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Troubleshooting
Dell™Latitude™E6400andE6400ATGand
MobileWorkstationPrecision™M2400ServiceManual
Troubleshooting Tools
Solving Problems
Dell Technical Update Service
Dell Support Utility

Troubleshooting Tools

Diagnostic Lights

Your computer has three keyboard status lights located above the keyboard. During normal operation, the keyboard status lights display the current status
(on or off) of the Num Lock, Caps Lock, and Scroll Lock features. If the computer starts without error, the lights flash, and then turn off. If the computer
malfunctions, however, you can use the status of the lights to help identify the problem.
Diagnostic Light Codes During POST
To troubleshoot a problem with your computer, read the sequence of the keyboard status lights in order from left to right (Num Lock, Caps Lock, and then
Scroll Lock). If the computer malfunctions, the individual lights display a status of either On , Off , or Flashing .
CAUTION: Before you begin any of the procedures in this section, follow the safety instructions that shipped with your computer.
NOTE: After the computer completes POST, the Num Lock light may remain on, depending on your BIOS settings. For more information on using the
system setup program, see the Dell™TechnologyGuide on your computer or at support.dell.com.
Light
Pattern
Problem Description
Suggested Resolution
No memory modules are
detected.
lIf two or more memory modules are installed, remove the modules (see Removing a Memory Module),
then reinstall one module (see Replacing a Memory Module) and restart the computer. If the computer
starts normally, continue to install additional memory modules (one at a time) until you have identified a
faulty module or reinstalled all modules without error.
lIf available, install working memory of the same type into your computer (see Memory).
lIf the problem persists, contact Dell Support.
Memory modules are
detected, but a memory
failure has occurred.
lIf two or more memory modules are installed, remove the modules (see Removing a Memory Module),
then reinstall one module (see Replacing a Memory Module) and restart the computer. If the computer
starts normally, continue to install additional memory modules (one at a time) until you have identified a
faulty module or reinstalled all modules without error.
lIf available, install working memory of the same type into your computer (see Memory).
lIf the problem persists, contact Dell Support.
Memory failed to initialize or
memory is unsupported.
lIf two or more memory modules are installed, remove the modules (see Removing a Memory Module),
then reinstall one module (see Replacing a Memory Module) and restart the computer. If the computer
starts normally, continue to install additional memory modules (one at a time) until you have identified a
faulty module or reinstalled all modules without error.
lIf available, install working memory of the same type into your computer (see Memory).
lIf the problem persists, contact Dell Support.
System board failure has
occurred.
lContact Dell Support.
A possible processor failure
has occurred.
lReseat the processor (see Processor Module).
lIf the problem persists, contact Dell Support.
A possible graphics
card/video failure has
occurred.
lReseat any installed graphics cards.
lIf available, install a working graphics card into your computer.
lIf the problem persists, contact Dell Support.
A possible LCD failure has
occurred.
lReseat the LCD cable (see Display Assembly).
lIf the problem persists, contact Dell Support.
System failed on hard drive
initialization.
lReseat the hard drive (see Hard Drive).
lIf the problem persists, contact Dell Support.