Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual: Open in Front Passenger Side Electrical Antenna Circuit (B27A2)

DESCRIPTION

The certification ECU (smart key ECU assembly) generates a request signal and transmits the signal to the front door outside handle assembly (for front passenger door) (electrical key antenna) at intervals of 0.25 seconds. For the front door outside handle assembly (for front passenger door) (electrical key antenna) to detect when the electrical key transmitter sub-assembly is brought close to the vehicle, a signal requesting a response from the electrical key transmitter sub-assembly is transmitted within approximately 1 m (3.28 ft.) of the front passenger door at intervals of 0.25 seconds. DTC B27A2 is stored by the certification ECU (smart key ECU assembly) when an open is detected between the certification ECU (smart key ECU assembly) and front door outside handle assembly (for front passenger door) (electrical key antenna) (between terminals CLG2 and ANT1, or terminals CG2B and ANT2).

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	Note
B27A2	Open in Front Passenger Side Electrical Antenna Circuit	An open is detected in the circuit between the certification ECU (smart key ECU assembly) and front door outside handle assembly (for front passenger door) (CLG2 - ANT1, CG2B - ANT2) (This is detected by the malfunction detection circuit in the certification ECU (smart key ECU assembly)) (1 trip detection logic*).	Certification ECU (smart key ECU assembly) Front door outside handle assembly (for front passenger door) Harness or connector	Any time

Vehicle Condition and Fail-safe Operation when Malfunction Detected

Vehicle Condition when Malfunction Detected	Fail-safe Operation when Malfunction Detected
Entry lock/unlock operation cannot be performed for front passenger door	-

Related Data List and Active Test

DTC No.	Data List and Active Test
B27A2	Key diagnostic mode can be used to perform troubleshooting

WIRING DIAGRAM

CAUTION / NOTICE / HINT

PROCEDURE

1.	CHECK CONNECTOR CONNECTION

(a) Check that the connectors are properly connected to the certification ECU (smart key ECU assembly) and front door outside handle assembly (for front passenger door).

OK:

Connectors are properly connected.

NG

CONNECT CONNECTORS PROPERLY

OK

2.	CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) - FRONT DOOR OUTSIDE HANDLE ASSEMBLY (FOR FRONT PASSENGER DOOR))

(a) Disconnect the R1 and J41 certification ECU (smart key ECU assembly) connectors.

(b) Disconnect the M11 front door outside handle assembly (for front passenger door) connector.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
R1-15 (CLG2) - M11-4 (ANT1)	Always	Below 1 Ω
R1-14 (CG2B) - M11-5 (ANT2)	Always	Below 1 Ω
J41-18 (E) - Body ground	Always	Below 1 Ω
R1-15 (CLG2) or M11-4 (ANT1) - Body ground	Always	10 kΩ or higher
R1-14 (CG2B) or M11-5 (ANT2) - Body ground	Always	10 kΩ or higher

(d) Reconnect the R1 and J41 certification ECU (smart key ECU assembly) connectors.

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

3.	CHECK CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) (OUTPUT TO FRONT DOOR OUTSIDE HANDLE ASSEMBLY (FOR FRONT PASSENGER DOOR))

*a	Component with harness connected (Certification ECU (Smart Key ECU Assembly))	*b	Waveform 1
*c	Waveform 2	*d	Waveform 3
*e	Waveform 4	-	-

(a) Using an oscilloscope, check the waveform.

OK:

Tester Connection	Condition	Tool Setting	Specified Condition
R1-15 (CLG2) - J41-18 (E)	Procedure: Engine switch off All doors closed Electrical key transmitter sub-assembly not inside vehicle All doors locked through wireless operation (electrical key transmitter sub-assembly brought inside detection area*)	5 V/DIV., 500 ms/DIV.	Pulse generation (See waveform 1)
	Procedure: Engine switch off All doors closed Electrical key transmitter sub-assembly not inside vehicle All doors locked through wireless operation (electrical key transmitter sub-assembly brought outside detection area*)	5 V/DIV., 100 ms/DIV.	Pulse generation (See waveform 2)
R1-14 (CG2B) - J41-18 (E)	Procedure: Engine switch off All doors closed Electrical key transmitter sub-assembly not inside vehicle All doors locked through wireless operation (electrical key transmitter sub-assembly brought inside detection area*)	5 V/DIV., 500 ms/DIV.	Pulse generation (See waveform 3)
	Procedure: Engine switch off All doors closed Electrical key transmitter sub-assembly not inside vehicle All doors locked through wireless operation (electrical key transmitter sub-assembly brought outside detection area*)	5 V/DIV., 100 ms/DIV.	Pulse generation (See waveform 4)

NG

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

OK

4.	REPLACE FRONT DOOR OUTSIDE HANDLE ASSEMBLY (FOR FRONT PASSENGER DOOR)

(a) Replace the front door outside handle assembly (for front passenger door) with a new one or the front door outside handle assembly (for driver door) if it is functioning properly.

Click here

NEXT

5.

CLEAR DTC

(a) Clear the DTCs.

Body Electrical > Smart Access > Clear DTCs

NEXT

6.	CHECK FOR DTC

(a) Check for DTCs.

Body Electrical > Smart Access > Trouble Codes

OK:

DTC B27A2 is not output.

OK

END (FRONT DOOR OUTSIDE HANDLE ASSEMBLY (FOR FRONT PASSENGER DOOR) WAS DEFECTIVE)

NG

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)