock Actuator or Upper Bracket Assembly))
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

9.

CHECK HARNESS AND CONNECTOR (GROUND)

(a) Disconnect the L1 steering lock ECU (steering lock actuator or upper bracket assembly) connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

L1-1 (GND) - Body ground

Always

Below 1 Ω

NOTICE:

If the result is not as specified, check for looseness in the ground cable connection.

*a

Front view of wire harness connector

(to Steering Lock ECU (Steering Lock Actuator or Upper Bracket Assembly))

(c) Check the signal waveform according to the condition(s) in the table below.

Standard Frequency:

Item

Content

Tester Connection

L1-3 (IGE) - L1-1 (GND)

Tool Setting

2 V/DIV., 200 ms./DIV.

Vehicle Condition

Steering lock motor not operating → Operating → Not operating

HINT:

  • When taking measurements when the lock motor is stopped, it is not necessary to perform any operations.
  • In order to take measurements when the lock motor is operating, perform either of the following operations:
    • To unlock the steering, carry the key and turn the engine switch on (ACC) or on (IG).
    • To lock the steering, turn the engine switch off with the shift lever in P, and then open a door.

*a

Component with harness connected

(Steering Lock ECU (Steering Lock Actuator or Upper Bracket Assembly))

*b

Steering Lock Motor not Operating

*c

Steering Lock Motor Operating
OK

REPLACE STEERING LOCK ECU (STEERING LOCK ACTUATOR OR UPPER BRACKET ASSEMBLY)

NG

10.

CHECK HARNESS AND CONNECTOR (STEERING LOCK ECU (STEERING LOCK ACTUATOR OR UPPER BRACKET ASSEMBLY) - CERTIFICATION ECU (SMART KEY ECU ASSEMBLY))

(a) Make sure that there is no looseness at the locking part and the connecting part of the connectors.

(b) Disconnect the L1 steering lock ECU (steering lock actuator or upper bracket assembly) connector.

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

(d) Check for deformation and corrosion of the connector case and terminals.

OK:

There is no deformation or corrosion of the connector case or terminals.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

L1-3 (IGE) - J41-25 (SLR+)

Always

Below 1 Ω

L1-3 (IGE) or J41-25 (SLR+) - Body ground

Always

10 kΩ or higher
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

11.

INSPECT STEERING LOCK ECU (STEERING LOCK ACTUATOR OR UPPER BRACKET ASSEMBLY)

(a) Reconnect the L1 steering lock ECU (steering lock actuator or upper bracket assembly) connector.

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

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

L1-3 (IGE) - Body ground

Always

11 to 14 V

*a

Component with harness connected

(Steering Lock ECU (Steering Lock Actuator or Upper Bracket Assembly))
OK

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

NG

REPLACE STEERING LOCK ECU (STEERING LOCK ACTUATOR OR UPPER BRACKET ASSEMBLY)

12.

REPLACE STEERING LOCK ECU (STEERING LOCK ACTUATOR OR UPPER BRACKET ASSEMBLY)

(a) Replace the steering lock ECU (steering lock actuator or upper bracket assembly) with a new one.

Click here

(b) Perform registration.

Click here

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

(d) Use the Data List to check if L code certification is functioning properly again.

Body Electrical > Smart Access > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

L Code Check

Verification result between ID code box (immobiliser code ECU) and steering lock ECU (steering lock actuator or upper bracket assembly)

OK or NG

OK: Verification result normal

NG: Verification result abnormal

When a malfunction is present:

  • The ID code for the ID code box (immobiliser code ECU) or steering lock ECU (steering lock actuator or upper bracket assembly) is not registered or the ID code box (immobiliser code ECU) or steering lock ECU (steering lock actuator or upper bracket assembly) is malfunctioning.
  • The steering cannot be locked.
  • The steering cannot be unlocked (the engine cannot be started).
Body Electrical > Smart Access > Data List

Tester Display

L Code Check

OK:

OK is displayed on the Techstream.

OK

END
NG

REPLACE ID CODE BOX (IMMOBILISER CODE ECU)

13.

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

(a) Replace the certification ECU (smart key ECU assembly) with a new one.

Click here

(b) Perform registration.

Click here

(c) Use the Data List to check if S code certification is functioning properly.

Body Electrical > Smart Access > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

S Code Check

Verification result between certification ECU (smart key ECU assembly) and ID code box (immobiliser code ECU)

OK or NG

OK: Verification result normal

NG: Verification result abnormal

When a malfunction is present:

  • The ID code for the certification ECU (smart key ECU assembly) or ID code box (immobiliser code ECU) is not registered or the certification ECU (smart key ECU assembly) or ID code box (immobiliser code ECU) is malfunctioning.
  • The steering cannot be locked.
  • The steering cannot be unlocked (the engine cannot be started).
Body Electrical > Smart Access > Data List

Tester Display

S Code Check

OK:

OK is displayed on the Techstream.

OK

END
NG

REPLACE ID CODE BOX (IMMOBILISER CODE ECU)

14.

INSPECT STEERING LOCK ECU (STEERING LOCK ACTUATOR OR UPPER BRACKET ASSEMBLY)

(a) Measure the voltage according to the value(s) in the table below.

Standard Voltage:

Tester Connection

Condition

Specified Condition

L1-4 (SLP1) - Body ground

Steering locked

11 to 14 V

*a

Component with harness connected

(Steering Lock ECU (Steering Lock Actuator or Upper Bracket Assembly))
NG

GO TO STEP 17

OK

15.

READ VALUE USING TECHSTREAM (STEERING UNLOCK)

(a) Check that the steering is locked.

(b) Read the Data List according to the display on the Teshctream.

Body Electrical > Smart Access > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Steering Unlock

State of whether steering lock ECU (steering lock actuator or upper bracket assembly) determined steering is unlocked

Set or Unset

Set: Steering unlocked

Unset: Steering locked

If this item displays "Unset", the steering does not unlock (engine cannot be started).
Body Electrical > Smart Access > Data List

Tester Display

Steering Unlock

OK:

Set is displayed on the Techstream.

NG

REPLACE STEERING LOCK ECU (STEERING LOCK ACTUATOR OR UPPER BRACKET ASSEMBLY)

OK

16.

READ VALUE USING TECHSTREAM (UNLOCK REQUEST RECEIVE)

(a) Replace the certification ECU (smart key ECU assembly) with a new one.

(b) Perform registration.

Click here

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

(d) Use the Data List to check if the steering lock request is functioning properly.

Body Electrical > Smart Access > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Unlock Request Receive

Reception state of steering unlock request signal by certification ECU (smart key ECU assembly) sent to ID code box (immobiliser code ECU)

HINT:

  • The reception state is maintained for 10 seconds.
  • When 10 seconds or more have elapsed after receiving the signal, the item changes to "NG".

OK or NG

OK: Unlock request received within 10 seconds of turning engine switch on (IG) or on (ACC) or starting engine

NG: Except above
  • If the unlock signal has not been received, the engine cannot be started.
  • If this item does not change to "OK" even though the steering unlock conditions are met, the certification ECU (smart key ECU assembly) may be malfunctioning.
Body Electrical > Smart Access > Data List

Tester Display

Unlock Request Receive

OK:

Within 10 seconds of turning the engine switch on (ACC) or on (IG) or starting the engine, the Data List item changes to "OK".

OK

END
NG

REPLACE ID CODE BOX (IMMOBILISER CODE ECU)

17.

CHECK HARNESS AND CONNECTOR (STEERING LOCK ECU (STEERING LOCK ACTUATOR OR UPPER BRACKET ASSEMBLY) - CERTIFICATION ECU (SMART KEY ECU ASSEMBLY))

(a) Make sure that there is no looseness at the locking part and the connecting part of the connectors.

(b) Disconnect the L1 steering lock ECU (steering lock actuator or upper bracket assembly) connector.

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

(d) Check for deformation and corrosion of the connector case and terminals.

OK:

There is no deformation or corrosion of the connector case or terminals.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

L1-4 (SLP1) - J41-14 (SLP)

Always

Below 1 Ω

L1-4 (SLP1) or J41-14 (SLP) - Body ground

Always

10 kΩ or higher
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

18.

READ VALUE USING TECHSTREAM (UNLOCK REQUEST RECEIVE)

(a) Replace the steering lock ECU (steering lock actuator or upper bracket assembly) with a new one.

Click here

(b) Perform registration.

Click here

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

(d) Use the Data List to check if the steering lock request is functioning properly.

Body Electrical > Smart Access > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Unlock Request Receive

Reception state of steering unlock request signal by certification ECU (smart key ECU assembly) sent to ID code box (immobiliser code ECU)

HINT:

  • The reception state is maintained for 10 seconds.
  • When 10 seconds or more have elapsed after receiving the signal, the item changes to "NG".

OK or NG

OK: Unlock request received within 10 seconds of turning engine switch on (IG) or on (ACC) or starting engine

NG: Except above
  • If the unlock signal has not been received, the engine cannot be started.
  • If this item does not change to "OK" even though the steering unlock conditions are met, the certification ECU (smart key ECU assembly) may be malfunctioning.
Body Electrical > Smart Access > Data List

Tester Display

Unlock Request Receive

OK:

Within 10 seconds of turning the engine switch on (ACC) or on (IG) or starting the engine, the Data List item changes to "OK".

OK

END
NG

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

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