Beeping sound at start up

[Afterburner]

TOYOTA KLUGER GSU45R 3.5L 2GR-FE DOHC-PB 24v MPFI V6 4dr Wagon 5sp Auto AWD [08/07 - 11/13]

 

Looking for advice on a double beep that occurs after the initial key turn to initiate start up. I have reset the ECU and reprogrammed the keys. Commercially available obd2 readers return no error codes. Despite this I have a irregularly occurrence of a double beep that once is active, stops only when the ignition is switched off.

l’ll post a link with a video reflecting the sound in a subsequent post. Feel free to ignore the Dropbox link if you have malware concerns. The sound is similar to when engaging reverse gear, yet it eminates from the front of the vehicle. 

I think it’s connected to the anti theft/immobiliser/key fob and have it booked in for a diagnostic.

no error codes return, no warning lights are on. Sound present regardless of seatbelt and door postures. Sound persists when engaging reverse gear/ changing gears 

https://www.dropbox.com/s/hqpb0pwo37hxskc/Video 4-4-2022%2C 1 02 37 pm.mp4?dl=0