DTC B27A5: Open in Front Floor Electrical Key Oscillator Circuit [10/2018 - ]: Procedure
WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2024 Lexus UX 250h, 2023 Lexus UX 250h, 2022 Lexus UX 250h, 2021 Lexus UX 250h, and 2020 Lexus UX 250h. 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))
- Disconnect the F44 certification ECU (smart key ECU assembly) connector.
- Disconnect the F46 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 F44-8 (CLG5) - F46-1 (ANTE5) Always Below 1 Ω F44-9 (CG5B) - F46-3 (CLGB) Always Below 1 Ω - Reconnect the F44 certification ECU (smart key ECU assembly) connector.
Result
Proceed to OK NG
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))
*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 - Using an oscilloscope, check the waveform.
OK
Tester Connection Condition Tool Setting Specified Condition F44-8 (CLG5) - F44-18 (E) Procedure: - Power switch off
- Electrical key transmitter sub-assembly not inside vehicle
- Within 30 seconds of closing any door
2 V/DIV., 500 ms./DIV. Pulse generation
(See waveform)F44-9 (CG5B) - F44-18 (E) Procedure: - Power switch off
- Electrical key transmitter sub-assembly not inside vehicle
- Within 30 seconds of closing any door
2 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 [10/2018 - ]
Result:
NG
REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY). Refer to REMOVAL [10/2018 - 07/2022] Refer to REMOVAL [07/2022 - ]
- Using an oscilloscope, check the waveform.