I have a 2000 lexus gs400 and i have a irritating loud beepimg come from the dash when i crank thr car up an sumtimes while driving ,and when i hit thr brakes sumtimes it make it go off and it will be for alittle while and then go off,what do i need to do?

 

Do you have the ABS light on? When the ABS module is not working correctly there is a constant beeping when the car is on

 

Did you change your pads recently. Check your fluids, check your bleeding... and check the search function.

 

 

This may sound crazy but is the car equipped with a radar detector? i bought a used car one time and it had a detector hiding under the dash and it would just randomly beep while i was driving. I finally realized what it was when I did some investigation under the dash. Just a thought

 

This thread is useless without audio of the "beeping."

 

LoL naw... its quite clear what it is.

 

I have the same issue going on.... but more of a buzzing sound behind the drivers side lower dash (IMO) and intermittent off and all. Does not matter if I have HVAC on, or driving or idle, brakes engaged or not.... any help? No lights on dash at all.

 

Yes, I also have the intermittent buzzing (loud) which I think we have agreed is a servo motor going bad.

 

Signs point to your drivers side servo. Fortunately it's the easiest one to get to. I changed mine and it took about an hour.

https://www.clublexus.com/forums/gs-...vo-motors.html

OP mentioned the sound occurring while applying the brakes and that points to the brake booster.