hardware test at boot up

[testeng1966]

How do i get the Mac to run the hardware self tests. I saw the guy at the Genious Bar do it on my MacBook Pro.
I replaced the parts that showed bad, i would like to run it again.
I tried holding down the D on powerup but didn't work

 

[Eddyisgreat]

Apple Hardware Test: Insert the second grey "Applications Install" disk that was included with your machine, then hold down the D key.

But the test they run and the test "we" run are very different. The one they use is a bit more comprehensive, but you'll still be able to get something to work with if you have problems.