Toot-toot: Diagnosing noise / whistle / tone

Well I hate to post this, but I've about worn out the search engine here looking for answers... Guess I'll just throw out some facts and thoughts and see if anyone has anything else to offer.

The truck: 2011 DC 4x4 SR5, 7,200 miles, Eibach coils, 5100s at 0, TSB springs. No problems with this set up since March.

Only recent addition: ARB bumper last week - no clue if it's in any way related.

So the past couple of days, I've noticed a steady, low whistling or humming noise. More accurately, it would probably be best described as a harmonic tone of some sort - kinda like you're blowing on an old glass coke bottle. It's not super loud, but it's audible enough that it's bugging my half-deaf ass.

During regular city driving, it starts up around 35-40mph and remains constant up to around 60 or so (my normal top speed on my commute). I took it up to 70 a little while ago, but I think the road noise simply overcame the mystery noise. If I stay at a steady 30 or so, I can get the noise, as well. Either way, the noise remains pretty constant until I get below 30 or so as I'm coming to a stop. There's no noticable vibration associated with this tone.

Now initially, I thought the sound was for sure coming from the front passenger side, but after some poking and prodding today, I'm not so sure.

I've pushed on windows and pulled on doors with no change. This is actually where I changed my mind about where it was coming from - when I'd lean over to the passenger side to tug on the door or push on a window, the sound seemed to migrate to a more ambiguious location somewhere toward the front of the truck.

So ruling some other things out...
- Braking - doesn't change anything
- Speed - doesn't change anything
- Let up on the gas - no change
- Lay in to the gas - no change
- Change gears - no change
- 4h - no change
- I've experienced the cross-wind windshield buzz. This isn't it.
- Windows up, windows down, it's still there
- Haven't done any off-roading aside from a dirt road or two

I thought maybe the wind was playing the jugs with the new ARB bumper, so I taped over some open areas around the signals as well as the open ends of the hoops which protrude to the interior of the bumper. No change.

When installing the ARB, I had to flip up and zip-tie the front fender liners. Dunno if this might be the cause. I haven't messed with them so far.

When I got home a while ago after a little troubleshooting drive, I popped the hood and listened to the engine. It actually sounds like I can hear a very similar tone in the engine at idle up under the engine cover. Maybe something to do with the air box, so I'll look at that.

Things I haven't messed with yet:
- Drivetrain stuff - axles, spindles, control arms, driveshafts, u-joints, etc
- Air intake stuff - air box, filter, etc
- ???

If I can't figure it out, I'll take it to the dealer, but for now, I'd like to at least make an attempt to stay as far away from there as I can.

Any suggestions?

I'm really hoping this doesn't get into bearing/differential territory at my mileage...

 

I'm getting some strange whining/whistle/humming/out-of-tune harmonica noise in my new Taco as well. First truck, total noob, only got 200 miles and love it but drove about 40 miles away on the highway and starting hearing the noise coming from the center/passenger side dash when I hit 70-80 mph. There may have been some gusty winds as well. It's loud enough to interrupt the JBL sound in a very annoying way. I've read it may be a bad windshield molding or leaf in the intake but haven't been able to verify this yet.

One thing I did notice is that the front license plate has the dealer plastic plate in it and I'm thinking this could be the cause. It is normally flattened in place but after the long drive I noticed the bottom was bent inward and could easily cause a vibrating sound. I've taken it off and will do a test to see if it resolves the issue but not sure I'll know unless there's some wind on the road as well. Maybe this is causing your issue as well?

 

Went out for another drive. Taped up all the holes in the bumper, taped up all around the windshield... No change. Checked the air filter... Looked okay. Ran down the road with the filter out and still had the noise. Rode the brakes a little with no change in noise. Jerked the wheel back and forth a little bit like a drunken monkey with no change. If I'm accelerating from a stop, and my target speed is 45-50, the noise pops up like clockwork right around the 40mph mark. If I'm just cruising at around 30-35, it just kinda gradually shows up.

The more I twist and contort like some retarded acrobat while driving, the more it seems the noise might actually coming from under the cabin on back toward the rear axle. Hope this isn't rear diff noise I'm hearing...

 

wow! just noticed mine today at 60mph. Right front passenger side. Subscribing

 

God damn , I have the same harmonic tone , but it only occurs when I turn sharply .

So faint you can almost not hear it , but it sounds like an electronic pulse

It sounds like it is coming from under the dash .

 

There is a chance it could be a wheel bearing. Check the right hand side bearings.

 

I have it to at 90 it is very loud

 

Just started hearing something similar on mine... Heard it before reading this thread.

 

Well, just a few days after posting this, I raised the front & rear, and I'm no longer noticing this noise. It may very well still be there, but I've got all the other noises & vibes associated with lifting to contend with, now.

 

I have an '06 prerunner with 128K mile and I have a similar noise popped up about 5k miles ago. It's driving me crazy. I just had a new set of tires put on thinking I may have developed a strange wear pattern or something. The noise is still there. I've checked all of my glass & door fittings for air leaks. Don't notice any. Starts at about 35-40 mph. It's like a whine or whistle with a very faint vibration in it. It's hard to tell where it was coming from.