Advanced Troubleshooting 35Advanced TroubleshootingDiagnostic LightsCAUTION: Before you begin any of the procedures in this section, follow the safety instructions located inthe Product Information Guide.To help you troubleshoot a problem, your computer has four lights labeled "A," "B," "C," and "D" on theback panel (see page 50). The lights can be yellow or green. When the computer starts normally, thelights flash. After the computer starts, all four lights display solid green. If the computer malfunctions,the color and sequence of the lights identify the problem.Light Pattern Problem Description Suggested ResolutionThe computer is in a normal offcondition or a possible pre-BIOS failurehas occurred.Plug the computer into a workingelectrical outlet and press the powerbutton.Memory modules are detected, but amemory failure has occurred.• If you have one memory moduleinstalled, reinstall it (see page 55) andrestart the computer.• If you have two or more memorymodules installed, remove themodules, reinstall one module (seepage 55), and then restart thecomputer. If the computer startsnormally, reinstall an additionalmodule. Continue until you haveidentified a faulty module orreinstalled all modules without error.• If available, install properly workingmemory of the same type into yourcomputer (see page 55).• If the problem persists, contact Dell(see page 94).A B C DA B C D= yellow= green= off
