Maintenance and Service Guide

Blinking lights
Table 8-16 Issues, possible causes, and xes
Items Procedures
Symptoms
Lights blink on keyboard caps
lock/num lock keys
Possible causes
Blinking lights on startup usually indicate a problem with basic functionality of a critical
component (processor, BIOS, graphics cards, memory, etc.) due to loose connection,
defective parts, or recently added parts.
Troubleshooting steps
1. Check for any blink patterns. Count the number of blinks in a sequence, followed by a
pause for a few seconds.
2. See Status, Blinking Lights, and Error Message (7. Status lights, blinking light codes,
troubleshooting lights, and POST error messages on page 87) for corrective actions.
3. If internal hardware components (memory, hard drive, etc.) have been recently added, a
component may not be connected properly. Remove and reseat new components (10.
Reseat cables and connections on page 90) one at a time.
Note Since the display may not be functional, lights are used to indicate an error.
Diagnostics error messages
Table
8-17 Issues, possible causes, and xes
Items Procedures
Symptoms
● Computer has power
● POST error message displays
(Windows logo has not yet
appeared)
Possible causes
Diagnostic error messages indicate a problem. There may be a problem with the instruction
being sent from the BIOS to a hardware component (e.g., keyboard failures), or
incompatible hardware. Can usually be resolved by installing updated rmware for the
component.
Troubleshooting steps
1. See 7. Status lights, blinking light codes, troubleshooting lights, and POST error
messages on page 87 for corrective actions. An example of a POST error message is
shown below.
2. If there is power, you may be able to access BIOS. Reset BIOS to its default condition.
(9. Soft reset (Default Settings) on page 90)
3. Restore hardware to its original condition (i.e., bootable solid-state drive instead of
hard drive).
4. Reseat suspected components and verify connection.
Common issues and possible solutions 103