On two separate occasions, squirrels got up into the engine compartment of a friend’s truck and chewed thru the wiring harnesses. The second time cost over $3,000 to repair.
Mice had a good meal on the headlight wiring of my brand new company car a month after I got it. Of course the manufacturer wouldn’t stand behind it and wanted to charge us $1500 for a new wiring harness.
A few minutes with a wire nut also fixed it.