Back to Contents PageTroubleshootingDell™ Latitude™ E5400 and E5500 Service ManualTroubleshooting ToolsSolving ProblemsTroubleshooting ToolsDiagnostic LightsYour 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 computermalfunctions, however, you can use the status of the lights to help identify the problem.Diagnostic Light Codes During POSTTo 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 thenScroll Lock). If the computer malfunctions the individual lights display a status of either On , Off , or Flashing .Hardware TroubleshooterIf a device is either not detected during the operating system setup or is detected, but incorrectly configured, you can use the Hardware Troubleshooter toresolve the incompatibility.Windows XP:1. Click Start® Help and Support.CAUTION: Before you begin any of the procedures in this section, follow the safety instructions that shipped with your computer. For additionalsafety best practices information, see the Regulatory Compliance Homepage on www.dell.com at: www.dell.com/regulatory_compliance.NOTE: After the computer completes POST, the Num Lock light may remain on, depending on your BIOS settings. For more information on using thesystem setup program, see the Dell™ Technology Guide on your computer or at support.dell.com.LightPatternProblem Description Suggested ResolutionNo memory modules aredetected.l If two or more memory modules are installed, remove the modules (see Removing a Memory Module), thenreinstall one module (see Replacing a Memory Module) and restart the computer. If the computer startsnormally, continue to install additional memory modules (one at a time) until you have identified a faultymodule or reinstalled all modules without error.l If available, install working memory of the same type into your computer (see Memory).l If the problem persists, contact Dell Support.Memory modules aredetected, but a memoryfailure has occurred.l If two or more memory modules are installed, remove the modules (see Removing a Memory Module), thenreinstall one module (see Replacing a Memory Module) and restart the computer. If the computer startsnormally, continue to install additional memory modules (one at a time) until you have identified a faultymodule or reinstalled all modules without error.l If available, install working memory of the same type into your computer (see Memory).l If the problem persists, contact Dell Support.A possible processorfailure has occurred.l Reseat the processor (see Removing the Processor Module).l If the problem persists, contact Dell Support.A possible graphicscard/video failure hasoccurred.l Reseat any installed graphics cards.l If available, install a working graphics card into your computer.l If the problem persists, contact Dell Support.A possible display failurehas occurred.l Reseat the display cable (see Removing the E5400 Display Assembly).l If the problem persists, contact Dell Support.SPD data indicates allSODIMMs are unusable.l Remove the unusable memory module (see Removing a Memory Module).l Replace with a usable memory module (see Replacing a Memory Module).