Lexus NX: Steering Lock does not Lock

Lexus NX Service Manual / Steering / Steering Column / Steering Lock System / Steering Lock does not Lock

DESCRIPTION

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

When the steering lock is operating, the steering may not lock when the lock bar is not aligned with the lock hole of the steering column. In this case, the steering can be locked by turning the steering wheel a little, as is done for a vehicle with a mechanical key, to change the position of the lock hole.

Related Data List and Active Test Items

Problem Symptom	Data List Item	Active Test Item
Steering Lock does not Lock	Smart Access Lock Request Receive S Code Check L Code Check Steering Lock Main Body FL Door Courtesy SW Power Source Control Shift P Signal	-

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

When using the Techstream with the power 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 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.
Perform either of the following operations to lock/unlock the steering:
- To unlock the steering, carry the key and turn the power switch on (ACC) or on (IG).
- To lock the steering, turn the power switch off with the shift lever in P, and then open a door.
Make sure that no DTCs are output. If any DTCs are output, proceed to the Diagnostic Trouble Code Chart.
Click here
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
When replacing the steering lock ECU (steering lock actuator assembly), certification ECU (smart key ECU assembly) or ID code box (immobiliser code ECU), registration must be performed.
Click here
After performing repairs, confirm that the problem does not recur.
Inspect the fuses for circuits related to this system before performing the following procedure.
After the power switch is turned off, there may be a waiting time before disconnecting the negative (-) auxiliary battery terminal.
Click here
When disconnecting and reconnecting the auxiliary battery
Click here

HINT:

When disconnecting and reconnecting the auxiliary battery, there is an automatic learning function that completes learning when the respective system is used.

Click here

PROCEDURE

1.	READ VALUE USING TECHSTREAM (LOCK REQUEST RECEIVE)

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

Body Electrical > Smart Access > Data List

Tester Display	Measurement Item	Range	Normal Condition	Diagnostic Note
Lock Request Receive	Lock request signal received state	OK or NG	OK: Lock request signal received for 10 seconds of any of the doors being opened with shift lever in P and power switch off. NG: Except above	If OK is not displayed even though the steering lock conditions are met, the certification ECU (smart key ECU assembly) may be malfunctioning.

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Lock Request Receive

Lock request signal received state

OK or NG

OK: Lock request signal received for 10 seconds of any of the doors being opened with shift lever in P and power switch off.

NG: Except above

If OK is not displayed even though the steering lock conditions are met, the certification ECU (smart key ECU assembly) may be malfunctioning.

Body Electrical > Smart Access > Data List

Tester Display
Lock Request Receive

OK:

The certification ECU (smart key ECU assembly) receives a lock request signal within 10 seconds of turning the power switch from on (IG) to off and opening a door with the shift lever in P, and OK is displayed on the Techstream screen.

GO TO STEP 10

2.	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 NG is displayed: 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 hybrid control system cannot be started).

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 NG is displayed:

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 hybrid control system 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.

GO TO STEP 9

3.	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 assembly)	OK or NG	OK: Verification result normal NG: Verification result abnormal	When NG is displayed: The ID code for the ID code box (immobiliser code ECU) or steering lock ECU (steering lock actuator assembly) is not registered, or the ID code box (immobiliser code ECU) or steering lock ECU (steering lock actuator assembly) is malfunctioning. The steering cannot be locked. The steering cannot be unlocked (the hybrid control system cannot be started).

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 assembly)

OK or NG

OK: Verification result normal

NG: Verification result abnormal

When NG is displayed:

The ID code for the ID code box (immobiliser code ECU) or steering lock ECU (steering lock actuator assembly) is not registered, or the ID code box (immobiliser code ECU) or steering lock ECU (steering lock actuator assembly) is malfunctioning.
The steering cannot be locked.
The steering cannot be unlocked (the hybrid control system 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 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.

GO TO STEP 8

4.	CHECK HARNESS AND CONNECTOR (POWER SOURCE TERMINAL)

(a) Disconnect the I2 steering lock ECU (steering lock actuator assembly) connector.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
I2-1 (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
I2-7 (B) - Body ground	Always	11 to 14 V

*a	Front view of wire harness connector (to Steering Lock ECU (Steering Lock Actuator Assembly))

REPAIR OR REPLACE HARNESS OR CONNECTOR

5.	INSPECT STEERING LOCK ECU (STEERING LOCK ACTUATOR ASSEMBLY)

(a) Reconnect the I2 steering lock ECU (steering lock actuator assembly) connector.

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

Standard Frequency:

Item	Content
Tester Connection	I2-3 (IGE) - I2-1 (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 power switch on (ACC) or on (IG).
- To lock the steering, turn the power switch off with the shift lever in P, and then open a door.

Component with harness connected

(Steering Lock ECU (Steering Lock Actuator Assembly))

Steering Lock Motor not Operating

Steering Lock Motor Operating

Result	Proceed to
OK (for Manual tilt and manual telescopic steering column)	A
OK (for Power tilt and power telescopic steering column)	B
NG	C

REPLACE STEERING LOCK ECU (STEERING LOCK ACTUATOR ASSEMBLY)

6.	CHECK HARNESS AND CONNECTOR (STEERING LOCK ECU (STEERING LOCK ACTUATOR 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 I2 steering lock ECU (steering lock actuator 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
I2-3 (IGE) - I53-24 (SLR+)	Always	Below 1 Ω
I2-3 (IGE) - Body ground	Always	10 kΩ or higher
I53-24 (SLR+) - Body ground	Always	10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

7.	INSPECT STEERING LOCK ECU (STEERING LOCK ACTUATOR ASSEMBLY)

(a) Reconnect the I2 steering lock ECU (steering lock actuator assembly) connector.

(b) Reconnect the I53 certification ECU (smart key ECU assembly) connector.

Standard Voltage:

Tester Connection	Condition	Specified Condition
I2-3 (IGE) - Body ground	Always	11 to 14 V

*a	Component with harness connected (Steering Lock ECU (Steering Lock Actuator Assembly))

Result	Proceed to
OK	A
NG (for Manual tilt and manual telescopic steering column)	B
NG (for Power tilt and power telescopic steering column)	C

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

REPLACE STEERING LOCK ACTUATOR ASSEMBLY

8.	REPLACE STEERING LOCK ECU (STEERING LOCK ACTUATOR ASSEMBLY)

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

for Manual tilt and manual telescopic steering column: Click here

(b) Replace the steering lock ECU (steering lock actuator assembly) with a new one.

for Power tilt and power telescopic steering column: Click here

Click here

(d) 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 assembly)

OK or NG

OK: Verification result normal

NG: Verification result abnormal

When NG is displayed:

The ID code for the ID code box (immobiliser code ECU) or steering lock ECU (steering lock actuator assembly) is not registered, or the ID code box (immobiliser code ECU) or steering lock ECU (steering lock actuator assembly) is malfunctioning.
The steering cannot be locked.
The steering cannot be unlocked (the hybrid control system cannot be started).

Body Electrical > Smart Access > Data List

Tester Display
L Code Check

OK:

OK is displayed on the Techstream.

END

REPLACE ID CODE BOX (IMMOBILISER CODE ECU)

9.	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

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 NG is displayed:

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 hybrid control system cannot be started).

Body Electrical > Smart Access > Data List

Tester Display
S Code Check

OK:

OK is displayed on the Techstream.

END

REPLACE ID CODE BOX (IMMOBILISER CODE ECU)

10.	READ VALUE USING TECHSTREAM (DOOR COURTESY SW)

(a) Using the Techstream, check the following main body ECU (multiplex network body ECU) Data List item by opening and closing the driver door to confirm the state of the front door courtesy light switch assembly.

Body Electrical > Main Body > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

FL Door Courtesy SW

Front door courtesy light switch assembly LH

ON or OFF

ON: Front door LH open

OFF: Front door LH closed

If this item does not change according to the actual state of the driver door, there is a malfunction in the door courtesy light switch or a related part.

Body Electrical > Main Body > Data List

Tester Display
FL Door Courtesy SW

OK:

The Data List item changes in accordance with the opening and closing of the driver door.

GO TO LIGHTING SYSTEM (DOOR COURTESY SWITCH CIRCUIT)

11.	READ VALUE USING TECHSTREAM (SHIFT P SIGNAL)

(a) Move the shift lever to P.

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

Body Electrical > Power Source Control > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Shift P Signal

Shift position (P) signal

ON or OFF

ON: Shift lever in P

OFF: Shift lever not in P

Use this item to determine whether the shift lever position switch (P) is malfunctioning.

Body Electrical > Power Source Control > Data List

Tester Display
Shift P Signal

OK:

ON is displayed on the Techstream.

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

12.	READ VALUE USING TECHSTREAM (STEERING LOCK)

(a) Check that the steering is unlocked.

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

Body Electrical > Smart Access > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Steering Lock

Steering lock ECU (steering lock actuator assembly) unlock confirmation status

Unset or Set

Unset: Unlock not confirmed

Set: Unlock confirmed

When Unset is displayed, the steering is not unlocked (the hybrid control system cannot be started).

Body Electrical > Smart Access > Data List

Tester Display
Steering Lock

OK:

Set is displayed on the Techstream.

Result	Proceed to
OK	A
NG (for Manual tilt and manual telescopic steering column)	B
NG (for Power tilt and power telescopic steering column)	C

REPLACE STEERING LOCK ECU (STEERING LOCK ACTUATOR ASSEMBLY)

13.	READ VALUE USING TECHSTREAM (LOCK REQUEST RECEIVE)

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

Click here

(b) Perform registration.

Click here

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

Body Electrical > Smart Access > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Lock Request Receive

Lock request signal received state

OK or NG

OK: Lock request signal received for 10 seconds of any of the doors being opened with shift lever in P and power switch off.

NG: Except above

If OK is not displayed even though the steering lock conditions are met, the certification ECU (smart key ECU assembly) may be malfunctioning.

Body Electrical > Smart Access > Data List

Tester Display
Lock Request Receive

OK:

The certification ECU (smart key ECU assembly) receives a lock request signal within 10 seconds of turning the power switch from on (IG) to on (ACC) or off and opening a door with the shift lever in P, and OK is displayed on the Techstream screen.

END

REPLACE ID CODE BOX (IMMOBILISER CODE ECU)

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