Home Forums Hardware Mac Desktops & Notebooks LED light on MagSafe adapter

I wonder if somebody has a similar problem. MacBook pro 2008 (15", 2.2 GHz, 2 GB RAM) has the Magsafe adapter light off when fully charged. When disconnected-reconnected, it starts glowing green again.

History: about 6 months ago, the screen wiring and video card were replaced by Apple. The battery was replaced a long time ago. Symptoms after card replacement (not necessarily related to it) included spontaneous wake from sleep when the lid was closed, although the "wake from sleep at Ethernet activity" was disabled. In the Apple store they reset the power management unit and the unwanted wake up stopped. The computer is always plugged into the wall outlet when at home but travels often during the day and is on battery power then.

Two other laptops (2007 and 2009) always have the adapter green light on when the battery is fully charged. The "abnormal" one now has a replacement adapter plugged in and for several days the light was on when charged. Today it turned off again. Apple does not list that option and only vaguely states that when fully charged, the adapter light is green. Anything to do with the power port contacts? If yes, how can one diagnose or repair it? Will Apple hardware test do it? Or is this within normal behavior? Also, I am not sure whether this is serious or not since the battery charges...
I did not find any answers on the web, so I am posting it here.
Thanks for any help.

On my MacBook Air when the battery is fully charged the light on the magsafe is green. That is not something you are likely to be able to diagnose with software. I suggest a visit to the nearest Genius Desk.

Thanks! Thought so too... Could be the port.

You can check out the magport and magsafe visually. Check the pins, exercise them with a toothpick. Clean both with a qtip with some alcohol on it. (don't flood the port)

If the computer still shows ac power or charge up in the menubar, ignore the light. Those lights seem to go dim or out completely after awhile. The one here on this macbook is totally out, but works normally.

Thanks! Will try to clean up the port. FYI, the light is bright, is just off when fully charged.

there are two lights in the port. There is no such thing as an orange LED. But there are red and green, and at the right intensities the two mix to make the orange you see for charging. (though I've seen a couple magsafes with just a RED light, looks kinda evil)

If the magsafe is working normally, the lights really aren't that important. There's nothing you can do to fix them, short of replace the magsafe pack.

Interesting about the lights. Concerning your last suggestion, I got a replacement and the light goes off again. I am still thinking it is the port contacts; if the adapter is unplugged from the port and immediately replugged the green light comes back.

Have you tried Resetting the SMC and how long has it been since you Calibrated the Battery on your MacBook. It occurs to me that either or both of those might solve the problem.

Count the pins on the connector. 5 right? actually, there's only 3.

the connector can be plugged in one of two ways, so the outer two pins are the same, and so are the next set in. They are the power pins. The center pin is a communications pin.

When you plug in the pack to the computer, there are FOUR separate entities trying to establish communications.

The pack, it's quite intelligent actually. It won't provide power through the cord until it has the good word.

The magsafe end. Surprising amount of electronics in that little guy, a lot more than to just run the lights.

The magport on the computer isn't too bright but does participate.

And the computer.

All four of these need to have clear communications, and negotiate before the pack will start supplying power. If there's a problem, no power. You may have seen pictures of where people have abused their magsafe connectors and melted them, but you'll notice, no fires. Power is shut down immediately if there's a problem.

Anyway, so if there's a problem with the pins on the magport, it won't charge. Odds are good it won't even be recognized by the computer, but I've seen many examples of liquid spills that caused the pack to be seen but refuse to send juice.

Interestingly, the cable from the pack to the magsafe jack has only two lines. An outer shield that acts as one power line, and an inner power line. There's no communications line. The pack talks with the magsafe jack over the power line.

Thanks. The SMC (I incorrectly named it power management unit in the OP) was reset in the Apple store and apparently took care of the sleep wake problem.
Will try to calibrate the battery (it has not been done for a while).