Lexus NX: Open / Short in Steering Lock ECU (B2781)

Lexus NX Service Manual / Steering / Steering Column / Steering Lock System / Open / Short in Steering Lock ECU (B2781)

DESCRIPTION

The steering lock ECU and steering lock motor are built into the steering lock actuator assembly.

The steering lock ECU (steering lock actuator assembly) detects whether the steering lock is in the lock or unlock position by using the lock sensor and unlock sensor of the steering lock motor.

The steering lock ECU (steering lock actuator assembly) receives lock and unlock request signals from the certification ECU (smart key ECU assembly) and responds with lock and unlock operation signals.

HINT:

The steering lock ECU (steering lock actuator assembly) is not connected to the CAN communication system. However, the steering lock ECU (steering lock actuator assembly) is connected to the certification ECU (smart key ECU assembly) via LIN communication and communicates with other components via CAN communication through the certification ECU (smart key ECU assembly).

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	Note
B2781	Open / Short in Steering Lock ECU	One of the following conditions is met (1-trip detection logic1): The steering lock sensor or unlock sensor is malfunctioning.2 The steering lock motor activation circuit has a short circuit. The steering lock motor activation circuit has an open circuit.	Steering lock ECU (Steering lock actuator assembly) LIN communication system	DTC Output Confirmation Operation: No confirmation operation is necessary (monitoring is continuous).

*1: Only output while a malfunction is present and the power switch is on (IG).
*2: When both detection switches turn on, the system is determined to be malfunctioning.

Vehicle Condition and Fail-safe Function when Malfunction Detected

Vehicle Condition when Malfunction Detected	Fail-safe Function when Malfunction Detected
The steering cannot be locked or unlocked. For this reason, the hybrid control system cannot be started.	Prohibits the hybrid control system from being started (the hybrid control system does not crank).

Related Data List and Active Test Items

DTC No.	Data List Item	Active Test Item
B2781	Smart Access Sensor Value Motor Driver Short	-

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.
After performing repairs, confirm that no DTCs are output again.
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When replacing the steering lock ECU (steering lock actuator assembly), registration must be performed.
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HINT:

When all the ECUs that are connected via LIN communication cannot communicate with the certification ECU (smart key ECU assembly), DTC B2785 is stored.

PROCEDURE

CHECK DTC

(a) Using the Techstream, check if LIN communication DTC B2785 is output.

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HINT:

If a LIN communication DTC is output, perform troubleshooting for the LIN communication system.

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Result	Proceed to
DTC B2785 is output.	A
DTC B2785 is not output (for Manual tilt and manual telescopic steering column).	B
DTC B2785 is not output (for Power tilt and power telescopic steering column).	C

GO TO LIN COMMUNICATION SYSTEM (DTC B2785)

REPLACE STEERING LOCK ECU (STEERING LOCK ACTUATOR ASSEMBLY)

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Removal

REMOVAL PROCEDURE 1. REMOVE CONSOLE ARMREST ASSEMBLY Click here 2. REMOVE UPPER REAR CONSOLE PANEL Click here 3. REMOVE UPPER NO. 2 CONSOLE PANEL GARNISH Click here 4. REMOVE INSTRUMENT SIDE PANEL LH Click here 5. REMOVE NO. 1 INSTRUMENT PANEL SAFETY PAD SUB-ASSEMBLY Click here 6

Hybrid Battery Precharge Contactor Circuit Stuck Closed (P0AE2-773)

DTC SUMMARY MALFUNCTION DESCRIPTION The hybrid vehicle control ECU detects a stuck closed malfunction of a precharge relay stuck malfunction on the HV battery negative side. The cause of this malfunction may be one of the following: Inside of inverter voltage sensor (VH) circuit malfunction Volta

Lexus NX: Open / Short in Steering Lock ECU (B2781)

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Removal

Hybrid Battery Precharge Contactor Circuit Stuck Closed (P0AE2-773)