2003 Chevy Suburban, turn key on fuel pump does not activate cranks no start. Fuel gauge reads empty and fuel light on. Fuel tank full. problem is intermitent.

sounds like a bad fuel pump its also part of the sending unit.

Agree with above and also could be a bad connection at sending unit/fuel pump could cause intermittent problem. check fuel pump/sending unit circut....

I wiggled the harness going into fuse box under the hood and the fuel pump activated? Which pin or wire could be faulty?

check relay or swap it with another

I agree, swap out the relay with a new one, check connections