WEIRD ELECTRONIC BEEPING NOISE INCREASING IN FREQUENCY WHEN DRIVING (2004 TACOMA 4WD DOUBLE CAB)

Hi everyone,

I just had a very odd thing happen to my 2004 Tacoma (4wd double cab, 250k miles). As soon as I started driving, I started hearing a very faint low electronic beeping noise that increased in intervals the faster I went. As soon as I heard this, I pulled over and was listening for it to try and figure out where it was coming from. When I pulled over, rather than a fast beep beep beep beep, it sort of changed to a slower beep.....beep.....beep, and as soon as I started driving again, it started to increase in speed between beeps again. It wasn't perfectly synchronized with the engine, but moving definitely seemed to increase it's frequency. This lasted for my 5 minute drive home and just a few moments before shutting down, it stopped. It has not done it since. Has anyone ever heard of anything like this?

Thank you ahead of time for any advice or comments!