Whining sound from engine bay

Ever since I installed all of my suspension stuff and the light bars, I have had this whining sound that i initially thought was coming from the speakers, but I've found out that it isn't so.

The sound doesn't sound like anything mechanical. My wheel bearings are brand new (toyota OEM wheel bearings; Less than 3k miles on them) along with all new spindles, seals, hubs. It has a "current" sound to it. Friend told me could be a bad ground with the lights and stuff, so i checked the ground. Good ground. So then I unhooked my circuit breaker, fuse panel, and relays for the switch setup. Still have the sound so its definitely not the electrical stuff.

I thought the sound was coming through the speaker so I unplugged the driver side speaker. No luck, sound is still there and sound pretty apparent that it's coming through the fire wall. Truck isn't showing any issues with charging or cranking (other than some slight drag but it has been below freezing here past couple of days). I'm assuming that the alternator is still charging since the truck is still running. The sound only happens when the speeds are above 35mph, and rpm doesn't seem to matter. The sound does get a little higher pitch when you get above 55mph but after that it pretty much stays the same. If you are below 35mph, it doesn't make sound.

I'm at my wits end trying to figure out what the damn noise is. I'm almost to the point that It's fixing to have to go to the dealer to be looked at. Anybody have any ideas on what I should check.

 

Ok so lets clarify what you are saying....

It makes a whining sound while driving down the road..higher pitch ( drive line ) at 55 mph and doesn't make a sound below 35mph?

 

Exactly. The whining sound never happens below 35mph. It also doesn't seem to be RPM specific. I can get a 3k RPM below 35mph and no noise or i can be at 1500 RPM at 40 mph and it's whining. The whine does seem to get to a higher pitch at around 55mph.

 

Check your front and rear axles differential oil levels and make sure they are at the proper levels. The oil should be close to running out of the fill hole.

 

Oil levels are all good. I checked front diff, rear diff and transfer case. Oil was just changed around 2k miles ago. Also have checked power steering fluid, brake fluid, coolant. I've greased all axles, upper control arms, leaf springs.

Like i said bearings are brand new. I replaced the entire spindle assembly on both sides. The only thing that was reused on the spindle was the dust shield. So all new ball joints. Only thing that I have seen that could be it would be something like the idler pulley but it never does it at idle, no matter how much you rev it. So that's got me at a loss.

I don't see the brakes making this kind sound.

 

So it is definitely a front end sound that is speed dependent and not a sound coming from the engine. I just want to eliminate the possibility of the sound coming from the engine.

 

I think that the sound is coming from the engine bay. I'm pretty sure that it's not a front end problem. It doesn't sound like anything mechanical.

 

Don't mean to sound like an ass, but have you considered it possibly being tire noise? If you recently put larger or even jut different tires on you may be hearing the noise of the tire on the road. Probably not what it is but just thought I'd suggest it because you never know!

 

Stuck in 4wd?

 

Thanks for all the opinions guys but I did finally get it figured out.

I chased around electrical problems, possible engine sounds, drive train sounds only to find out it was the damn light bar on my roof. The light bar was making a "harmonic vibration" noise kinda like a tuning fork. Ended up using some small clear vinyl tubing in between the fins and fixed the noise right up.

 

I've heard of this happening with roof mounted lightbars..

 

It's yer light bar
http://www.tacomaworld.com/forum/lighting/352236-how-fix-light-bar-whistle.html

 

Well you had me baffled.