Random Sound, Does yours do this??? Please give this a look...

[MMTasty]

I did a lot of searching and couldn't find anything like this. I just bought an '01 with 120K SR5, Auto, V6... It's making this odd sound.

Here's a description:
fairly quiet, but audible
robotic/electronic sound of a buzz/humming
consistently 3-4 seconds, every few minutes
isn't speed induced, although, it may go away at high speeds and I just can't hear it
does it in 2 or 4wd
sounds like it's coming from under the truck
it's a similar sound to what I've heard some other make/model push-button 4WD vehicles make when you shift from 2 into 4WD

Anyone have any ideas? It's pretty cold here in Colorado if that means anything. It makes the noise EVERY time I drive it, every couple of minutes, and it's always the exact same length of time.

Thanks!

 

[BrianSD_42]

record a video with sound

 

[shootmymime]

I know 96 had a problem with charcoal canisters humming after being turned off. That's a buzzing noise. But not sure what it could be while running.

 

[SST221]

Most likely its the pump for the hydraulic brake booster. Late model 3rd gen's like your 01 and my 02 have a hydraulic braking system that works in conjunction with the traction control system. After you use your brakes a few times the pressure in the system drop's and needs to be replenished. The sound your hearing is the first the relay click then the pump runs for a few seconds to rebuild the pressure. In neutral with the truck running, step on the brake pedal three or four times is a row, you will then here the relay and then the pump running, once it stops hit them again 3 or 4 times and it will cycle again. It needs this type of system for TRAC to apply the brakes to the individual wheel without any input from the driver.

 

[MattAK]

I've also wondered what that sound was in my '01. Thanks SST221.

Most likely its the pump for the hydraulic brake booster. Late model 3rd gen's like your 01 and my 02 have a hydraulic braking system that works in conjunction with the traction control system. After you use your brakes a few times the pressure in the system drop's and needs to be replenished. The sound your hearing is the first the relay click then the pump runs for a few seconds to rebuild the pressure. In neutral with the truck running, step on the brake pedal three or four times is a row, you will then here the relay and then the pump running, once it stops hit them again 3 or 4 times and it will cycle again. It needs this type of system for TRAC to apply the brakes to the individual wheel without any input from the driver.

 

[MMTasty]

Most likely its the pump for the hydraulic brake booster. Late model 3rd gen's like your 01 and my 02 have a hydraulic braking system that works in conjunction with the traction control system. After you use your brakes a few times the pressure in the system drop's and needs to be replenished. The sound your hearing is the first the relay click then the pump runs for a few seconds to rebuild the pressure. In neutral with the truck running, step on the brake pedal three or four times is a row, you will then here the relay and then the pump running, once it stops hit them again 3 or 4 times and it will cycle again. It needs this type of system for TRAC to apply the brakes to the individual wheel without any input from the driver.

Actually, I think you're right. I noticed today that it's ONLY while I'm stopping or have my foot on the brake, and only after a few stops. I can feel a slight vibration though the pedal too. I took a video, but I'm not going to upload it if other ppl are hearing this too. I had a '00 that didn't do this, so I was worried. Thank you very much for the reply!!!

Now to wire in a switch to turn off the VSC so it doesn't cut power when I'm trying to pull out into traffic. I live in Steamboat CO, so I drive on packed snow/ice for months of the year...

 

[SST221]

:hatsoff: glad to help

 

[Evilmunkey]

My 02 does that it's the ABS pump cycling after so many times of depressing the brake pedal.