AUTOMOTIVE WIRING AND ELECTRICAL SYSTEMS

How exactly does this happen? Any number of reasons. Let’s say that you were mounting something under the vehicle’s hood and you unintentionally pinched the parking light wire or pierced it with a screw in the process. All would be fine until you turned on the parking light switch, at which point, the parking light circuit fuse would blow as the switch just connected 12 volts directly to the vehicle’s chassis. The blown fuse just protected the wiring and vehicle from any serious damage. (The value of a fuse should be fairly clear at this point!) Of course, you would now have to determine what caused this and fix the problem. This process is called troubleshooting, and you’ll learn more about how to do this later in the book.

Again, there are any number of reasons for this to happen. Let’s say that you were installing new carpeting in your vehicle and you used a razor knife to cut an opening along the sill plate for the big Torx bolt that holds your seat belt down. If you’re not careful, you could cut through the wiring harness in this area, thereby removing the parking lights in the rear of the vehicle from the circuit. The front lights would still work fine because they are still connected to the circuit. Obviously, this is a simple fix, and it’s covered later in the book.

Wire Resistance Chart We all know there is no such thing as a free lunch. Stranded copper wiring, which is what is typically specified for automotive use, has a certain amount of resistance per foot. This resistance per foot decreases as the gauge of wire increases (indicated by a smaller number; confusing, I know).