IBM 3270 Maintenance Manual page 320

6. Press 0 (RUN DIAGNOSTIC ROUTINES)
then Enter.
7. Depending on the configuration of your
system, questions about attached devices may
appear on your screen. Press Y or N as
required, then press Enter.
8. Press Y or N (IS THE LIST CORRECT?) then
Enter. (If the list is not correct, follow the
instructions on your screen and correct the
list for the system unit before answering yes.
If you cannot correct the list, you still must
answer yes before you can continue.)
9. Press 0 (RUN TESTS ONE TIME) then Enter.
10. Select 18 (EXPANSION OPTION) then press
Enter.
TESTING - EXPANSION OPTION
X:XX:XX
ERROR -
EXPANSION OPTION 18XXS
Data - XXXX= XX
I
XX SW= X
PRESS ENTER TO CONTINUE
DID YOU GET AN 1820 ERROR CODE?
NO Go to page 3-1800-18.
YES
October 1984 3-1800-5