Lexus NX: Antenna Coil Open / Short (B2784)

Lexus NX Service Manual / Vehicle Interior / Theft Deterrent / Keyless Entry / Immobiliser System / Antenna Coil Open / Short (B2784)

DESCRIPTION

When an open or short circuit is detected in the transponder key amplifier coil built into the power switch, the certification ECU (smart key ECU assembly) stores this DTC. This DTC is also stored as a past DTC.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	Note
B2784	Antenna Coil Open / Short	The transponder key amplifier coil built into the power switch is open (see below) or shorted (determined by communication with certification ECU (smart key ECU assembly)). (1 trip detection logic*) Terminal AGND, VC5, TXCT or CODE circuit is open (includes disconnection of the power switch). The transponder key amplifier coil built into the power switch is open.	Power switch Certification ECU (smart key ECU assembly) Harness or connector	DTC output confirmation operation: With the shift lever in P and the key held near the power switch, a hybrid control system start operation is performed by pressing and holding the power switch when the transmitter battery is depleted.

*: Only output while a malfunction is present.

Vehicle Condition and Fail-safe Operation when Malfunction Detected

Vehicle Condition when Malfunction Detected	Fail-safe Operation when Malfunction Detected
Hybrid control system cannot be started when transmitter battery is depleted by holding transmitter near power switch and pressing and holding power switch with shift lever in P	-

Related Data List and Active Test

DTC No.	Data List and Active Test
B2784	-

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

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.
Before replacing the certification ECU (smart key ECU assembly), refer to Registration.
Click here
After repair, confirm that no DTCs are output by performing "DTC Output Confirmation Operation."

PROCEDURE

1.	CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) - POWER SWITCH)

(a) Disconnect the I53 certification ECU (smart key ECU assembly) connector.

(b) Disconnect the I16 power switch connector.

Standard Resistance:

Tester Connection	Condition	Specified Condition
I53-15 (VC5) - I16-10 (VC5)	Always	Below 1 Ω
I53-14 (TXCT) - I16-7 (TXCT)	Always	Below 1 Ω
I53-13 (CODE) - I16-8 (CODE)	Always	Below 1 Ω
I53-12 (AGND) - I16-6 (AGND)	Always	Below 1 Ω
I53-15 (VC5) or I16-10 (VC5) - Body ground	Always	10 kΩ or higher
I53-14 (TXCT) or I16-7 (TXCT) - Body ground	Always	10 kΩ or higher
I53-13 (CODE) or I16-8 (CODE) - Body ground	Always	10 kΩ or higher
I53-12 (AGND) or I16-6 (AGND) - Body ground	Always	10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

2.	REPLACE POWER SWITCH

(a) Temporarily replace the power switch with a new or known good one.

Click here

CLEAR DTC

(a) Clear the DTCs.

Body Electrical > Smart Access > Clear DTCs

4.	CHECK FOR DTC

(a) Perform "DTC Output Confirmation Operation" procedure.

(b) Check for DTCs.

Body Electrical > Smart Access > Trouble Codes

OK:

DTC B2784 is not output.

END (POWER SWITCH WAS DEFECTIVE)

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

SEE MORE:

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DESCRIPTION This DTC is stored if the parking assist ECU judges as a result of its self check that a synchronization problem is occurring in the image signal sent from the passenger side television camera assembly to the parking assist ECU. DTC No. Detection Item DTC Detection Condition Tro

Problem Symptoms Table

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Lexus NX: Antenna Coil Open / Short (B2784)

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