Lexus NX: System Description

Lexus NX Service Manual / Vehicle Interior / Theft Deterrent / Keyless Entry / Smart Access System With Push-button Start (for Entry Function) / System Description

SYSTEM DESCRIPTION

MULTI CHANNEL FUNCTION

(a) The electrical key transmitter sub-assembly and door control receiver can operate on two different RF channels. When an electrical key transmitter sub-assembly is brought within an exterior detection area, key verification begins. If key verification fails due to wave interference, the channel will be switched and key verification will be performed again.

The multi channel system begins verification using the channel on which the last verification was successfully performed. When verification fails, the system switches to the other channel.

*a	Exterior detection areas are created using LF waves (emitted from the vehicle at intervals of 0.25 seconds) to receive a response from the electrical key transmitter sub-assembly.	*b	When the electrical key transmitter sub-assembly is brought into an exterior detection area, it receives LF waves from the vehicle. Using RF waves, the electrical key transmitter sub-assembly responds to the vehicle.
*c	Upon receiving the response from the electrical key transmitter sub-assembly, the certification ECU (smart key ECU assembly) activates the electrical key antennas (outside) one by one. Using LF waves, the certification ECU (smart key ECU assembly) determines which exterior detection area the electrical key transmitter sub-assembly is in.	*d	The electrical key transmitter sub-assembly receives the LF waves from the vehicle and responds using RF waves. (The certification ECU (smart key ECU assembly) recognizes which exterior detection area the electrical key transmitter sub-assembly is in.)
*e	The certification ECU (smart key ECU assembly) sends registered key ID information to the electrical key transmitter sub-assembly using LF waves. (Up to 7 key IDs can be registered.)	*f	The electrical key transmitter sub-assembly sends the key ID information using RF waves. When the certification ECU (smart key ECU assembly) receives it, verification completes.
*g	Wave interference (Channel switching)	-	-

The multi channel system changes the channels when the RF band (*b, *d and *f) is interrupted by wave interference. Refer to the table below to confirm when the system changes the channels.

	b or d is NG		*f is NG
Condition	RF waves cannot be received	RF waves cannot be received properly	RF waves cannot be received	RF waves cannot be received properly
Channel switching	The channels will not be switched.	The channels will be switched.	The channels will not be switched.	The channels will be switched*.

*: The channels are not switched during vehicle interior verification after an entry lock operation is performed.

SMART ACCESS SYSTEM WITH PUSH-BUTTON START SPECIFICATIONS

(a) Some customers may inquire about the frequency used by the smart access system with push-button start on various models. This repair manual contains the applicable specifications of the smart access system with push-button start.

Transmitter Detection Area

Specifications for Smart Access System with Push-button Start Antenna LF Output Power

	Specification
	Frequency	Output Power/Electric Field Intensity	Modulation Method	Mounting Point in Vehicle
Inside Passenger Compartment	134.2 kHz	94.4 dBuV/m at 3 m	AM	Inside vehicle
Outside Vehicle	134.2 kHz	95 dBuV/m at 3 m	AM	Inside door handle
Outside Vehicle	134.2 kHz	95 dBuV/m at 3 m	AM	Inside rear bumper

Specifications for Smart Access System with Push-button Start Antenna LF Transmission Timing

	Transmission Timing
Vehicle Remains Parked	Entering or Exiting the Vehicle	Vehicle is being Driven
Inside Passenger Compartment	Does not transmit	Operating door locks Operating power switch / depressing brake pedal Opening or closing doors With power switch on (IG) or power switch on (ACC), and shift lever in P, closing any door when electrical key transmitter sub-assembly cannot be detected inside vehicle (continues for 3 seconds until electrical key transmitter sub-assembly is detected or power switch is turned off) Power switch is off after driving for more than 20 minutes With shift lever not in P, closing any door when electrical key transmitter sub-assembly cannot be detected inside vehicle (continues for 3 seconds until electrical key transmitter sub-assembly is detected)	When electrical key transmitter sub-assembly is not detected inside passenger compartment while car is being driven (transmits for 4 seconds)
Outside Vehicle	(1) When door is locked, transmits at 250 ms intervals (stops when door is unlocked) (2) Does not transmit	(1) Touch the lock sensor (2) Pressing back door opener switch assembly (3) Touching unlock sensor in power saving mode	Does not transmit

Transmission Timing

Vehicle Remains Parked

Entering or Exiting the Vehicle

Vehicle is being Driven

Inside Passenger Compartment

Does not transmit

Operating door locks
Operating power switch / depressing brake pedal
Opening or closing doors
With power switch on (IG) or power switch on (ACC), and shift lever in P, closing any door when electrical key transmitter sub-assembly cannot be detected inside vehicle (continues for 3 seconds until electrical key transmitter sub-assembly is detected or power switch is turned off)
Power switch is off after driving for more than 20 minutes
With shift lever not in P, closing any door when electrical key transmitter sub-assembly cannot be detected inside vehicle (continues for 3 seconds until electrical key transmitter sub-assembly is detected)

When electrical key transmitter sub-assembly is not detected inside passenger compartment while car is being driven (transmits for 4 seconds)

Outside Vehicle

(1) When door is locked, transmits at 250 ms intervals (stops when door is unlocked)

(2) Does not transmit

(1) Touch the lock sensor

(2) Pressing back door opener switch assembly

(3) Touching unlock sensor in power saving mode

Does not transmit

BASIC PRECAUTIONS

(a) DTC numbers and ECU Data Lists of the smart access system with push-button start can be checked using the Techstream.

(b) Check for DTCs using the following procedure. If any DTCs are output, diagnose those DTCs first.

(1) Connect the Techstream to the DLC3.

(2) Turn the power switch on (IG).

(3) Enter the following menus: Body Electrical / Smart Access, Power Source Control or Starting Control / Trouble Codes.

(c) When using the Techstream with the power 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.

(d) If cancel is selected for the smart access system with push-button start customize setting, cancel the smart key cancel setting.

Click here

DIAGRAM OF SMART ACCESS SYSTEM WITH PUSH-BUTTON START

SYSTEM DESCRIPTION

The following pattern will be used: "Operation" indicates user operation using the smart access system with push-button start. "Expected operation of the vehicle" indicates how a known good vehicle will react in accordance with each operation. "Suspected Area/Diagnosis" indicates suspected malfunctioning areas and tips for each diagnosis if the vehicle did not react as expected.

(a) Example: Operation No.

Operation	-
Expected operation of the vehicle	-
Waveform or Output Value	-

Suspected Area	Diagnosis
-	-

DIAGNOSIS IN ACCORDANCE WITH USER OPERATION

(a) Operation 1

Operation

Turn the power switch off and lock all the doors, then take the electrical key transmitter sub-assembly approximately 3 m (9.84 ft.) or more away from the vehicle.

HINT:

The detection area of each electrical key antenna (outside) is formed by emitting a periodic LF band request signal every 0.25 seconds. The detection area formed by each front door outside handle assembly (electrical key antenna) has a detection range of approximately 0.7 m (2.30 ft.).

Waveform or Output Value

Pulse generation (I53-4 (CLG1) - I53-11 (E)*)

*: Click here

(b) Operation 2

Operation

Bring the electrical key transmitter sub-assembly within 0.7 m (2.30 ft.) of the driver door.

HINT:

The system is in unlock standby mode when the electrical key transmitter sub-assembly is in the detection area and the key ID code sent by the electrical key transmitter sub-assembly matches the key ID code stored by the certification ECU (smart key ECU assembly). The door unlocks if the unlock sensor is touched by hand with the system in unlock standby mode.

Signal transmission: Certification ECU (smart key ECU assembly) → Door outside handle assembly (electrical key antenna) → Electrical key transmitter sub-assembly → Door control receiver → Certification ECU (smart key ECU assembly) → Main body ECU (multiplex network body ECU)

Expected operation of the vehicle

The electrical key transmitter sub-assembly LED starts blinking. If it does not, check the suspected areas in the following table.

Waveform or Output Value

Pulse generation (I53-4 (CLG1) - I53-11 (E)*)
Pulse generation (I52-18 (RCO) - I53-11 (E)*)
Pulse generation (I52-20 (RDAM) - I53-11 (E)*)
Pulse generation (I52-19 (CSEL) - I53-11 (E)*)

*: Click here

Suspected Area	Diagnosis
Electrical key transmitter sub-assembly	The key ID code sent by the electrical key transmitter sub-assembly does not match the key ID code stored in the certification ECU (smart key ECU assembly). Use another electrical key transmitter sub-assembly to check the operation. If the LED of the electrical key transmitter sub-assembly does not blink when it is brought within 0.7 m (2.30 ft.) of the driver door, perform the following procedure. Press the lock and unlock switches of the electrical key transmitter sub-assembly to check the operation. If the doors can be locked and unlocked, that means the detection area has not been formed. Parts other than the electrical key transmitter sub-assemblies and front door outside handle assemblies may be malfunctioning. If the electrical key transmitter sub-assembly malfunctions, the hybrid control system cannot be started and the power switch cannot be turned on (ACC or IG). Under normal operation, entry warning light is displayed on the multi-information display in the combination meter assembly when the power switch is pressed with the electrical key transmitter sub-assembly in the driver seat area, the shift lever in P and the brake pedal released. If the door cannot be opened, use the mechanical key installed in the electrical key transmitter sub-assembly to open the door. HINT: Before replacing the electrical key transmitter sub-assembly, check if the transmitter battery is depleted. If the door cannot be opened, use the mechanical key installed in the electrical key transmitter sub-assembly to open the door.
Transmitter battery is depleted	Press and hold the lock switch of the electrical key transmitter sub-assembly for 5 seconds and check the number of times that the transmitter LED blinks. If the transmitter LED does not blink or blinks only once or twice, the transmitter battery may be depleted. If the transmitter LED does not blink at all, the electrical key transmitter sub-assembly may be malfunctioning. If the transmitter battery voltage at the time the electrical key transmitter sub-assembly sends a signal drops to 2.2 V or less, "Yes" is displayed for "Key Low Battery" in the Data List. If the transmitter battery voltage drops to 2.0 V or lower, operation cannot be assured. HINT: The output of the electrical key transmitter sub-assembly will decrease if it is in low temperatures. When the transmitter battery is depleted, the hybrid control system cannot be started and the power switch cannot be turned on (ACC or IG). If the electrical key transmitter sub-assembly is held near the power switch, the hybrid control system can be started. Make sure that the transmitter battery type and installation direction are correct.
Wave Interference	If the problem occurs in certain locations or times of day, the possibility of wave interference is high. When the electrical key transmitter sub-assembly is malfunctioning, the transmitter battery is depleted, an electrical key transmitter sub-assembly from another vehicle has been used or wave interference is suspected. "Yes" may be displayed for any of the following Data List items: "Unmatch Code or Form", "No Response", "ID Code Difference" or "Unmatched Vehicle-ID"
Certification ECU (smart key ECU assembly)	-
Main body ECU (multiplex network body ECU)	-
Front door outside handle assembly	Vehicle exterior detection area is not formed properly. If the electrical key transmitter sub-assembly LED does not blink within 0.7 m (2.30 ft.) of the front door outside handle assembly of the driver door, but blinks within 0.7 m (2.30 ft.) of the front passenger door, the front door outside handle assembly of the driver door may be malfunctioning. Even if the vehicle exterior detection area is not formed properly, the power switch can be turned on (ACC) and the hybrid control system can be started. Formation of the vehicle exterior detection area can be confirmed by using the Techstream. Click here Even if the vehicle exterior detection area is not formed properly, the doors can be unlocked by pressing the unlock switch of the electrical key transmitter sub-assembly.
Door Control Receiver	If the door control receiver is malfunctioning, it is not possible to unlock the front passenger door and rear door. If the door control receiver is malfunctioning, it is not possible to unlock the doors by a wireless unlock operation. If the door control receiver is malfunctioning, the hybrid control system cannot be started and the power switch cannot be turned on (ACC or IG) unless in an emergency. Formation of the vehicle exterior detection area can be confirmed by using the Techstream. Click here
Auxiliary Battery is discharged	It may be possible to tell whether the auxiliary battery is discharged by operating the horn.
Others	If the smart access system with push-button start function has been canceled through the customize function, the detection area cannot be formed, therefore the electrical key transmitter sub-assembly LED will not blink even if the electrical key transmitter sub-assembly is brought near a front door outside handle assembly. In the smart access system with push-button start, if the electrical key transmitter sub-assembly is constantly in the exterior detection area of one of the doors, the transmitter battery could be drained. For this reason, if this state continues for longer than 10 minutes, the smart access system with push-button start automatically deactivates the exterior detection area that the electrical key transmitter sub-assembly is in. If the electrical key transmitter sub-assembly is in transmitter battery saving mode, even if it receives LF waves from the vehicle, it does not respond using RF waves, therefore the electrical key transmitter sub-assembly LED does not blink. If the electrical key transmitter sub-assembly is left in the vehicle and the doors are locked using another electrical key transmitter sub-assembly, the electrical key transmitter sub-assembly LED will not blink even if it is brought near a front door outside handle assembly.

Operation	Touch the unlock sensor of the driver door with the electrical key transmitter sub-assembly in the exterior detection area.
Expected operation of the vehicle	While the doors are unlocked, the answer-back is performed at the same time. If they do not, check the suspected areas in the following table.
Waveform or Output Value	Pulse generation (I53-4 (CLG1) - I53-11 (E)) Tester connection (instrument panel junction block assembly (ACT-) - body ground)

*: Click here

Suspected Area	Diagnosis
The suspected parts below overlap with the parts covered in operation 2 for when the electrical key transmitter sub-assembly LED does not blink.	-
Front door outside handle assembly (unlock sensor)	If the doors can be unlocked by touching the unlock sensor of the front passenger door while carrying the electrical key transmitter sub-assembly, the unlock sensor of the driver door may be malfunctioning. Under normal operation, "ON" is displayed for the Data List item "D-Door Touch Sensor" when the unlock sensor is touched.
Door lock/unlock mechanism	If a door cannot be locked/unlocked by operating the door control switch on the door in the cabin, the door lock mechanism is malfunctioning.

(d) Operation 4

Operation

After getting into the vehicle while carrying the electrical key transmitter sub-assembly, close the door and press the power switch once with the shift lever in P while not depressing the brake pedal.

Expected operation of the vehicle

The blinking security indicator light goes off, and then the set immobiliser function cancels, allowing the vehicle to be driven.
The steering is unlocked.

If any of the preceding did not happen, check the suspected areas in the following table.

HINT:

When the power switch is pressed, the indoor electrical key antenna forms a key detection area inside the vehicle and detects the electrical key transmitter sub-assembly in the cabin. The electrical key transmitter sub-assembly sends a key ID code upon receiving a request signal and the electrical key transmitter sub-assembly LED illuminates for a short time. After pressing the power switch, if the key ID code sent by the electrical key transmitter sub-assembly matches the key ID code stored by the certification ECU (smart key ECU assembly), the ACC relay turns on and entry warning light is displayed on the multi-information display in the combination meter assembly. After the power source mode has changed, and L code and S code verification has been completed, the steering will be unlocked and the immobiliser will be inactive. The Data List status of "Immobiliser" will then be changed from "Set" to "Unset".

Signal transmission: Certification ECU (smart key ECU assembly) → Indoor electrical key antenna → Electrical key transmitter sub-assembly → Door control receiver → Certification ECU (smart key ECU assembly)

HINT:

The interior detection area is formed when any of the following conditions are met:

Door is opened.
Within approximately 30 seconds after any of the doors have been opened and closed.
The brake pedal is depressed.
Within approximately 30 seconds after the brake pedal has been depressed.
Right after the power switch is pressed.

Waveform or Output Value

Pulse generation (I52-20 (RDAM) - I53-11 (E)*)
Pulse generation (I53-21 (CLG5) - I53-11 (E)*)
Pulse generation (I51-3 (IG1D) - I53-11 (E)*)

*: Click here

Suspected Area	Diagnosis
Certification ECU (smart key ECU assembly)	-
Wave Interference	If malfunctions occur at a specific location/time, wave interference may be the cause. If wave interference is suspected in the cabin, disconnect all the connectors of electronic devices besides standard equipment, or remove the electronic devices and check for noise.
Indoor electrical key antenna assemblies that form the interior detection areas	If the interior detection areas are not formed properly, the hybrid control system cannot be started and the power switch cannot be turned on (ACC or IG). If the electrical key transmitter sub-assembly is held near the power switch in an emergency, the hybrid control system can be started. Using the Techstream, enter key diagnostic mode to forcibly form the interior detection area. If the electrical key transmitter sub-assembly is brought near the area, short beeps sound. Click here
Power switch	Under normal operation, after the power switch is pressed, "ON" is displayed for the Data List items "Start Switch1" and "Start Switch2".
ID code box (immobiliser code ECU)	In order to unlock the steering, it is necessary for "S Code Check" in the Data List to display "OK". If "S Code Check" displays "OK", the certification ECU (smart key ECU assembly) code and ID code box (immobiliser code ECU) code match.
Park/neutral position switch assembly	Under normal conditions, "Neutral SW/ Clutch SW" in the Data List displays "ON" when the shift lever is moved to P.
Steering lock ECU (steering lock actuator assembly)	If "OK" is displayed for the Data List item "L Code Check" when the power switch is turned on (ACC), power will be supplied to the steering motor for approximately 10 seconds. Then the ECU sends an unlock signal to the steering motor and the Data List item "Unlock Request Receive" temporarily changes from "NG" to "OK". After the steering unlocks, the ECU receives the unlocked signal from the steering motor and the Data List item "Steering Unlock" changes from "Unset" to "Set". In order to unlock the steering, it is necessary that "OK" is displayed for the Data List item "L Code Check" (the ID code stored in the steering lock ECU (steering lock actuator assembly) matches that of the ID code box (immobiliser code ECU))

(e) Operation 5

Operation	Depress the brake pedal with the shift lever in P while carrying an electrical key transmitter sub-assembly.
Expected operation of the vehicle	The entry warning light appears on the multi-information display. If it does not, check the suspected areas in the following table.

Suspected Area	Diagnosis
Stop light switch assembly	If the brake pedal is depressed, "ON" is displayed for the Data List item "Stop Light Switch1".
Certification ECU (smart key ECU assembly)	Start function-Terminals of ECU Click here

Suspected Area

Diagnosis

Stop light switch assembly

If the brake pedal is depressed, "ON" is displayed for the Data List item "Stop Light Switch1".

Certification ECU (smart key ECU assembly)

Start function-Terminals of ECU

Click here

(f) Operation 6

Operation	After getting into the vehicle while carrying the electrical key transmitter sub-assembly, press the power switch with the shift lever in P while depressing the brake pedal.
Expected operation of the vehicle	The hybrid control system starts. If it does not, check the suspected areas in the following table.

Suspected Area	Diagnosis
Steering lock system	Under normal operation, the steering will be unlocked and "ON" is displayed for the Data List item "Steering Unlock Switch".
Auxiliary Battery is discharged	Whether the auxiliary battery is discharged or not can be checked easily by operating the horn.

(g) Operation 7

Operation	Press the power switch.
Expected operation of the vehicle	The hybrid control system stops, the entry warning light illuminates and then goes off and the security indicator light changes from off to blinking.

(h) Operation 8

Operation	Open any of the doors with the power switch off.
Expected operation of the vehicle	The steering locks. If it does not, check the suspected areas in the following table.

Suspected Area	Diagnosis
Steering lock system	-
Door courtesy light switch assembly	When the driver door is opened, "ON" is displayed for the Data List item "FL Door Courtesy SW".

(i) Operation 9

Operation	Touch the lock sensor of the driver door outside handle while carrying the electrical key transmitter sub-assembly.
Expected operation of the vehicle	Answer-back is performed at the same time when the doors are locked.

AUXILIARY BATTERY SAVING FUNCTION

(a) When the smart access system with push-button start is operating, the vehicle performs key detection operations every 0.25 seconds. Therefore, if the vehicle is left as is for a long period of time, the auxiliary battery may become fully discharged. The following controls help reduce the rate at which the auxiliary battery is discharged.

(1) If the smart access system with push-button start is not operated for 5 days or more, periodic signal transmission from the electrical key antennas stops. However, the doors can still be unlocked by touching the unlock sensor of a front door outside handle assembly.

(2) If the smart access system with push-button start is not operated for 14 days or more, the lock and unlock sensors of the front passenger door outside handle assembly are disabled. Therefore, only the unlock sensor of the front door outside handle assembly of the driver door can be used to unlock the doors.

(3) If 10 minutes or more elapse while the electrical key transmitter sub-assembly is in an exterior detection area, the front door outside handle assembly (electrical key antenna) detecting the electrical key transmitter sub-assembly will stop operating.

(b) To restore operation of the smart access system with push-button start, perform any of the following operations.

(1) While carrying the electrical key transmitter sub-assembly, touch the lock or unlock sensor of the front door outside handle assembly of the driver side door and perform a door lock or unlock operation.

(2) Lock or unlock the doors with the wireless operation.

(3) Insert the mechanical key into the door key cylinder of the driver door and lock or unlock the doors.

WIRELESS BUZZER VOLUME ADJUSTMENT FUNCTION

(a) The volume of the wireless buzzer can be changed through the customize function.

HINT:

The volume of the following wireless buzzer operations cannot be adjusted.

Warning function buzzer operations
Customize function buzzer operations
Buzzer operations for key diagnostic mode using the Techstream
Key registration buzzer operations

WARNING FUNCTION

(a) Warning

(1) Situation: The hybrid control system is left starting and the shift lever is in a position other than P when the driver gets out of the vehicle.

There are 2 patterns for this situation.

Pattern 1:

When the hybrid control system is left starting and the shift lever is in a position other than P, the driver opens the door and attempts to get out of the vehicle.