IBM 6151 Maintenance And Service Manual page 405

Step 7
If any, exchange the FRUs that are required to run the failing
diagnostic test. Use the removal and replacement procedures in
the section for that FRU (attached devices may have their own
manual).
Try the failing diagnostic test again.
DID THE SAME PROBLEM OCCUR?
NO Go to "Step 12" on page 3-9860-12.
YES Remove the new FRU and install the old FRU again; then
continue on the next page.
(6/88) Problem Isolation Charts 3-9860-7