IBM 6151 Maintenance And Service Manual page 375

Step 5
1.
Set the system unit power switch to Off.
2. Connect the power connector to the diskette drive.
3. Be sure the power has been off 30 seconds; then set the power
switch on the system unit to On.
4. Wait 15 seconds; then answer the following question.
AJZIH59
IS THE POWER-ON INDICATOR ON?
NO Exchange the diskette drive; then go to "Step 14" on
page 3-8800-14.
YES
Exchange the fixed-disk drive; then go to "Step 14" on
page 3-8800-14.
(6/88) Problem Isolation Charts 3-8800-5