when i start my truck, (which starts fine) and its running for 3-5 seconds, i get a light noise, which sounds like its comming from the drivers side dash, or drivers side firewall engine or dash ,

it lasts about 30 seconds then i put it in reverse and it still light noise coming, then i put it in drive and its fine.

note the ac/heat are off and its before i turn my hids on,

any help is better than nothing, thank you in advanced

 

Is it possible its the secondary air pump running. It runs for a short time after start up. Its located down by the bottom of the radiator a little closer towards the passenger side than center. It is normal. "A light noise" doesn't give me much to go on. Can you give a better description
Of the noise.

 

im trying to give a better description but its hard to describe lol. it did it 5 seconds after i started, and everytime i was at a light, and seemed to stop when the engine was up to normal operating temp, then i was at a light and it didnt sound.
i started it after work today, no noise. i was gonna record the noise but naturally it didnt wanna sound lol.

if i had to take a guess, it sounds like something from the drivers side dash area, i checked both speaker grills and all vents including defrost and they were secured. i dont think its anything serious, but who knows. we can also rule out hid ballast because it did it before they were turned on.