Your Dell might have diagnostic lights labeled A B C D on the rear that can help you diagnose problems with your Dell machine. Not all models will have these, but if your computer does, you can reference these and quickly repair a problem that might have taken you days to figure out. If your computer does not have lights, it will probably only issue a beep code, which is fine. However, the lights can confirm things a beep code cannot, such as no power to the system.
The image above shows a working Dell with all four lights green. If, however, you have anything different, you can look up your model on the Dell website for further documentation on these error codes. We will list a few of the most common here, but there are certainly more on the Dell website.
A B C D — No lights indicates the system is getting no power. You can confirm the outlet is working, but if you are still not getting power, you could have a problem with either the power supply, front switch or the motherboard itself.
A — If only the yellow ligth is lit, this means the computer is off and receiving power.
A B C – If A B and C are yellow, this means the BIOS is not running or not finishing (completing its POST).
B — If B is yellow, this means you are having some type of issue with the power supply.
C — If C is yellow, this means you have some type of problem with the motherboard.
A B D Yellow and C Green –This means you could have a problem with your CPU.
A B Yellow and C D Green — This means you have memory installed, but there is a problem with it.
These are the top diagnostic conditions that can prevent your system from booting. You may have different lights and still be able to boot, but a lot of those problem can be quickly fixed once you boot up the computer. One important thing you can try if you are receiving any of these critical conditions is to shut the system down, remove the plug and open the case. Make sure you touch a piece of metal on the case’s chassis to ground yourself, then proceed to making sure all cables and cards are secure. Be careful not to touch any chips on the memory or the motherboard in the process.
If you are still having problems with your Dell computer, be sure to contact us on our computer repair forums today!
dear sir
my problem ihave a pc dell but does not work there is a light yellow in it and A-B are yellow also so please i need help.thank you
well i saw the d was yellow and delayed going green. what does that mean? all the rest went straight to green and the pc doesn’t boot
If the other lights are yellow and the d is gree, this indicates a BIOS failure. Read more about that here: http://support.dell.com/support/edocs/systems/ws530/en/ug/html/2swprob.htm#1164104
added more memory to my computer and got a-c green /b-d yellow what could this be.
You should visit the Dell site and download the manual for your model. The manual should tell you all of the various codes.
I have a b c green d yellow….I have no clue what that means. i did as dell said and checked the wires and connections still no boot up. Anyone with any suggestions please let me know. It is a DELL Dimension 4600. Thank you for any responses
I would unplug any external devices and make sure there are no thumbdrives or disks in any of the drives. Is anything coming on the screen at all? I suggest you join our free forums so we can troubleshoot this more.
What if A, B, and C are green and D is yellow?
I would download the manual for your specific model from the Dell website.