A device backplane might be failing.

Perform the following:

1. Does the SRC that sent you here begin with 506x, or are you working with an attached 5786 or 5787 disk expansion unit?
   • No: Continue with the next step.
   • Yes: Replace the SCSI interface card of the 5786, 5787 Disk Expansion Unit. See the table below for location and part number information. If this does not fix the problem, continue replacing the other failing items in the failing item list. If the other failing items do not fix the problem, replace the disk expansion unit chassis.
2. Does the SRC that sent you here begin with a 509A or are you working with an attached 5886 disk expansion unit?
   • No: Continue with the next step.
   • Yes: Replace the mid-plane of the 5886 Disk Expansion Unit. See the table below for location and part number information.
3. Replace the device backplane, use the device backplane information in the Service Action Log to determine the part number.

Use the following table to determine the part number for the field replaceable unit (FRU):

CCIN or FFC	Type and model	Part number	Description	Location code
506D	5786, 5787	12R9040	SCSI interface card 1 (top left), SCSI repeater card assembly, dual	Un-C2
506E	5786, 5787	12R9042	SCSI interface card 1 (top left, SCSI repeater card assembly, single)	Un-C2
506D	5786, 5787	12R9040	SCSI interface card 2 (top right), SCSI repeater card assembly, dual	Un-C3
506E	5786, 5787	12R9042	SCSI interface card 2 (top right), SCSI repeater card assembly, single	Un-C3
506D	5786, 5787	12R9040	SCSI interface card 3 (bottom left), SCSI repeater card assembly, dual	Un-C4
506E	5786, 5787	12R9042	SCSI interface card 3 (bottom left), SCSI repeater card assembly, single	Un-C4
506D	5786, 5787	12R9040	SCSI interface card 4 (bottom left), SCSI repeater card assembly, dual	Un-C5
506E	5786, 5787	12R9042	SCSI interface card 4 (bottom left), SCSI repeater card assembly, single	Un-C5
509B	5886	42R7898	5886 SAS expansion unit midplane	Un-C5