@vinylcake from the service manual for your computer: · LED 1 and LED 2 Blinking Power Button Amber · Problem Description A possible system board failure has occurred. · Troubleshooting Steps · • Disconnect all internal and external peripherals, and re-start the computer. If the computer boots, add the · peripheral cards back one by one until you find the bad one. · • If the problem persists, the system board is faulty. · LED 1 and LED 2 Blinking Power Button OFF · You do want to make sure that you properly inserted all your cards and that everything is connected. Since you did not tell us to what extend you cleaned your computer and exactly what you did, it will be difficult to pinpoint this. Answer from oldturkey03 on ifixit.com
Dell
dell.com › support › kbdoc › en-us › 000126021 › a-reference-guide-to-the-dell-optiplex-diagnostic-indicators
A Reference Guide to the Dell OptiPlex Diagnostic Indicators | Dell US
With this series, the diagnostic LEDs changed to include a combination of the Power button LED state and the diagnostic LED indicators. The Diagnostic LEDs remain 1, 2, 3, 4, and placed on the front of the unit.
Dell
dell.com › dell community › desktops › optiplex desktops
Optiplex 960 MT blank screen...Diagostic LEDS= 1 2 3 and two beeps | DELL Technologies
December 8, 2022 - 1,2,3 with an amber power light is a failed CMOS battery, That would be a CR2032 which can be bought at a dollar store and is very inexpensive. 1,2,3 with a normal blue power light could mean that the boot sequence is incorrect and the system ...
diagnostic lights 1,2,4 are lighting what does this mean
I have an XPS 400 Windows XP Intel Pentium D CPU 2.80 GHz 1024 MB memory Radeon X300 SE 128 MB Hypermemory The problem is the fan is constantly running and loudly, the front diagnosti... More on dell.com
6
0
March 13, 2008Diagnostic leds 1 2 4 and then 3 --- front power button failure ?!?
On a Dell OptiPlex 790 the diagnostic leds 1 2 4 turned on, followed by led 3 only (while the power button was solid blue). Looking into the user manual, there is no such pattern or sequence of patterns, however, there is a led 3 only explanation of "A possible system board failure has occurred" with no light ... More on dell.com
3
0
December 21, 2023Dell Precision T3500 Diagnostic Lights 123 and 2 short beeps
The same situation happened here. It worked, then I added a 2GB stick of RAM to the RAM I had. It showed me an error about changing memory configuration. I pressed continue, and it shut down. So, I pulled the extra stick out, and now when it's booting, it goes like 3, 4 then 1, 2, and then 1, 3, 4. More on reddit.com
3
3
July 13, 2023Dell optiplex 390 error lights 1 and 2
I upgraded my CPU in my Dell optiplex 390 to an i7 2600k and now its showing me orange lights 1 and 2 · Edit: it also gives me the same error when I put back the old CPU ... These are diagnostic LEDs and when pc do not post they give a clue what might be wrong. More on dell.com
2
0
December 13, 2022Videos
00:31
Dell Error Code 1 2 3 - YouTube
03:36
Dell Diagnostic Lights 1 and 3 on an Optiplex 790 Error Code Memory ...
02:59
What's REALLY Causing Your Dell LED Code 1 3 Error? Tutorial by ...
10:51
Dell Optiplex 380 – Only Lights 1, 3, 4 Are On? Here’s How to ...
06:15
FIXED! Dell Optiplex Amber Light Issue [English] - YouTube
11:59
Dell Optiplex 745 Error code 3, 4 repair - YouTube
Dell
dell.com › support › kbdoc › en-us › 000153002 › a-reference-guide-to-the-precision-workstation-diagnostic-indicators
A Reference Guide to the Precision Workstation Diagnostic Indicators | Dell US
With this series, the Diagnostic LEDs changed to include a combination of the Power button LED state and the diagnostic LED indicators. The Diagnostic LEDs remain 1, 2, 3, 4, and placed on the front of the unit.
Dell
dell.com › support › kbdoc › en-au › 000126021 › a-reference-guide-to-the-dell-optiplex-diagnostic-indicators
A Reference Guide to the Dell OptiPlex Diagnostic Indicators | Dell Australia
With this series, the diagnostic LEDs changed to include a combination of the Power button LED state and the diagnostic LED indicators. The Diagnostic LEDs remain 1, 2, 3, 4, and placed on the front of the unit.
Cohlife
cohlife.org › wp-content › uploads › A-reference-guide-to-the-Dell-OptiPlex-Diagnostic-Indicators-_-Dell-US.r.pdf pdf
A reference guide to the Dell OptiPlex Diagnostic Indicators
July 21, 2023 - The Diagnostic LEDs remain 1, 2, 3, 4, and placed on the front of the unit. You could · identify these computers by their flat black and gray front face. 🛈Note: If you have an OptiPlex All In One (AIO) Computer, use the reference tables below. 🛈Note: To see the contents of a section, ...
Iss
iss-kb.iss.k12.nc.us › books › windows-devices › page › dell-diagnostic-led-blink-codes
Dell Diagnostic LED Bl... | ISS Tech Knowledge Base
For instance, on laptops, battery codes for Low Battery or Battery Failure situations will not be displayed when Diagnostic Error Codes are being displayed. For diagnostics pattern 2-amber, 8-white connect an external monitor to isolate between system board or graphics controller failure.
Dell
dell.com › dell community › desktops › locked topics – desktops general
Dell diagnostic lights 1 & 2 staying lit / boot-up time has tripled / RAM tests OK | DELL Technologies
August 1, 2011 - I am using 2006 Dell XPS 400 / 2gb DDR2 SDRam / nvidia 9600GS / 20" Dell LCD Flat Panel / Win XP Media Center Edition Problem started 4 days ago When I start the PC the Diag. lights flash a few tim...
Dell
dell.com › home › support home › product support › manuals
Dell Precision Workstation T5610 Owner's Manual | Dell US
The most significant bit is labeled with the number 1, and the other three are labeled 2, 3, and 4, as you go down or across the LED stack. The normal operating condition after POST is for all four LEDs to be ON and then turn off as the BIOS hands control over to the operating system.
Dell
dell.com › dell community › desktops › locked topics – desktops general
diagnostic lights 1,2,4 are lighting what does this mean | DELL Technologies
March 13, 2008 - when the 1,2,4 lights are on means its in a power save mode called QRT mode it has to do with the vive setup do you have an owners manual it will explain better u can shut this off .here is a link to the pdf manual from the dell site it will ...
Gitral
gitral.fr › upload › userfiles › files › 64462538148.pdf pdf
Dell light codes optiplex
your computer has four lights labeled 1, 2, 3, and 4 on the front panel. Displays the results of the test and any error conditions encountered. Allow a minute for the power to drain. When the Dell Diagnostics Main Menu appears, select the test you want to run.
Dell
dell.com › dell community › desktops › optiplex desktops
Diagnostic leds 1 2 4 and then 3 ---> front power button failure ?!? | DELL Technologies
December 21, 2023 - On a Dell OptiPlex 790 the diagnostic leds 1 2 4 turned on, followed by led 3 only (while the power button was solid blue). Looking into the user manual, there is no such pattern or sequence of patterns, however, there is a led 3 only explanation of "A possible system board failure has occurred" with no light ...
JustAnswer
justanswer.com › computer › moage-power-button-2-3-buttons-blinking-dell-desktop.html
Expert Solutions for Dell Diagnostic Lights and Blinking Codes
Your Dell Precision T5500 desktop is displaying an amber power button along with blinking lights 2, 3, and 4. According to the Dell Community, these diagnostic lights signify "USB subsystem configuration activity in progress or USB subsystem failure...
Dell
dell.com › support › manuals › en-us › dell-pro-pc14250-laptop › dell-pro-14-pc14250-owners-manual › system-diagnostic-lights
Dell Pro 14 PC14250 Owner's Manual | Dell US
The diagnostic light codes consist of a two-digit number, and the digits are separated by a comma. The number stands for a blinking pattern; the first digit shows the number of blinks in amber color, and the second digit shows the number of blinks in white color.
Website Files
cdn.prod.website-files.com › 67239bb2f79469dfb676003e › 67380c013670d5a0526b3f91_23859521925.pdf pdf
Dell 790 diagnostic lights 1 2 3
optiplex 790 lights 1 and 3. Dell optiplex 790 diagnostic lights 1 2 3.
Reddit
reddit.com › r/dell › dell precision t3500 diagnostic lights 123 and 2 short beeps
r/Dell on Reddit: Dell Precision T3500 Diagnostic Lights 123 and 2 short beeps
July 13, 2023 -
Hi guysI was hoping to get some helpI got this Dell Precision T3500. which has been working pretty well for a long time, but recently it decided to act up and now it won't boot and it gives me the 123 diagnostic lights error and just before that (or about the same time) it beeps twice (short beeps)
the manual was checked: https://dl.dell.com/manuals/all-products/esuprt_desktop/esuprtl_precision_workstation/precision-t3500_service%20manual_en-us.pdf and it says that the error means : ´other failure´
there's nothing for the 2 short beeps in the manual.
someone actually paid for some diagnostics online but that resulted in no resolution, that was posted here: https://www.justanswer.com/computer/9pq0y-dell-precision-t5500-post-error-leds-1-2-lit-power.html
here are my 2 cents becuase I figure someone might run into this problem again and there's no actual resolution posted anywhere as far as I could tell.
my resolution:
In my case, I had 4 GB of memory total: 2 sticks of 2gb each... the people that sold me this machine which I'm using as a firewall for a school (seems like an overkill) put in 2 different sets of memory, in any case the comptuer did work ok for years.. memory was detected.. all was fine but it appears that one of the memory sticks is the one causing the issue.
Once I figure out which memory stick seems ok.. I put that as the only ram stick and now my pfsense firewall is back to live... tomorrow I'm buying 8gb of memory (2 sticks of 4gb) to replace both sticks.. hopefully this can help someone.
Top answer 1 of 2
1
The same situation happened here. It worked, then I added a 2GB stick of RAM to the RAM I had. It showed me an error about changing memory configuration. I pressed continue, and it shut down. So, I pulled the extra stick out, and now when it's booting, it goes like 3, 4 then 1, 2, and then 1, 3, 4.
2 of 2
1
Glad to hear you solved the problem. You did exactly what I would've recommended: pull out components one by one until you isolate the problem/faulty component. All hardware has a finite lifespan. It looks like your RAM stick has reached the end of its life.
Dell
dell.com › support › manuals › en-us › dell-pro-pc16250-laptop › dell-pro-16-pc16250-owners-manual › system-diagnostic-lights
Dell Pro 16 PC16250 Owner's Manual | Dell US
The diagnostic light codes consist of a two-digit number, and the digits are separated by a comma. The number stands for a blinking pattern; the first digit shows the number of blinks in amber color, and the second digit shows the number of blinks in white color.
Dell
dell.com › dell community › laptops › laptops wiki
Dell Diagnostic Light Patterns and Beep Codes: How to Identify and Fix Hardware Issues | DELL Technologies
September 15, 2025 - Here’s an example of a diagnostic light table, where 2 amber flashes followed by 3 white flashes indicate “No Memory/RAM detected”:
Reddit
reddit.com › r/optiplex › dell optiplex 390 diagnostic lights 1 and 2
r/optiplex on Reddit: Dell Optiplex 390 Diagnostic lights 1 and 2
May 31, 2023 - After reseating the ram and hard drive, attempting to boot results in a POST failure, the pc freezes while booting and the amber diagnostic lights 1 and 2 light up solid.
Dell
dell.com › dell community › desktops › optiplex desktops
Dell optiplex 390 error lights 1 and 2 | DELL Technologies
December 13, 2022 - I upgraded my CPU in my Dell optiplex 390 to an i7 2600k and now its showing me orange lights 1 and 2 · Edit: it also gives me the same error when I put back the old CPU ... These are diagnostic LEDs and when pc do not post they give a clue what might be wrong.