Apple MacBook Pro 17-inch (original, Core 2 Duo, 2.4GHz, Late 2007 CTO, Early 2008, and Late 2008) User Manual

Page 169

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MacBook Pro 17-inch (original, Core 2 Duo, 2.4/2.6GHz, 2008) Troubleshooting — Hardware Symptom Charts

169

Power-On Self Test (POST) Error Codes

The computer automatically performs a power-on self test when it is turned on after being fully
shut down (not a restart). This section describes what to do if you hear beeps during startup.
When this occurs, the sleep LED will stay on, occasionally flashing.

MacBook Pro relies on a combination of tones and blinking sleep LEDs to display power-on self
test (POST) error codes.

If the computer detects no SDRAM (Synchronous Dynamic Random Access Memory—also
referred to as RAM), or the RAM installed does not meet the appropriate specifications, the screen
will remain black but the power LED on the front of the computer will blink once per second to
signal the error. This error condition may be due to physically damaged RAM, the incorrect type
of RAM, or not having any RAM installed.

Some RAM may appear to pass the power-on self test (POST) but still cannot be addressed by
the operating system. In this case, the computer will display a gray screen, sound three tones and
blink the power LED on the front of the computer three times, pause, and repeat the blinking
until the computer is turned off.

Related Knowledge Base articles:
303083: Intel-based Mac Power On Self Test RAM error codes
303363: Intel-based Mac: Startup sequence and error codes, symbols

Blue screen appears (a spinning disc cursor may also be visible), Prohibitory Sign

appears (a), Kernel Panic dialog box appears (b), or Gray screen during startup

Make sure all external devices are disconnected and any ExpressCard has been ejected. If the

1.

kernel panic goes away, troubleshoot the external device by reconnecting each device until
the panic occurs.

If there are two RAM cards installed in the expansion slots, remove the top card and restart.

2.

• If symptom repeats, replace bottom card with known-good RAM card.
• If symptom does not repeat, replace top RAM card with known-good RAM card and restart.

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