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Advanced Troubleshooting  
Dell™Dimension™4600SeriesServiceManual 
Diagnostic Lights 
Beep Codes 
System Messages 
 
Diagnostic Lights 
To help you troubleshoot a problem, your computer is equipped with four lights on the back panel labeled "A," "B," "C," and "D." These lights can be yellow or 
green. When the computer starts normally, the lights flash. After the computer starts, the lights remain green. If the computer malfunctions, the color and 
sequence of the lights identify the problem. 
 
 
CAUTION: Before you begin any of the procedures in this section, follow the safety instructions in your Owner's Manual or Product Information 
Guide.
The computer is in a normal 
off condition or a possible 
pre-BIOS failure has 
occurred. 
Verify that the computer is plugged into a working electrical outlet and that you have pressed the power 
button. 
Memory modules are 
detected, but a memory 
failure has occurred. 
l If you have one memory module installed, reinstall it and restart the computer.  
l If you have two or more memory modules installed, remove the modules, reinstall one module, and 
then restart the computer. If the computer starts normally, reinstall an additional module. Continue 
until you have identified a faulty module or reinstalled all modules without error.  
l If available, install properly working memory of the same type into your computer.  
l If the problem persists, see "Contacting Dell" in your Owner's Manual for instructions on obtaining 
technical assistance.  
A possible expansion card 
failure has occurred. 
1. Determine if a conflict exists by removing a card (not the video card) and then restarting the 
computer.  
2. If the problem persists, reinstall the card that you removed, remove a different card, and then 
restart the computer.  
3. Repeat this process for each card. If the computer starts normally, troubleshoot the last card 
removed from the computer for resource conflicts (see "Resolving Software and Hardware 
Incompatibilities" in your Owner's Manual).  
4. If the problem persists, see "Contacting Dell" in your Owner's Manual for instructions on obtaining 
technical assistance.  
A possible video card failure 
has occurred. 
l If the computer has a video card, remove the card and reinstall it, and restart the computer.  
l If the problem still exists, install a video card that you know works and restart the computer.  
l If the problem persists or the computer has integrated video, see "Contacting Dell" in your Owner's 
Manual for instructions on obtaining technical assistance.  
A possible floppy or hard 
drive failure has occurred. 
Reseat all power and data cables and restart the computer. 
A possible USB failure has 
occurred. 
Reinstall all USB devices, check cable connections, and then restart the computer. 
No memory modules are 
detected. 
l Reinstall all memory modules and restart the computer.  
l To eliminate the possibility of a faulty memory connector, remove all memory modules, reinstall one 
memory module at a time (if the computer supports a single module), and then restart the 
computer. If the computer starts normally, move the memory module to a different connector and 
restart the computer. Continue until you have identified a faulty connector or reinstalled all modules 
without error.  
Memory modules are 
detected, but a memory 
l Ensure that there are no special memory module/memory connector placement requirements.  
l Verify that the memory modules that you are installing are compatible with your computer.