Troubleshooting 3-3
System Motherboard LEDs
You may see the system motherboard LEDs by looking through the grate at the back
of the machine. The normal state of the LEDs are shown in Figure 3.1.
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If either IOD0 or IOD1 LEDs are off, the system bus to PCI bus bridge has
failed. Replace the system motherboard.
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If the Fan Fault LED is ON, at least one of 4 fans is broken. If this condition
occurs while the system is up and running, an error message identifying the FRU
is printed to the console. If this condition occurs during a cold start, identifying
which fan caused the Fan Fault depends upon which type of console the system
has. If your console is a serial terminal (for OpenVMS, or DIGITAL UNIX),
the error identifying which fan failed is reported at the console. If your console
is a graphics monitor (for NT) reset the system and watch the OCP display.
During the first 30 seconds, one of the following message should occur:
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SYSx Fan Failed where x = 0 or 1
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CPUx Fan Failed where x = 0 or 1
Replace the failing FRU
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If the Temp OK LED is OFF, an over temperature condition exists. Several
things can cause this condition: blocked air-flow, temperature in the room where
the system is located is too high, the system card cage is open and air is not
channeled properly over the system. Fix any of these conditions, if possible.
The over temperature threshold is programmable and is controlled by the
environment variable over_temp. Its default is 55 degrees C. After the system
has cooled down and can be powered up, you can change the threshold. If you
do this and the temperature inside the system gets too hot, it is likely that system
errors will occur and the system may crash.
