DTC B27A5-13: Front Floor Electrical Key Oscillator Circuit Open [10/2022 - ]: Procedure
WARNING: This page is about a different car, the 2025 Lexus RX 350, 2024 Lexus RX 350, and 2023 Lexus RX 350. However, it is still accessible from the selected car via links, so may be relevant.
- CHECK CONNECTOR CONNECTION
- Check that the connectors are properly connected to the certification ECU (smart key ECU assembly) and No. 1 indoor electrical key antenna assembly (front floor).
OK
Connectors are properly connected.
Result
Proceed to OK NG
Result:
NG
CONNECT CONNECTORS PROPERLY
Result:
OK
See step 2
- Check that the connectors are properly connected to the certification ECU (smart key ECU assembly) and No. 1 indoor electrical key antenna assembly (front floor).
- CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) - NO. 1 INDOOR ELECTRICAL KEY ANTENNA ASSEMBLY (FRONT FLOOR))
Pre-procedure1
- Disconnect the C51 certification ECU (smart key ECU assembly) connector.
- Disconnect the C56 No. 1 indoor electrical key antenna assembly (front floor) connector.
- Measure the resistance according to the value(s) in the table below.
Standard Resistance
Tester Connection Condition Specified Condition Result C51-4 (CLG5) - C56-1 (ANTE5) Always Below 1 Ω Ω C51-5 (CG5B) - C56-2 (CLGB) Always Below 1 Ω Ω Result
Proceed to OK NG
Post-procedure1
- Connect the C51 certification ECU (smart key ECU assembly) connector.
Result:
NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
Result:
OK
See step 3
- CHECK CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) (OUTPUT TO NO. 1 INDOOR ELECTRICAL KEY ANTENNA ASSEMBLY (FRONT FLOOR))
- Using an oscilloscope, check the waveform.
*a Component with harness connected
(Certification ECU (Smart Key ECU Assembly))*b Waveform *c For 30 seconds after any door closed *d After 30 seconds or more have elapsed since any door closed OK
Tester Connection Condition Tool Setting Specified Condition C51-4 (CLG5) - C51-29 (E) Procedure: - Ignition switch off
- Electrical key transmitter sub-assembly not inside vehicle
- Within 30 seconds of closing any door
5 V/DIV., 500 ms./DIV. Pulse generation
(See waveform)C51-5 (CG5B) - C51-29 (E) Procedure: - Ignition switch off
- Electrical key transmitter sub-assembly not inside vehicle
- Within 30 seconds of closing any door
5 V/DIV., 500 ms./DIV. Pulse generation
(See waveform)Result
Proceed to OK NG
Result:
OK
REPLACE NO. 1 INDOOR ELECTRICAL KEY ANTENNA ASSEMBLY (FRONT FLOOR). Refer to REMOVAL [10/2022 - ]
Result:
NG
REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY). Refer to REMOVAL [10/2022 - 08/2023] , or refer to REMOVAL [08/2023 - ]
- Using an oscilloscope, check the waveform.