PDF wiring diagram merc 500 thunderbolt?? Page: 1 - iboats Sep 22, 2011Hi Guys I need a wiring diagram for an old merc 500 thunderbolt 50 hp from mid 70`s. Anybody?? I do not know where to find the serial number. Hope anyone can help me70's Mercury thunderbolt wiring upgrades? Page: 1Apr 28, 2019Mercury 500 Thunderbolt 50 HP Four 2 Stroke Serial NumberFeb 02, 2017mercury 500 thunderbolt wiring harness fuse and rectifierSep 27, 20131970 mercury 500 thunderbolt wiring ? Page: 1Apr 08, 2003See more results Mercury 500 Wiring Diagram - Wiring Diagram Pictures May 16, 2019Mercury 500 Wiring Diagram (May 16, 2019) - Thanks for visiting Wiring Diagram Pictures. Lots of people have used net for locating info, suggestions, posts or any other resource for their needs. Like you are.