Tip of the Week (6) for November 8-14, 2015

[Deve]

As old Electronic Technician hack, the most fun part of doing any project is the electrical work. The reason I love it is because there is no confusion about it. I know there is for most people, so let's try and take some of the mystery out of it. Most of the confusion has to do with the differences between AC (Alternating Current) and DC (Direct Current). Your house is AC and your car is DC. Direct Current is mostly a one wire system. This is true because we are measuring the difference in potentials and ground is your baseline. The chassis and the (usually black) ground wire are at the same potential. Consider the word potential as the difference between one level and another. The ground potential is Zero Volts. The Positive wire (usually Red) has the potential of 12 volts. (or 6 for a 6 volt system). This assumes Negative Ground. In fact, this is where the words Positive and Negative Ground came from. In most vehicles our Negative wire is Ground. If you have an old GMC, your's may be Positive Ground. So to measure the voltage potential in your car, we use a Multimeter. You can get a really cheap $5.99 Harbor Freight special or one that does much more for hundreds even thousands of dollars. For your purposes, 90% of what you need can be done with El Cheapo. To measure any wire in your system, always put the black lead on the chassis or ground, and always put the positive wire on the wire you are concerned with.

Remember I said that DC is a one wire system? You will notice your heater, dash lights, fuel sender, even the engine electricals are one wire with the second wire being ground if there even is one. This makes troubleshooting a dream. Can't get power to your dash lights? Clip the black lead to a good ground, and then start probing wires with the positive lead of the Multimeter until you get the 12 volts you are looking for. Always make sure your Multimeter is set to DC Volts before doing this. Remember the most important thing is to never cross probe, or get your positive meter lead in a position to touch both positive and negative at the same time. If you have ever played the game Operation, you can relate to what happens. Most vehicle wiring diagrams are pretty easy to understand. Just be very careful to trace the wires to their correct end. You can always make a printed copy of the wiring diagram, then use a Highlighter Pen to trace them out beforehand. It is not all that dangerous to work on wiring yourself, but if you are not very precise, you can do considerable damage to your vehicle. That is true for everything, so working on your wiring is just another example of precision being of the utmost importance.

Next week we will expand on the electrical system theme and spend more time learning how to use the Multimeter. Seeya next week Sparky!