IBM pSeries 690 Service Manual page 248

Step 152c-55
Turn off the power.
Make sure all amber logic-power LEDs of all installed processor subsystem DCAs are off.
Step 152c-56
Has the system backplane been replaced?
Yes Call for support.
No Go to "Step 152c-52" on page 231.
232 Eserver pSeries 690 Service Guide