I'm not sure I can tell you much about how to diagnose the problem. That's because I incorrectly thought the problem was with some other part of the suspension. After the third time I was sure I was right, too. Turns out I wasn't. Go figure....
All I can tell you is what my symptoms were.
- On slow speed turns, my suspension would creak, groan and squeak.
- Initially, at low speeds (5 to 10 mph) and when hitting a bump such as a speed bump, I could hear a fairly loud metallic "click" as the strut was compressed.
- later as time went by the noises (all of them) got louder and louder till I could hear the "click" at most speeds whenever I hit a sharp bump.
- the sound convinced me that the front end was going to drop out sometime (didn't of course nor would it have).
All I can say is take it to a dealer, tell him about the noise and ask him to check the struts. Be prepared, though, if you don't have an extended service plan, it wont be cheap.
Sorry, that's the best I can do.