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Light path diagnostics

Light path diagnostics is a system of LEDs on various external and internal components of the server that leads you to the failed component. When an error occurs, LEDs are lit on the operator information panel on the front of the server, then on the failed component. By viewing the LEDs in a particular order, you can often identify the source of the error.

When LEDs are lit to indicate an error, they remain lit when the server is turned off, provided that the server is still connected to power and the power supply is operating correctly.

Before you work inside the server to view light path diagnostics LEDs, read the safety information Safety and Handling static-sensitive devices.

If an error occurs, proceed as follows:
  1. Look at the operator information panel (see Operator information panel) on the front of the server.
    • If the check log LED is lit, it indicates that information about an un-isolated fault condition in the server is available in the IMM event log or in the system-event log.
    • If the system-error LED is lit, it indicates that an error has occurred.
  2. Remove the server cover and look inside the server for lit LEDs. Certain components inside the server have LEDs that are lit to indicate the location of a problem.

    The system service label inside the server cover provides an overview of internal components that correspond to errors indicated by the operator information panel or LCD operating panel assembly (see Operator information panel or LCD operating panel assembly. This information can often provide enough information to diagnose the error.

    Note
    You do not have to remove the server cover to view the LEDs on hard disk drives and power supplies.
The following illustration shows the LEDs on the system board.
Figure 1. System board error LEDs
System board error LEDs

The LCD operating panel assembly displays a current list of errors reported by the system and other information. See the LCD operating panel assembly for more information about the LCD operating panel assembly.