For 2+ years now, the light on my MacBook Pro (Santa Rosa 2.2 ghz) charger would intermittently go out. When the battery was low and the charger was charging the battery, the light would glow amber as it is supposed to. Charging worked fine. When the battery was fully charged the light would change to green as normal. But then, inexplicably, if I left it plugged in (which I usually do) the charger light would go out. If I unplugged and then replugged it, it would change to green. And then, after a while, it would go out again. I read about the charger lights and was told this was definitely abnormal, it should be either green or amber, never off. I tried various fixes including resetting the PMU. But no luck. So, 2 years ago, I went to an Apple store and they replaced the power adapter under warranty. No change in the situation. When my video card failed a few months ago and they changed the motherboard (again under warranty) I hoped that the charger light issue might also be cured. No luck, same problem continued. But since the charger was operating normally despite the light going out, I just lived with it. But now I am planning to upgrade to a new computer and sell this MacBook Pro. So I am eager to give it a clean bill of health and I undertook once again to figure out if there was a problem with the charger or charging system. I googled and found this article which apparently hadn't come up in my prior searches: http://www.webomatica.com/wordpress/2007/01/02/macbook-magsafe-not-charging/ -------------- excerpt: (credit to generaladam): 01/17/2007 at 10:18 am Good News, it turns out I didn’t have to go to the apple shop at all, heres what worked for me atleast. Try putting the Mac OS CD 1 in and rebooting your computer, while its starting up, (after the sound) press D, and it will run a hardware diagnostic test which seems to have magically solved the problem of the adapter, good luck. --------------- So I ran the hardware diagnostic test on the original OS restore DVD, the "extended test" and although it reported no problem found, I was happily surprised that it worked: the charger light now stays green when the battery is charged. I am happy to have found an easy solution and wanted to share it with others out there who have had the same pesky problem.