Noise when applying brakes and turning steering column
The problem is probably linked to your power steering fluid pump, see if the fluid needs to be topped off (pretty simple) or bring it to a mechanic and have them look at the power steering pump.
I'm not sure if you're describing the same "noise" but my 02 has a creaking/popping/grinding noise when I come to a stop and turn the steering at the same time. For example when I pull a hard left, or right, into a parking space.. as I'm turning and coming to a stop, it makes a terrible creaking noise in the front end. There are multiple posts on this if you look at clublexus.com or lexusownersclub.com. It seems to be a prominent issue and something that no one seems to be able to figure out. Go figure, I think I've shopped my GS 10 times, for small stuff-mostly annoyances, where no mechanic was ever able to duplicate or find the problem. Oh well, small stuff nonetheless. Still love my GS.. my third and I'll probably up to the 430 next.
I just changed the lower arm ball bearing joint when i got the same sound and it stopped. At first my mechanic thought it was the lower arm. but it was the joint bearing
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