HP G62-a34SO Notebook PC support
Blank screen LED error codes
This document pertains to HP Notebook PCs with the HP Unified Extensible Firmware Interface (UEFI) beginning in late 2008.
Learn how to identify hardware problems using LED light codes.
When starting up your notebook, you might see a blank screen. If the diagnostic utilities detect a specific problem with hardware components, the fan turns on, but the screen remains blank. To help identify the cause of the problem, various LED lights on the keyboard blink a series of codes.
NOTE:The appearance and location of LED lights may vary between different notebook models. Check the product manual for the notebook being diagnosed.
This document instructs how to use LED light codes to identify hardware problems that cause a blank screen. You can use the LED light codes to identify which components are involved in a blank screen condition, and also get steps to help resolve the issue.
Battery power LED blinks
The battery power LED indicates the condition of the power supply. When starting the computer, or when the computer is in operation, use the chart to identify the power condition.
The battery power LED is generally a lightning bolt icon. (If the notebook does not have the lightning bolt battery power LED, consult the product manual.)
|Battery power LED status||Component tested||Error condition|
|Battery power LED off, and Caps Lock/Num Lock LEDs off||Battery or AC Adapter||AC adapter not connected or failure|
Battery low charge or failure
|Battery power LED blinking||Battery||Insufficient battery charge|
Refer to one of the following sections for more information about the battery power status:
If the battery power LED and the LEDs near the Num Lock and Caps Lock keys do not glow when the computer is disconnected from the AC adapter, then the battery has a very low charge or is not charged at all. Try the following two procedures for diagnosing the power issue:
Charge the Battery:
- Connect the AC power adapter, and verify that the battery power LED glows.
- Allow the battery to charge for 15 - 30 minutes.
- Attempt to start the computer.
- If it starts, run the battery test and calibrate the battery.NOTE:For information on how to calibrate the battery use the Testing and calibrating the Battery (Windows 8) or Testing and calibrating the Battery (Windows 7) or Calibrating the Notebook Battery (Windows Vista) or Calibrating the Notebook Battery in Microsoft Windows 98, ME, XP, and 2000 support documents.
- If the computer does not start, if possible, connect a replacement battery to verify that the battery is the problem.
Check the AC Adapter:
- If the computer does not start after charging the battery, remove the battery and connect the AC power supply to the notebook.
- Verify that the battery power LED glows, and then attempt to start the computer.If the LED still does not glow, either the AC adapter has failed, or there is a bad connection between the adapter and the system board.If possible, connect a different AC power adapter to verify that the adapter is the problem, or contact HP for support, which may require a service event.
If the battery power LED (marked by a lightning bolt icon) flashes, the battery might not have sufficient charge to start the computer. (If the notebook does not have the lightning bolt battery power LED, consult the product manual.)
To resolve the problem indicated by this LED error code, try the following steps.
- Check the AC adapter to confirm that all of the plugs are securely seated.
- Connect the notebook to AC power and attempt to start the computer again.
- If the AC adapter features an LED power indicator: Verify that the computer is receiving power from the wall outlet by checking to see if the AC adapter LED is lit.
- If the computer operates on AC power correctly, charge the battery for thirty minutes to one hour and then restart the computer.
NOTE:Charging the battery for this length of time is called "trickle charging." Trickle charging is a continuous constant-current charge at a low rate, which recharges the battery slowly when it is in a deep discharge state. Deep discharge occurs when a battery is left unused for extended periods of time.
New computer in "shipping mode"
When the notebook is used for the first time, the white LED light for the AC power blinks. The battery is still in "shipping mode," when the light continues to blink even when the AC power is connected.
To resolve this issue, turn off the notebook, connect the AC power and allow the battery to charge for at least 30 minutes, then start the computer.
LEDs near Caps Lock and Number Lock keys blink when starting the notebook
The notebook diagnostic utilities use the LEDs near the Num Lock and Caps Lock keys to blink a series of error codes ("blink codes"). At the end of the series the blinking stops. Until the error is resolved, the pattern of blinks will occur any time an attempt is made to start the computer.
The LED lights near the Num Lock and Caps Lock keys will blink if an error is detected during the startup process. The LEDs will blink a number of times in a sequence and then stop. The number of blinks in the sequence indicates what component caused an error when it was being tested during startup.
If the LEDs stop blinking and the computer does not start, press the Power button again to repeat the tests. Count the number of blinks, and use the blink code chart below to identify the error condition.
NOTE:Knowing the number of blinks is helpful when contacting an HP support agent for technical help.
Blink code chart:
|Caps Lock/Num Lock LED blink codes||Component tested||Error condition|
|LEDs blink 1 time||CPU||CPU not functional|
|LEDs blink 2 times||BIOS||BIOS corruption failure|
|LEDs blink 3 times||Memory||Module error not functional|
|LEDs blink 4 times||Graphics||Graphics controller not functional|
|LEDs blink 5 times||System board||General system board failure|
|LEDs blink 6 times||BIOS||BIOS authentication failure|
Error code explanations
The sections below provide some common explanations for each error code ("blink code") listed in the table above.
The computer processor (blink code 1) has stopped functioning properly. Contact HP for assistance.
If a BIOS corruption error occurs (blink code 2), blink codes might not be noticeable. This is because as soon as the computer recognizes the error, it restarts, attempts to recover the BIOS, and then restarts again.
As a result, an extra-long startup process might occur and a message indicating that the BIOS has been recovered might display. If this occurs, update the BIOS on the computer.
NOTE:For information on how to update the BIOS refer to the HP Notebook PCs - Locate and Install Updated BIOS, Drivers, and Software support document.
If the computer does not automatically recover the BIOS, manually perform a BIOS recovery by following these steps:
- Turn off the computer.
- Plug the notebook into power using the power adapter.
- While the computer is still off:
- Press and hold the Windows key and the B key at the same time; AND Press and hold down the Power button on the notebook for 1 second.
- Release the Power button and the keys.
For information on how to restore the BIOS refer to the HP Notebook PCs - Restoring the BIOS support document.
If there is a memory failure (blink code 3), follow the guide in the table below.
|If Using Original Memory||If New Memory Is Added|
|Reseat the memory. |
If reseating the memory does not resolve the problem, try replacing the memory with new memory.
|Reseat the memory. |
If this error code continues to occur after reseating the memory, the problem may be with the memory itself. Take the new memory out of the computer, put the original memory back into the computer, and then retest it.
A computer retailer can reseat the memory, if preferred.
NOTE:Some memory module errors might allow the computer to start, but will then cause the computer to restart and display a blink code.
If the graphics controller fails (blink code 4), contact HP for assistance.
A general system board failure (blink code 5) is the failure of a component not covered by the other LED error codes. Contact HP for assistance.
The BIOS authentication error (blink code 6) is extremely rare. It is the result of a discrepancy between the BIOS and the hardware that is installed on the computer. This error occurs when the BIOS cannot authenticate signatures from the hardware on the system. The purpose of the BIOS authentication is to be sure that no one has tampered with the BIOS on the computer.
If a BIOS authentication failure occurs, the computer automatically performs a BIOS recovery.
If the computer does not automatically recover the BIOS, manually perform a BIOS recovery by pressing all four arrow keys at the same time to cause the BIOS to go to the EFI partition to find and recover the current BIOS.
See additional support documents
HP Notebook PCs - Troubleshooting Error Messages on a Blue Screen that may Occur During Startup or Boot
HP Notebook PCs - Troubleshooting Error Messages on a Black Screen that may Occur During Startup or Boot
Return to HP Notebook PCs - HP Startup Menu Overview for additional topics.
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