Buzzing sound behind dash

[Spetz]

Hi guys,

I connected my battery to my today and there was a buzzing sounds behind the dash (caused by something electrical).
It was fairly loud and it was there regardless of whether the key was in ignition or not.

The thing I noticed is the power door locks would no longer move, so I couldn't unlock the passenger side even by hand.
Once I disconnected the battery I could lock/unlock as I needed.

What could this be?
Car is a 2001 Mitsubishi Mirage FWD

 

[mk378]

Typically that sound is relays chattering and electronics not functioning properly because the system voltage is too low, that is the battery is practically dead.

 

[Audios]

Defienintly sounds like the modules are freaking out from low voltage. Definitely get a charger on it before starting. Im trying to sell an X3 thats been sitting for a few weeks, cranking it with the weak battery killed the Immoblilzer module, $500 later it starts again.....

 

[Spetz]

Thanks guys.

I will put the battery on charge.

However this was happening regardless of whether the key was in ignition or not, and the car did start. The noise continued while the car was running until I turned it off and then took the battery lead off again.

 

[kc8adu]

capacitors in the pcm.
pretty sure the issue ran up to 2003.
surprised it runs if thats it.
for a while i was getting several of those pcm's a week.
pop the cover and see if it smells fishy.

 

[Spetz]

Hi everyone,

A bit of an update, I located the fuse for "Door Lock ECU" and pulled that out.

Now there is no buzzing when I connect the battery to the car.

Is a door lock ECU just a relay?

 

[mk378]

Likely that means "Electronic Control Unit". It's not just a relay it does things like process the signal from the keyless remote.