2000 Dakota, this is on the right side, under the hood, near the fuse box. Not sure what it is as I am enginely challenged. It just started making noise, like it won't shut off (though it was previously not making sound). I can hear it from the inside of the truck, even after I turn off the key. I disconnect the battery terminal and it shuts off.

Can anyone tell me what it is? Thanks! Just wondering what it's going to cost me.

I did do the key code check and it says P done. One thing to note, the Air Bag and Brake lights on the dash now stay on, they didn't before this thing started growling.

 

My guess it looks like it part of the brake system so probably the ABS system.

I will move this to the 2nd generation Dakota sub-section.

 

Welcome to the forum Jedi.

You have 4 wheel ABS. It is likely the pump motor you hear running. The CAB (Controller, Anti-Lock Brake) has likely failed and is running the pump constantly (relay failed, it's somewhat common). It can be rebuilt or you can get a rebuilt unit.

It shouldn't affect the air bag light though.

 

could be a bad relay I had one buzzing under the hood too. replaced it and now it works fine. the relay was just sticking try tapping on it with a plyers.

 

Check GROUNDS, weird **** always happens when grounds are loose rusted or dirty, just go through and remove clean and re fasten everything, starting with the battery so you dont kill yourself. if nothing else it will give your computer a solid reboot and allow the problem to to restart itself and maybe give clues as to what or where the problem can be located.