03 4runner buzzing noise at start up

[Oilfield Trash]

Recently my 03 4runner has a buzzing noise at startup, coming from the center dash area lasting about 20 seconds. I e done the searches and read all info on the secondary air pump issues. I have also read of the bypass for it but cannot find the parts for a 2003. 04 and up, yes. But not 03.

It is throwing no codes at all. My questions are: where can I find a bypass kit for this sai problem, if it is this problem. Second: should I look or trouble shoot more to see if anything else could be causing it.

It is a long distance commuter, daily driver. I drive 1000 to work every 2 weeks and 1000 miles back. I don't want to get stranded

 

[AuSeeker]

2003 and 2004 4Runners don't need the bypass they don't have the air pump only 2005 and onward, you have no worries!!

The buzzing sound you're hearing sounds normal as it's most likely the booster pump motor on the brake master cylinder, it should run for about 20 seconds on startup and then about every third time you depress the brake pedal to buildup pressure to give you power brakes.

How long have you own your 4Runner, V8 or V6?

 

[Bografan]

Another possibility? I have a 4th gen and am having the same issues. And after a lot of fiddling around, and a lot of reading, I found out that the AC blend motor is likely the culprit. (The buzzing seems to be coming from behind the Hazard light button on my 07's dash.) If it makes the noise more often in one A/C position than another, you may have the same issue. The fix, from what I have read so far, is a $60 Denso part and tearing apart the dash for fun evening.

 

[Oilfield Trash]

2003 and 2004 4Runners don't need the bypass they don't have the air pump only 2005 and onward, you have no worries!!

The buzzing sound you're hearing sounds normal as it's most likely the booster pump motor on the brake master cylinder, it should run for about 20 seconds on startup and then about every third time you depress the brake pedal to buildup pressure to give you power brakes.

How long have you own your 4Runner, V8 or V6?

I'm the 3rd owner, had it a few months. 162k miles. Guess I'm lucky if that's the only issue so far.

Are you saying it is supposed to do this? And depressing the pedal is doing what ? Yes. I am an idiot on mechanical issues.

 

[rich045]

Another possibility? I have a 4th gen and am having the same issues. And after a lot of fiddling around, and a lot of reading, I found out that the AC blend motor is likely the culprit. (The buzzing seems to be coming from behind the Hazard light button on my 07's dash.) If it makes the noise more often in one A/C position than another, you may have the same issue. The fix, from what I have read so far, is a $60 Denso part and tearing apart the dash for fun evening.

mine just started making that noise as well, so other than changing a denso part, what does it actually affect?

 

[AuSeeker]

I'm the 3rd owner, had it a few months. 162k miles. Guess I'm lucky if that's the only issue so far.

Are you saying it is supposed to do this? And depressing the pedal is doing what ? Yes. I am an idiot on mechanical issues.

Well if it is indeed the master cylinder booster pump you're hearing and not the AC blend motor as Bografan suggest, it's a normal sound.

On older vehicles to have power brakes they would have a big round vacuum booster behind the master cylinder to help apply the brakes when you depress the brake pedal the vacuum would "pull" on a rubber diaphragm that would push on the piston in the master cylinder to assist your foot in applying pressure to the brake wheel cylinders and calipers, but on many newer vehicles and on these 4Runners they have instead an electric motor to power a small hydraulic pump to help with the braking, when you turn on your ignition and or start the vehicle the electric motor comes on until the proper hydraulic pressure to assist in braking is achieved, in the 4Runners case about 20 seconds, when you depress the brake pedal that pressure drops as it assists the braking action, after 2 or 3 times depressing the brake pedal the pressure has dropped below the required pressure to assist and the electric motor will start again to build up the pressure again and will come on again when the pressure drops during braking action.

So that's why if you listen you will hear the motor come on about every 3rd time you depress the brake pedal.

That being said I'm not sure what you're hearing as I'm not there, it could very well be something else that should not be making a noise, but if after the 4Runner has been parked for a while or overnight and you just turn on the ignition on without turning it to the start position you will hear what is the brake pump motor come on which is located directly behind the instrument panel but on the other side of the firewall.


Edit: When I read and replied to your original post this morning I was about to leave for work and misinterpreted what you meant when you said center dash, I was thinking center of instrument panel/speedometer, so it very well could be a blend motor for your AC, but for sure you don't have to worry about the very expensive air pump that the "bypass kit" is for!!

 

[Oilfield Trash]

Took it to a former Toyota mechanic. Opinion is actuator on blower motor. Most expensive is labor to take dash apart.

 

[Monark]

Another possibility? I have a 4th gen and am having the same issues. And after a lot of fiddling around, and a lot of reading, I found out that the AC blend motor is likely the culprit. (The buzzing seems to be coming from behind the Hazard light button on my 07's dash.) If it makes the noise more often in one A/C position than another, you may have the same issue. The fix, from what I have read so far, is a $60 Denso part and tearing apart the dash for fun evening.

I just had this same issue. If your AC controls will send air from dash to floor to defrost, your Mode servo is OK. If you can't get warm to mix with cold air, your air mix servo is bad or stuck. This is the lower one & easier to get to but still a pain. I could only access two out of three mounting screws without removing the blower. I loosened these & used the warm cold control to exercise the servo. Mine was just stuck. No noise for two days now.

 

[Bografan]

mine just started making that noise as well, so other than changing a denso part, what does it actually affect?

Depending on what the A/C is set on when the buzzing is heard the most-- And if the buzzing goes away when it is set elsewhere-- It effects whether the a/c is going to come out of the front vents, front vents and footwell vents, defogger, etc. Mine make the most noise when set on the front vents, which sucks here in Houston (we need all the a/c we can get) ...so I need to put it on `blend' to make the noise stop, which reduces the perceived cooling by reducing the volume of air from the vents because it's split.

 

[rich045]

Depending on what the A/C is set on when the buzzing is heard the most-- And if the buzzing goes away when it is set elsewhere-- It effects whether the a/c is going to come out of the front vents, front vents and footwell vents, defogger, etc. Mine make the most noise when set on the front vents, which sucks here in Houston (we need all the a/c we can get) ...so I need to put it on `blend' to make the noise stop, which reduces the perceived cooling by reducing the volume of air from the vents because it's split.

I havent even noticed it lately, i'll check which settings i leave it on but so far the AC works fine (it just started getting warmer here in NYC)

 

[Captsolo]

Another possibility? I have a 4th gen and am having the same issues. And after a lot of fiddling around, and a lot of reading, I found out that the AC blend motor is likely the culprit. (The buzzing seems to be coming from behind the Hazard light button on my 07's dash.) If it makes the noise more often in one A/C position than another, you may have the same issue. The fix, from what I have read so far, is a $60 Denso part and tearing apart the dash for fun evening.

Oilfield Trash

UPDATE TODAY 10/20/2020 Toyota Servo motor: I got the 30 second buzz noise coming from the AC dash dial to go away. It was definitely coming on when you turned the key on to "on" and it came from the part of the AC dials on the dash - the one with the little light and the #3 round dial directing the air to different parts of your car. See the links below for what the part looks likes. There is a little motor that causes the buzz inside the Toyota Servo motor.

Just found this youtube for a Lexus Lexus servo motor air mix repair taken apart by froggy - YouTube

Toyota Servo motor problem. Car Air Conditioner Servo Motor Disassembly & Repair - YouTube

Oilfield Trash

I just experienced the exact same symptoms today as in your 2007. Bussing happens only at start up - lasts for 30 seconds. Goes away. Buzzing is right behind the hazard light but shutting it off does nothing. We are switching the position of the "vents" to see if it goes away, but so far nothing works.
Buzzing goes away after 30 seconds every time?

Do you happen to know the $60 Denso part #?

I have a bad evaporator core and will be replacing it soon. I can have the tech fix that buzz at the same time.

Evaporator went out last month and air and motor are all shut off.


I have a 2005 V6 4runner.

 

[benny_js]

I just bought a 2006 v6 and it does the same exact noise. What was the final solution after all?
Thank you.

 

[southern_runner]

I just bought a 2006 v6 and it does the same exact noise. What was the final solution after all?
Thank you.

There are a lot of questions about this issue. My 2003 SR5 has the same issue: when you turn the key to ignition, you get a buzzing noise from the right side of the dash that lasts maybe 20 seconds or so, then stops.

It's the AC Damper Motor. If you unplug the connector on top, it won't make the noise. It's a relatively cheap part, but a pain to get to. There are three screws holding it in, and one is pretty much impossible to remove without also removing the entire blower/filter assembly.

Getting to it is easy, just remove the panel above the glove box and then the glove box itself. There's also a Youtube video that shows where it is, but not how to remove it.

https://www.youtube.com/watch?v=kKOhDF-zG6A

0637008860 Toyota 4Runner AC Damper Motor ,