Why are rodents chewing up car wiring? | KIRO-TV Rodents chewed through both wiring harnesses, belts and hoses. When he found out soy is being in the wire coating of many vehicles, Msaid, "Rats probably like it -- lunchtime. So that can't be Does your car have soy based wiring? - How to Prevent Rats Jan 14, 2018$440+ each time! Now the check engine light is on again. We’ve tried putting rat poison stations under the car, and taping rat poison inside the engine compartment. But we really don’t know if its rats, squirrels, or something else. Seems to us that Ford ought to be armoring the wiring harness.