re: Squirrels chewing wires in vehicles.

Squirrels caused damage to both vehicles under carport. Wiring harness destroyed and a nest from hell was built in engine compartment.
How to avoid in the future
1) Keep the hood open while you are home. Squirrels like dark warm places - let the light shine in and noise enter the engine compartment.
2) Placed ammonia on a rag. Placed rag in a ziplock bag with some holes cut in the ziplock above the rag. Zip tied to bar near battery where the original damage occurred.

Have not had any signs of a single squirrel since - 3 years.