The tightwad in me says ... I'd just splice and well insulate from moisture, then test.
This made me question WHY he did this. One possible idea is maybe he had pulled the emergency brake wire which locked them up, and not knowing any better that was his way of freeing them up for travel???
former 2008 Jayco Eagle 29.5 RLS
former 2014 F250 6.7 4X4, CC LB