Q: What does four flashes mean? MBP won't boot

I own a macbook pro 15" from 2007 that spontaneously stopped booting. When I power it on it makes the usual pre-boot cd-drive noise but the screen never turns on. Instead the light on the front starts flashing four times.

Apple has surprisingly little literature on these flashing lights (known as POST codes) and I have no clue what to do now. All that I have found is on these four pages: http://support.apple.com/kb/HT2341 http://support.apple.com/kb/HT2538 http://support.apple.com/kb/HT1547 http://support.apple.com/kb/HT2130

This laptop is my entire life and I really need to bring it back to life. Is there any hope?

MacBook Pro, OS X Mountain Lion (10.8.4)

Posted on Jun 26, 2013 8:46 PM

I have this question too

Q: What does four flashes mean? MBP won't boot

All replies

Helpful answers

by Grant Bennet-Alder,

Grant Bennet-Alder Jun 26, 2013 8:51 PM in response to ItsAGoodDay
Level 9 (61,190 points)

Desktops

Jun 26, 2013 8:51 PM in response to ItsAGoodDay

That is a RAM problem:

the iMac in this article uses beeps, perhaps because its power light cannot be easily seen. The meaning is the same -- not enough working RAM to start up.

iMac (Mid 2007) and later models: About startup tones
Reply options

Link to this post

by ItsAGoodDay,

ItsAGoodDay Jun 26, 2013 9:13 PM in response to Grant Bennet-Alder
Level 1 (0 points)

Jun 26, 2013 9:13 PM in response to Grant Bennet-Alder

Even though I did not modify the RAM in any way? Can RAM malfunction like that? It seems odd that both sticks would go bad simultaneously.

How do you recommend testing to see if htis works?
Reply options

Link to this post

by Grant Bennet-Alder,

Grant Bennet-Alder Jun 26, 2013 9:19 PM in response to ItsAGoodDay
Level 9 (61,190 points)

Desktops

Jun 26, 2013 9:19 PM in response to ItsAGoodDay

RAM does indeed fail like this.

It also could be that one failed yesterday and the other failed today. Or that your Mac uses paired RAM, and one has failed but neither can operate if both are present with one failed.

You could try it with one removed, then the other removed. This changes the RAM timing, so it may not fail this way. It also may not work at all this way.

If this is third-party RAM, it may be covered by a Vendor warranty, where they will exchange it.

Were you considering a memory upgrade? Now is the time.
Reply options

Link to this post

Q: What does four flashes mean? MBP won't boot

All replies Helpful answers

by Grant Bennet-Alder,

iMac (Mid 2007) and later models: About startup tones

by ItsAGoodDay,

by Grant Bennet-Alder,

All replies

Helpful answers