I'll apologize up front for my complete lack of electrical skills(myi biggest weakness). Im changing uut the trashed top under hood fuse box and while removing and relocating terminal by terminal I get to the fuel pump relay. It's a 5 pin relay and there is only 4 terminals. No homeless or loose wires, correct relay(7866), schematic looks to show 4 wires in but then wouldn't it be just a 4 pin relay? Ugh I'm horrible with electrical and now confused AF. If anybody can chime in and help me out it would be much appreciated

 

Just looked at mine for you and your correct its a 5 pin relay going to 4 wires in the fusebox Just what GM used nothing to be concerned about , good luck

 

Thanks I feel better now. Leave it to gm to make something simple confusing.