2000 Sienna Whirring Sound

My 2000 Sienna has a sound when I put it in the ON position also. I wouldn't call it a whirring sound but more like Whoomp sound. It's almost like a vacuum pump or something activating itself.

That sounds about right,.. thanks for checking through your own Sienna. I would say the sound is like a whoooooom.

So if your hearing it, it mightbe normal then,.. what do you think?

It's certainly a strange "normal" -- wouldn't you say?

I've had the van a year and a half and it hasn't had any problems. My only complaint is its bad gas mileage.

ABS does a self-check on key on. you can hear this on some cars, could just be that you didn't notice it for the first few weeks. T

It is difficult to identify a sound without actually hearing it, but if it lasts about 3 to 5 seconds, then you may be hearing the antilock brake (ABS) actuator and pump doing a self-check. When the ignition is turned on, it powers up and cycles, and during the first 10 feet or so of vehicle movement, the ABS computer is looking for equal signals from each of the wheel speed sensors. If one or more of the sensors does not give the same signal or no signal, then the ABS check light will come on.

If you want to confirm if you are hearing the ABS actuator, set the parking brake, open the hood, and being very careful to keep away from moving parts like belts and fans, put your hand on the ABS actuator while someone switches the ignition to the on position without starting the engine. You should be able to feel it vibrate a little. ABS actuator location varies from vehicle to vehicle, in Toyotas, it is usually a silver cube about 6 ~8 inches per side with a bunch of steel tubing sticking out. BTW, if you have traction control, the ABS actuator also controls that function as well.