Diagnostic LED PCA Figure 6-172 8-bin Mailbox Diagnostic LED PCA (1 of 2) 1 Locate the Diagnostic LED that is on the back side of the 8-bin Mailbox (Figure 6-172, callout 1). 2 Remove the Back Cover from the 8-bin Mailbox (see Figure 6-150). 356 Chapter 6 Removal and Replacement C4085-91087