no airport card installed, no airport card installed

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This may be a hardware or software issue, so first we are going to discard a software issue. To do it, first reset the SMC > http://support.apple.com/kb/HT3964 Do the same with the PRAM > http://support.apple.com/kb/HT1379

If it doesn't work, reinstall Mac OS X. Insert the Snow Leopard DVD, hold the C key while your Mac is starting and reinstall Mac OS X. Make a backup before reinstalling, although you won't lose anything.

If nothing works, it's a hardware issue. Take it to an Apple Store or reseller to get the AirPort card replaced

Apple Hardware Test isn't designed to detect AirPort problems, or at least, I haven't seen any case where Apple Hardware Test has detected an AirPort issue.

You can do the SMC reset yourself, but if you want to take it to an Apple Store, good luck

I had this problem and I got it fixed. Go to about my mac and find out your air port card. It should be airport extreme. If it isn't go to your nearest apple store or anywhere that fixes apple computers and get it replaced to airport extreme

If it is still go and get it replaced.

I already knew that code, but I have never seen that code in Apple Hardware Test. Moreover, I tell to some users that Apple Hardware Test doesn't diagnose some parts because it never shows problems with them, and one of those is the AirPort card

> (optionkey) System Info>Network>WIFI

It looks to me like you are there, and no card recognized.

You do not say what MacBookPro you are running, check the DIY to see if you can easily access the card and reseat it.

> optionkey System Info>Network>WIFI

is your card being recognized by the system, if not possibly a loose connection.

AHT is capabable of detect WIFI card problems:

error code output component list: 4AIR: AirPort wireless card / W: Airport Wi-Fi card

Thanks mende1 - I see your point.

DIY= Do it yourself

http://www.ifixit.com/