38     IBM Desktop System HMM
Index of Symptoms, Messages, Error 
Codes, or Beeps 
How to Use Error Messages:
 Use the messages, 
error codes, and beeps combinations that occur to 
diagnose failures. If more than one failure occurs, 
begin the diagnosis from the first failure that 
appeared. The cause of the first failure can result in 
false messages, error codes, or beeps. If you did not 
receive any messages, error codes, or beeps, see if 
the symptom is listed in “Table 2-3 Error Symptoms 
List” on page 45.
CAUTION: 
 When you have deemed it necessary to 
replace a FRU, and have done so, you must 
run a total system check to ensure that no 
other activity has been affected by the change. 
This system check can be done through the 
diagnostics program (Select Diagnostics, then 
select and execute All Tests from PC-Doctor).
POST:
 Some diagnostic aids are resident in the 
machine, such as the Power-On Self Test (POST). 
The machine performs the POST each time it is 
powered on. Use this information throughout the 
diagnostic procedures. The POST is a series of 
system checks and initializations that verify the 
correct operation of the base system. 
After a successful POST, the system attempts to load 
operating system. The system can be customized for 
different startup (boot) methods by the Configuration/
Setup Utility. “Startup Options” on page 20.
The system's default startup sequence automatically 
looks for the operating system files in the hard disk if 
these files are not found in the diskette.
WARNING: 
Remember that POST does not test all 
areas, but only those that allow the system to 
operate well enough to run the diagnostics 
program. 
Table 2-1 lists BIOS error codes, messages, and their 
possible causes. Table 2-2 lists BIOS beeps and their 
possible causes. Table 2-3 lists error symptoms and 
their possible causes. The most likely cause is listed 
first. Make sure you complete all items in the cause or 
“Action/FRU” column. When servicing a system, 
always begin with “Start” on page 33.