Tye Muwps

As an auto mechanic I see so many electrical issues from dirty connectors. My pro tips: Skip the Coca-Cola or other home remedies - they can leave sticky residues. Use proper electrical contact cleaner from an auto parts store. For really baked-on corrosion a mix of vinegar and baking soda works but you MUST rinse and dry incredibly well as vinegar is acidic.

For the actual metal pins inside multi-pin connectors (like trailer plugs) get a set of electrical contact cleaning tools - they have tiny brushes that fit into the sockets. A dab of dielectric grease after cleaning is crucial especially in marine or off-road environments. And check those ground connections too! Often the problem isn't the positive terminal but a corroded ground point on the chassis. Clean both ends of the circuit for best results.