How To Tell if Your Car is Positive or Negative Ground

It is not always easy to tell if your car is positive or negative ground. A lot of systems depend on you knowing this essential information. In this video, our tech department shows you a quick and accurate way to tell.

Many older British cars were built to be positive ground. Later, for a variety of reasons, many of those cars were converted to negative ground. And of course, many British cars were built negative ground right off the bat. If you’re buying an electronic ignition, electric fuel pump, or radio, it’s important to know which way your car is wired.

The easiest and most accurate way to tell is to look at your battery terminals and cables. One cable connects to the positive terminal, one cable connects to the negative. In this particular case, the negative cable goes to the frame of the car. This is a negative ground car. Over here, they’re using duel 6-fold batteries to do the exact same job. In this case, two of the terminals are used by the jumper, which connects the two batteries together, leaving us with one positive and one negative terminal. In this set up, the positive cable is the one that goes to ground. These batteries are being used in a positive ground car. They can just as easily be used in a negative ground car. Always remember if you work with a battery that doesn’t have any markings, the larger terminal is always the positive.