This reminds me of my old neighborhood where everyone had aluminum wiring and the only approved method was a copalum connector, and the tool to do it was super expensive, yet electricians were getting big $$ per receptacle to recrimp these connections. Luckily only my 220 were aluminum and not in need of fixing.
If I need to redo the connections in the bulkhead I am confident I can do it with the right tool. Probably not going to buy it just to do the jumper. Hopefully I can clean the bulkhead and it will look fine, and figure out why my ammeter showing such a high charge upon acceleration.
I recently added an air/flow gauge but am almost positive it was connected to ignition 12V.