over the years, i have uncovered untold issues related to wiring that is located under, or close to, the battery.
i blame this on the battery out-gassing, and the fumes over time eating the harness and nearby connections.
the more the harness is stuffed near the battery, the more problems found.
as the battery ages, the more out-gassing occurs. daily drivers are more prone to this, as nothing is really looked at until a problem or failure pops up.