Electronic buzzing noise upon start up

[Billynath1988]

I've owned my truck for about 2 years now and until recently never heard this noise.

On a cold start up. After a night of sitting or so.. Upon start up there is an obvious loud electronic buzzing noise for approx 20 seconds.. Almost like a cellphone on vibrate sound. Then its gone for the entire day. Any clue what it is?

 

[2014 Warthog]

It's not the ABS charge up sound that for some reason has gotten especially loud? Maybe check your brake fluid level and the entire unit for looseness or something touching it that shouldn't or something.

 

[Billynath1988]

Checked fluid.. Everything around it looks normal and clean.. Problem is I can't make it happen everytime I start up only first start in morning...so its hard to pin point. There is no symptoms of any kind. I scanned it and saw nothing abnormal

 

[preacher35]

Check your fuel pump.

 

[Billynath1988]

Have 3/4 of a tank.. Fuel pump engages with key on engine off and if u listen u can hear it.. Sounds fine to me.. The noise really comes on about 3 seconds after the truck starts up.. Goes for about 15 to 20 seconds and stops

 

[ThirdDeviation]

Is it coming from the right hand side of the dash? Loud enough that it's almost hard to talk over? Does it stop when you change the vent settings from top vents to bottom or vice versa?

If so, I'm having the same problem and believe that it's related to the blower motor. Servos in the motor that handle vanes that direct the air are my suspected culprit, but I haven't pulled stuff apart to R&R.

So, maybe good news is that it's nothing critical to the operation/safety of your vehicle. Bad news is that it's behind the dash, which isn't really fun to work with.

 

[Billynath1988]

yes its definitely loud. And I think its coming from the dash area. To be honest it took my by surprise and I was more confused as to what made that sound to pin point where it came from. by the time i open my door and got out of the truck to see it stopped. But you might be right. whatever it is.. its some kind of electric motor engaging and disengaging. I changed settings on the vents and it all seemed to move around fine but I didnt try it when the noise occurred. If it happens again ill try it.

 

[preacher35]

Is it coming from the right hand side of the dash? Loud enough that it's almost hard to talk over? Does it stop when you change the vent settings from top vents to bottom or vice versa?

If so, I'm having the same problem and believe that it's related to the blower motor. Servos in the motor that handle vanes that direct the air are my suspected culprit, but I haven't pulled stuff apart to R&R.

So, maybe good news is that it's nothing critical to the operation/safety of your vehicle. Bad news is that it's behind the dash, which isn't really fun to work with.

If your blower motor is the issue, relax. The blower motor is indeed, behind the dash, but you do NOT have to remove the dash to get to it (as opposed to the evap core). The blower motor is completely accessible under the glove box for diagnosis/removal/repair/replacement.

 

[Billynath1988]

I tried all the settings on the blower motor and vent position settings. Seemed to work normal and quietly. I cannot recreate the sound.... it seems to only happen once a day for the past 3 days.. only on first start up after an overnight sit.

 

[preacher35]

I tried all the settings on the blower motor and vent position settings. Seemed to work normal and quietly. I cannot recreate the sound.... it seems to only happen once a day for the past 3 days.. only on first start up after an overnight sit.

I'm completely stumped... Maybe [MENTION=66389]BlackWorksInc[/MENTION] (Toyota tech) will see this and chime in. If he does not have insight, nobody will.

 

[BlackWorksInc]

With the key off, depress the brake pedal about 20~40 times, then start the vehicle and see if you hear the noise.

 

[preacher35]

With the key off, depress the brake pedal about 20~40 times, then start the vehicle and see if you hear the noise.

BWI, what are you thinking it is, that would require the brake pumped? I am asking out of complete and utter ignorance.

 

[BlackWorksInc]

BWI, what are you thinking it is, that would require the brake pumped? I am asking out of complete and utter ignorance.

The process I am asking the OP to perform is basically de-pressurizing the brake accumulator (the cylinder that is pressurized to provide braking assistance on our units.) This way when the OP turns his vehicle on, he will hear the accumulator pump kick on to re-pressurize the system (it should run for around 60~90ish seconds if I remember), this may or may not be the noise the OP is hearing. I just wanted the OP to try this so that they can more easily hear the brake system functioning and rule out whether or not that is where the noise is coming from.

After we determine IF the noise is in fact coming from there, we can maybe decide if the pump is getting noisier; or if the OP just happened to lock on to the noise one day after never really paying much attention to it.

Some mentions of what I am talking about appear in this thread and the linked thread in one of the comments:
http://www.toyota-4runner.org/4th-gen-t4rs/107245-inconsistent-brake-pedal-travel-2.html

 

[preacher35]

The process I am asking the OP to perform is basically de-pressurizing the brake accumulator (the cylinder that is pressurized to provide braking assistance on our units.) This way when the OP turns his vehicle on, he will hear the accumulator pump kick on to re-pressurize the system (it should run for around 60~90ish seconds if I remember), this may or may not be the noise the OP is hearing. I just wanted the OP to try this so that they can more easily hear the brake system functioning and rule out whether or not that is where the noise is coming from.

After we determine IF the noise is in fact coming from there, we can maybe decide if the pump is getting noisier; or if the OP just happened to lock on to the noise one day after never really paying much attention to it.

Some mentions of what I am talking about appear in this thread and the linked thread in one of the comments:
http://www.toyota-4runner.org/4th-gen-t4rs/107245-inconsistent-brake-pedal-travel-2.html

Spoken like a true doctor.

 

[Billynath1988]

Ok I did the brake pump procedure last night and it wasn't it. so this morning it happened again.. I was able to pop the hood in time. It seems to be actually be the emissions air pump kicking on. But why so loud? Of course my phone didn't boot up camera quick enough to record it. But almost 100% sure that's the location of the sound. And until this week I've never heard it before.

 

[Jeff.Denson]

I've been having this problem for the past few weeks aswell. I switched my vent setting. I've tried to look for the buzzing, and don't know how to fix it. I've planned on having my shop replace/fix it but if some one knows how to fix it that would be great and save me some money! Haha

 

[preacher35]

Ok I did the brake pump procedure last night and it wasn't it. so this morning it happened again.. I was able to pop the hood in time. It seems to be actually be the emissions air pump kicking on. But why so loud? Of course my phone didn't boot up camera quick enough to record it. But almost 100% sure that's the location of the sound. And until this week I've never heard it before.

Is that "emissions air pump" a state requirement of New York?

 

[Billynath1988]

Unfortunately I believe I do. Correct me if im wrong but i believe the function of the airpump is to inject fresh air into the cat to get it to heat up quicker and burn hotter/cleaner faster. That is all fine and great but why the hell is it suddenly so loud when noone ever hears theirs and I never heard mine before. IF in fact thats what im hearing.. here is a link to a video I took this morning. Its much louder in person but you will get the idea


https://www.dropbox.com/s/vggi1mrle95fl5a/2014-07-18 15.23.49.mp4

 

[preacher35]

Holy crap! That is loud!

 

[2014 Warthog]

Initially I was thinking maybe something got in there like a leaf or a fan blade got bent or something, but listening to it, Nope. It sounds exactly like a cheap shop vac.

Bearing going out on the motor?
Motor or housing mount going bad or broken and is allowing the entire thing to vibrate against something?

Shop vacs typically sound like that because the motors and fans are cheaply made and not individually balanced so they vibrate the entire canister making a crap ton of noise in the process...