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Message: <blockquote data-quote="smoka" data-source="post: 6276244" data-attributes="member: 606721">This guy is right but I find it much easier to calculate resistance by measuring the grounds for voltage gain (opposite of voltage drop).But its true, you can't accurately measure a ground unless there is current running through it. Electricians have a tool thats opposite but similar its called a megger, they can hook up a wire and run voltage through it and check for any changes of resistance, this can tell you if a wire is good or not. Vehicles won't work this way since everything is connected to chasis but in theory its the same test that is needed. So we will do the similar test as a megger, but we will use your amp to pull the power and your meter to watch the resistance. Remember that you can use voltage drop to calculate resistance. In this case, we'll use voltage gain (opposite of drop) since we are dealing with the grounds.If you want to compare two ground points resistance, do this: Connect one side of your dmm to your neg battery post. This is your reference ground. Then with your 2nd lead you will have to use a long piece of wire as an extension, it can be a thin wire. Now connect your 2nd lead to the 1st ground location where your amp is grounded. Play some test tones or a song with constant bass to get a good current flow going through the ground. Set the meter to dc volts. If you see a voltage generate when the music is playing, that means you are getting a higher resistance at that ground point. Check the 2nd ground this same way. Whichever ground shows a lower voltage (should really be 0 volts at all times), then that is the better ground point.Or you can save yourself the trouble and just run a 1/0 ground from the front along with your chassis point. That usually takes care of any problems.</blockquote>

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