I tried ELM327 and the ECU was making noises I've never heard

This was my first time trying anything like this. I've only used basic code readers, till now. I had an ELM327 bluetooth dongle in the OBD2 port, the ignition on, and was trying to get the "Car Scanner" app to work. In doing so, there was quite a bit of noise coming from the passenger side, where I assume the ECU is. It's not super loud, but I've never heard what seems to be the ECU making noise. It kind of sounds like computer processing ("thinking") noises. Is that normal or did I just damage the ECU?

Edit: 2001 Tacoma Prerunner 3RZ engine

 

ECUs have no moving parts, therefore they do not make noise.

I'm guessing you either heard a rattle in the climate control system or a pissed off gremlin.

 

Some code readers will flash lights on the dash and you'll hear relays click and little gizmos in the car whirring as it queries each system. I use one on my motorcycle and when it does a scan sometimes you'll hear the fan of the radiator kick on, the fuel pump kick on, purge valves open and close, the ABS pump will vibrate.

 

Thanks for the quick replies, @Rock Lobster and @Vitamins. I edited #1 to add that it's a 2001 Tacoma Prerunner with a 3RZ (and automatic). I have the bed off and the fuel pump electrical connector disconnected. The noise seemed to happen only when trying to figure out the app, and it sure sounded like it came from the glovebox area. The HVAC fan is off. The engine is off. As far as I know, the ELM327 isn't bidirectional, so to me it shouldn't be operating anything.

I've been working on it because the engine quit and hasn't run since, so I can't check if the ECU is okay by running the engine. One of the things I did was check for spark, and it had spark. So, if I put it back together (minor stuff) and it still has spark, does that tell me that the ECU is okay?