IBM 6151 Maintenance And Service Manual page 274

Step 22
One of the FRUs still installed in the system unit is failing. The
most likely failing order depends on the failing area. The failing
area can be related to the types of FRUs that you have exchanged
that did not fix the problem. Find the area that best describes your
problem in the table below; then go to that step.
Failing Area Go to Step
Displays
"Step 23" on page 3-0060-25
Fixed-disk and diskette
"Step 24" on page 3-0060-26
drives
Keyboard
"Step 25" on page 3-0060-27
Other or unknown area
"Step 26" on page 3-0060-28
3-0060-24 Service Manual