2008 LS460 with 90k miles. Recently I noticed when I am driving slowly (through the neighborhood for instance) and gently apply the brakes i get what sounds like a clicking/knocking sound. It seems like it’s from the front passenger side but I’m not 100%. The brakes work fine, not grabby, don’t pulse, no warning lights (which appears that it would exclude the actuator problem). Any other ideas?

Wheel bearings

you sure it is the passenger side? This is the same exact noise of the brake actuator but it is on the driver side, right in front of the firewall

The bakes can work just fine and there can still be noises coming from the actuator. Some people drive for years with the clicking and popping noises while others hear it and then very soon after the dash lights up with failing actuator codes. You say you hear it driving slowly. Try coming to a stop and let off the brake pedal fully and reapply it a few times. Don't slam on the pedal, just apply as you normally would. If you keep hearing a clicking, popping or slight groaning or "barking" as you apply force or while letting up on the pedal, its very likely coming from the actuator.

There are more threads than you're able to read on this site about the actuator, its symptoms and how long people have lived with it or when theirs was replaced.On the bright side, they are warrantied for 10 years from the first date of service but there are stipulations. One of them being there must be codes present relating to a failed actuator. There have been people that have had theirs replaced by the dealer for free after the initial new car warranty while within the 10 year enhanced warranty without codes being present but it is very rare that a dealer would do this. I don't know but I would assume that the car was purchased by those people new from that dealer for them to "bend the rules" to get Lexus to pony up for the parts and labor if the car wasn't throwing codes to back it up. Be aware, if you don't have any sort of warranty and take it in because its making noise and you have the dealer diagnose the issue, if there are no codes pointing to a failed or failing actuator, you are likely on the hook for the cost to diagnose it. At this point, they may try to get you to pay to bleed the brake system on top of the diagnostic charge. From reading several threads here, it usually has little or short lived success.

Please post back here and let us know what you find.

Well I brought the car to Lexus. They said the suspension was tight and they saw no issues with the brakes aside from a brake pad that has a little play in it. They said the pads are basically brand new so it would be a waste of money trying to replace them. I told them about my concerns and the 10 year warranty issue and what other people have dealt with, and they said that they would specifically mention on the report that there were no brake issues noticed and if it was missed that I had been within the 10 year period to get it fixed under warranty.

I’m not particularly happy with their response, but they spent an hour trying to locate the knocking sound and the brake pad having a little play in it was the only thing they could find. They said the vehicle is in excellent condition and I have nothing to be worried about. So I guess that’s the update whether we agree or not...

The fact that it only happens under very light braking makes me feel more comfortable with their explanation.