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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 along the path of the front panel, the light path diagnostics panel, 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, view the light path diagnostics LEDs in the following order:

  1. Look at the operator information panel on the front of the server.
    • If the check log LED is lit, it indicates that an error or multiple errors have occurred. The sources of the errors cannot be isolated or concluded by observing the light path diagnostics LEDs directly. A further investigation into IMM2 system-event log or system-error log might be required.
    • If the system-error LED is lit, it indicates that an error has occurred; go to step 2.
    The following illustration shows the operator information panel.
    Figure 1. Operator information panel
    Operator information panel
    The following table describes the LEDs on the operator information panel and suggested actions to correct the detected problems.
    Table 1. The suggested actions to correct the detected problem for each LED light
    • Follow the suggested actions in the order in which they are listed in the Action column until the problem is solved.
    • If an action step is preceded by (Trained technician only), that step must be performed only by a trained technician.
    • Go to the IBM support website at Lenovo Support to check for technical information, hints, tips, and new device drivers or to submit a request for information.
    LEDDescriptionAction
    System locator (blue)Use this LED to visually located the server among other servers. You can use IBM Systems Director or IMM2 to light this LED remotely. 
    Check log (yellow)An error has occurred and cannot be isolated without performing certain procedures.
    1. Check the IMM2 system event log and the system-error log for information about the error.
    2. Save the log if necessary and clear the log afterwards.
    System-error (yellow)An error has occurred.
    1. Check the light path diagnostics LEDs and follow the instructions.
    2. Check the IMM2 system event log and the system-error log for information about the error.
    3. Save the log if necessary and clear the log afterwards.
  2. Look at the light path diagnostics panel on the front of the server. Lit LEDs on the light path diagnostics panel indicate the type of error that has occurred. The light path diagnostics panel LEDs are visible through the bezel. Look at the system service label on the top of the server, which gives an overview of internal components that correspond to the LEDs on the light path diagnostics panel. This information can often provide enough information to diagnose the error.