Light Path Diagnostics - IBM XSERIES 255 TYPE 8685 Hardware Maintenance Manual And Troubleshooting Manual

Release latch
For more information about the ac and dc power LEDs, see "Power-supply LED
errors" on page 145.

Light path diagnostics

You can use the light path diagnostics feature built into your server to quickly
identify the type of system error that occurred. Your server is designed so that LEDs
remain illuminated when the server shuts down, as long as the power supplies are
operating properly. This feature helps you to isolate the problem if an error causes
the server to shut down.
Diagnostic panel LEDs
The following illustration shows the location of the error LEDs and the Remind
button on the light path diagnostics panel. See "Diagnostic panel system error LED"
on page 130 for information on identifying problems using these LEDs.
Notes:
1. If the memory is configured for 2-way or 4-way memory interleaving and a
2. The light path diagnostics panel is also called the LED card or the diagnostic
32
xSeries 255 Type 8685: Hardware Maintenance Manual and Troubleshooting Guide
Hot-swap fan
Release
latch
Power supply
AC power LED
DC power LED
Handle
(open position)
MEMORY
NMI ISMP LOG D1
PCIA PCIB PCIC PCID DASD D2
PS1 PS2 CPU VRM TEMP D3
PS3 PS4 FAN D4
OVER NON
SPEC REDUND
Light Path
D5
Diagnostics™
D6
REMIND
single DIMM fails, the lights for all of the interleaved DIMMs on that bank will be
lit. See "Memory errors" on page 34.
LED panel.
D7
D8
D9
D10
D11
D12