i have this strange buzzing sound coming from my pcm and im not sure if its something i should worry about. i heard it this morning while i was checking the fluids im my brothers toyota. i opened the dakotas hood and, with no key on and no lights or anything there's a constant audible buzz from inside the computer. has anyone else heard of this before and is it a problem or just annoying.

edit: forgot to add that everything on the truck seems to work just fine, its just the odd noise

 

There are small relays and capacitors and other potential noise makers. Hearing some noise is normal. But what doesn't sound good is that it was making noise when nothing was on, check to see if it is still making the sound every day for a while just to check on it. Don't lift the hood, maybe the little power from the hood light may have something to do with it.

 

thats the thing that was bugging me is i can hear it when the hood is closed and i put my ear close to the fender. it almost sounds like a cicada is stuck in there