Advanced Troubleshooting 37
Advanced Troubleshooting
Diagnostic Lights
  CAUTION: Before you begin any of the procedures in this section, follow the safety instructions 
located in the Product Information Guide.
To help you troubleshoot a problem, your computer has four lights labeled "A," "B," "C," and "D" on 
the back panel (see page 51). The lights can be yellow or green. When the computer starts 
normally, the lights flash. After the computer starts, all four lights display solid green. If the 
computer malfunctions, the color and sequence of the lights identify the problem.
Light Pattern Problem Description Suggested Resolution
The computer is in a normal off 
condition or a possible pre-BIOS failure 
has occurred.
Plug the computer into a working 
electrical outlet and press the power 
button.
ABCD
= yellow
= green
= off