System status LEDs are located on the front of the HMC, rear of the HMC, and the system board. These LEDs help to locate the source of the error. The 7042-CR4 HMC also has light path diagnostic LEDs to help you find the cause of the problem.

When the LEDs are lit to indicate an error, they remain lit even when the HMC is turned off, provided that the HMC is still connected to power and the power supply is operating correctly. This feature helps you to isolate the problem when the operating system is shut down.

7042-CR4 Model

On the 7042-CR4 HMC, if an error occurs, view the light path diagnostic LEDs in the following order:

1. View the operator information panel on the front of the HMC:
   • If the System information LED is lit, it indicates that information about a suboptimal condition in the HMC is available in the BMC log or in the system-error log.
   • If the System-error LED is lit, it indicates that an error has occurred. (Continue to the step 2.)
     
     
2. View the LEDs on the light path diagnostic panel, which is located on the top of the operator information panel assembly. Note any LEDs that are lit on the light path diagnostic panel, and then close the unit. (Refer to the Service Guide for Deskside and Rack-mounted Consoles manual for information about the LEDs located on the light path diagnostic panel. )
   
   The system service label on the top of the HMC provides an overview of internal components that correspond to the LEDs on the light path diagnostic panel.
   
   The information on the light path diagnostic panel and the system service label can often provide enough information to diagnose the error.
   
   
3. Remove the HMC cover and look inside the HMC for lit LEDs to further diagnose the error.

7042-C06 Model

On the 7042-C06 HMC, if an error occurs, view the error LEDs in the following order:

1. Check the front-panel assembly on the front of the HMC. If the System-error LED is lit, it indicates an error has occurred.
   
   
2. Check the front and rear of the HMC to determine whether any component LEDs are lit.
   
   
3. Remove the HMC cover and look inside the HMC for lit LEDs on the system board. Certain components inside the HMC have LEDs that will be lit to indicate the location of a problem. For example, a DIMM error will light the LED next to the failing DIMM on the system board.
   
   The system service label on the top of the HMC provides an overview of internal components. This information can often provide enough information to correct the error.