Ground/earth connections are often ignored, but they along with the metalwork of the chassis perform as half of each 12 volt circuit. and can often be the first place in a circuit for poor connections to begin.
Earths/grounds are often ignored, whereas the imagined live/hot side of the circuit tends to be that which is well insulated and waterproofed.
Earth faults can throw up all sorts of issues that seem far less obvious to resolve as they can effect more than one circuit and depending on how many circuits might be grouped at one earth connection point on the chassis, and that the level of crud/corrosion/ looseness of connection can vary with vibration, perhaps related to the number of circuits are switched on at any one time and connected to earth at that one point.
An ideal earth connection would be one where the connection to the chassis it bare metal to bare metal, and that many earth connections can be in out of the way places on the underside, what better place for crud to build up and corrosion to begin..?
It can pay dividends to pay attention to earth connections, and if they are looking corroded taking them apart cleaning them up and putting them back together can brighten lights up, increase charge rates and reduce the chance of failures... Though once you have cleaned all those connections up to the chassis it seems best to give them an overall covering of petroleum jelly, grease or paint to stop the nice clean metal from further corrosion..?
