IBM pSeries 670 Service Manual page 233

Step 152h-52
Are all the green "power good out" LEDs of both I/O subsystem DCAs off?
Yes Go to "Step 152h-53".
No Call for support.
Step 152h-53
Replace the parts in the following list, one at a time and in the order listed:
v I/O subsystem backplane at P1
v I/O subsystem backplane at P2
Step 152h-54
Turn on the power.
Step 152h-55
Did the system stop with the same error code as recorded in "Step 152h-1" on page 206?
Yes Go to "Step 152h-56".
No The part just replaced is defective. Replace it. This ends the procedure.
Return the system to its original configuration.
Go to "MAP 0410: Repair Checkout" in the RS/6000 and Eserver pSeries Diagnostic Information
for Multiple Bus Systems.
Step 152h-56
Turn off the power.
Make sure all the green "power good out" LEDs of both I/O subsystem DCAs are off.
Step 152h-57
Have all the cards listed in "Step 152h-53" been replaced with new or original cards?
Yes Call for support.
No Go to "Step 152h-53".
Chapter 3. Maintenance Analysis Procedures
213