Buzzer sounding from fusebox under the hood

When I got home last night and stopped the truck, a 2008 Tacoma TRD automatic, I heard a buzzing noise coming from the engine area. As far as I can tell it was coming from the fusebox. I'm not sure if this was the case I will look into it further and see if I can recreate it today. Can it be a relay? I think it was making the sound while the radiator fan was on but I'm not sure. Is this a thing? I've only had the truck for a week, this is the firsts time I've noticed this. Is it even possible or am I hallucinating?

 

Yes it could and probably is a relay.
Radiator fan is not electric and has no relay or wires going to it, unless it is an aftermarket installation.

 

Thanks yes i just saw the fan is on a pulley
I swapped out the relay with an identical one and the they only buzz on that position so the relays seem ok
Any idea what could be making them behave this way?
Its the relay on the right on the top position above the purple one.
The other relay below the purple one is identical and it also buzzes, but only when installed in the top position.
Is there a chart that maps out the relays and what they are used for?
Ive removed the relay for now, but it would be great to know what it controls. So far everything Ive tried seems to be working.

 

Chances are the chart is on the inside of fuse box cover.

 

thanks it looks to be the high/low headlight relay

 

Relays will chatter (buzz) when voltage is just low enough to de-energize the relay and then the voltage rises enough to activate the relay and so on. This happens very fast. So the relay is activating and deactivating many times a second causing a buzzing sound.

Check/replace the relay and check all wiring and connections in this circuit including bulbs.

 

Does the headlights flicker when it is buzzing?
Does it only buzz in one position (High or Low)?
Clean the relay contacts.

Check voltage on the relay coil wire Terminal 1 on the relay. It should be 12 volts in one position and 12 VDC in the other position.
Check the ground on terminal 2 of the relay, should read zero Ohms between the terminal and the negative terminal of the battery.

 

These can be invaluable for issues you're describing. Just a FYI if you didn't already know.

 

Thanks yes... I came close to buying a set a couple weeks ago but I held myself back I have so many things I cant keep track anymore

The relay buzz was pretty obvious I could feel it when i put my finger on it.

A stethoscope definitely has its place as a tool

 

Does the DIM Relay still buzz with the HEAD relay removed?

 

I will update soon... I swapped relays and the buzzing sound is induced on that circuit the high low headlight spot... I did believe i had my high beams on when it started buzzing but at the time i didnt know the relay was for the lights. I will look into it but so far it looks like a bulb problem or something with the high beam circuit.

 

The headlight relay is buzzing when the high beam switch is engaged, but only when the headlights are off. No issue when the headlights are on.

One thing to note is it's a US car and I'm in Canada. US cars don't have daytime running lights and since it's required for cars here so it had to be modified in some way.

Strange but thats when the buzzing occurs.

 

Are they using the headlights for DRLs or the front turn signals as is standard for most Tacomas?

 

Here in Canada headlights are required

 

I'd want to see what they modified then because stock Tacoma DRLs use the amber front turn signals not the headlights.

 

I will get to the bottom of it eventually... hopefully. Its not a priority at the moment... just more annoying than anything else.
Hopefully nothing is getting damaged... the relay does seem to be getting feedback somehow is my guess so I try and avoid inducing it.

 

Relays are pristine and the contacts looks as new when removed.

I havent noticed any flicker.

I will check the voltages on the relay... I assume I can just install with the cover off to check those voltages and resistance?

 

As for the contacts I was referring to the terminals where the relay plugs in to the fuse panel.

 

Which is the DIM relay?

Ive tried 2 relays and they only buzz when installed in the high/low headlight spot in the fusebox

 

It's labeled DIM on my 14.