Rodents eating your wire harness? Try living in the Sonoran desert of Arizona for 15 years. I and my dogs would dispatch 100 to 150 Pack Rats (Wood Rats weighing up to and over 5 lbs/2 kg) every year just in the area around the ranch house. They get into everything (including the walls of our house once). They got into every vehicle we had and ate everything from my paper maintenance logbook in the glove box, to rubber shifter boots, to spark plug wires, to O2 sensors on catalytic converter, the rubber portion of tire valve stems........so on and so on. They terrorized an 1988 Isuzu Trooper, 1996 Jeep Cherokee, 1986 Ford F-350 Pickup and a 1999 Toyota Tacoma (so brand made no difference). If it was rubber, vinyl or plastic, it was fair game. This does not include the rat B*stard that filled the catalytic converter on my wife's Tacoma with dry dog food causing so much back pressure it would not keep running (had to remove entire exhaust system and found several dead rats inside). Or the one that built the Rat Taj Mahal in the engine compartment of my Jeep engine in one night, covering every square centimeter of engine with grass, weeds, sticks, juniper tree branches, discarded 7-11 burrito wrappers, dog food, dog POOP.......
Now, here is the kinder/gentler Cowboy fix. Buy your self a box of unscented dryer sheets (we used Bounce or Snuggle), a bag of small zip ties or roll of bailing wire. You can use scented ones, but for some reason, unscented worked better on the rats in the the Desert Southwest. Now, take 3 or 4 (requires a bit of experimentation first month) and wrap one each around a length of wiring harness inside the engine compartment (I did one on each side of engine and one along firewall) securing with zip ties, or a spiral wrap of bailing wire. Find locations no closer than 10 inches/2500mm to hot engine parts, and don't install on radiator hoses, air conditioning lines (rubber or metal), exhaust pipes and similar if you want to avoid engine fire. Wiring harness going along top of fire wall and over top of fenders to headlights are safest, but you may not get full effect and will have to move next group closer to engine. You will need to replace about every 30-60 days depending on driving habits and ambient temperatures. What happens is the heat from the engine warms the dryer sheets and releases the anti-static chemicals, which ror some reason, bothers the rats and keeps the little critters away. We only did this trick in the engine compartment, but the rats never attacked any other part of our vehicles equipped in this fashion for the next 10 years we stayed in Arizona.