IBM 5531 Operator's Manual page 94

Test 1500 - SOLe Adapter
Do you have an IBM Synchronous Data Link Control Adapter installed in your system?
NO Continue with the next test.
YES - Did the following error message appear on your screen?
YES Have the system unit serviced.
NO The system has completed this test successfully. Continue with the next test.
Chapter 5. Problem Determination Procedures
5-1500-1