Light path diagnostics LEDsThe following table describes the LEDs on the light path diagnostics panel andsuggested actions to correct the detected problems.Note: Check the system-error log or system event log for additional informationbefore replacing a FRU.Table 4. Light path diagnostics panel LEDsv Follow the suggested actions in the order in which they are listed in the Action column until the problem issolved.v See “Parts listing” to determine which components are customer replaceable units (CRU) and whichcomponents are field replaceable units (FRU).v If an action step is preceded by “(Trained service technician only)”, that step must be performed only by atrained service technician.LED Description ActionNone, but thesystem error LEDis lit.An error has occurred and cannotbe isolated. The error is notrepresented by a path.Use the Setup utility to check the system error log forinformation about the error.OVER SPEC The power supplies are usingmore power than their maximumrating.If the OVER SPEC LED on the light path diagnostics panel islit, or any of the six 12 V channel error LEDs (A, B, C, D, E,or AUX) on the system board are lit, use one of the followingprocedures.If the 12 V channel A error LED is lit, complete the followingsteps:1. Turn off the server and disconnect the power from theserver.2. Remove the optical drive, fans, hard disk drives, and harddisk drive backplane.3. Restart the server to see whether the problem remains.4. Reinstall each device that you removed in step 2 one at atime, starting the server each time, to isolate the failingdevice.5. Replace any failing device.6. (Trained service technician only) Replace the systemboard.If the 12 V channel B error LED is lit, complete the followingsteps:1. Turn off the server and disconnect the power from theserver.2. Remove the PCI riser card in connector 1, all DIMMs, andthe microprocessor in socket 2.3. Restart the server to see whether the problem remains.4. Reinstall each device that you removed in step 2 one at atime, starting the server each time, to isolate the failingdevice.5. Replace any failing device.6. (Trained service technician only) Replace the systemboard.(Continued on the next page)20 IBM System x3550 M3 Type 4254 and 7944: Installation and User's Guide
