Chapter 3. Identifying FRUs Locate FRUs and CRUs The exploded illustrations help Lenovo service technicians identify FRUs or CRUs that they may need to replace when servicing a customer’s computer. Figure 1. Exploded view Table 3. FRU (CRU) categories © Copyright Lenovo 2021 23 No. FRU (CRU) category 1 Upper case 2 Heat sink 3 System fan 4 I/O board 5 Fingerprint reader* 6 Battery pack