Sun Microsystems 220R service manual Caps Lock Compose Scroll Lock Num Lock Failing FRU

To indicate the beginning of POST diagnostics, the four LEDs briefly light all at once. The monitor screen remains blank, and the Caps Lock LED flashes for the duration of the testing.

If the system passes all POST diagnostic tests, all four LEDs light again and then go off. Once the system banner appears on the monitor screen, the keyboard LEDs assume their normal functions and should no longer be interpreted as diagnostic error indicators.

If the system fails any test, one or more LEDs will light to form an error code that indicates the nature of the problem.

Note - The LED error code may be lit continuously, or for just a few seconds, so it is important to observe the LEDs closely while POST is running.

The following table provides error code definitions.

Caps Lock	Compose	Scroll Lock	Num Lock	Failing FRU
On	Off	Off	Off	Main logic board
Off	On	Off	Off	CPU module 0
Off	On	On	Off	CPU module 1
On	Off	Off	On	No memory detected

Diagnostics and Troubleshooting 213