Biodegradable wiring in a vehicle? I don't think so. They would be crazy to put wiring into a car that degrades, especially with vehicles staying in service longer and longer. And to the extent that cars are recycled and not put into landfills, that would be another reason not to need to use biodegradable wiring.
Wiring, where it has issues in any vehicle, is usually at the clips where the wiring attaches to the part. Moisture has an access point and can create corrosion, especially in climates where road salt is used for winter road maintenance.
I had an issue with my oil level sensor. Turns out it was corrosion in the wiring clip connection between the sensor and the wire. Cleaned the corrosion, problem solved.