User Guide

iMac (27-inch, Late 2009) — General Troubleshooting 23
2009-12-16
Diagnostic LEDs
The iMac (27-inch, Late 2009) computer has four built-in diagnostic LEDs on the main logic
board that can help you to troubleshoot the computer. The LEDs are located on the bottom left
edge of the logic board (under a piece of black mylar tape) and can only be seen when looking
through the lower vents of the enclosure. Refer to the next page for a close up graphic of the
troubleshooting LEDs.