Testing a car relay involves the use of a 12-volt source, such as a car battery, and a multimeter that is capable of reading resistance. Find out how to listen for clicks and tones that indicate a functioning relay with help from an auto mechanic in this free video on car repairs and mechanics.
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How to test a car relay. To test a car relay, you're going to need a twelve volt source. In this case, we're using this car battery. You're going to need a multimeter that's capable of reading resistance, ideally one that has a continuity meter on it so that it gives you an audible tone when you have continuity. With the meter set on resistance, you take your relay and the pulls that you're looking for continuity between are going to be labeled thirty and eighty seven. And you're going to take the clips from your meter and you're going to clip them on to the thirty and the eighty seven, and then you're going to take a set of test leads. In this case these are battery clamps. You're going to attach them to your battery. You're going to take the other end and you're going to touch it to the eighty six and eighty five pins on the relay. And what you should hear is a click from the relay and you should hear your tone on the meter. And that indicates that the relay is functioning. And when you let off with the lead, the continuity goes away, the meter stops and that indicates that the relay is shut.