Arif Posted September 2, 2003 Share Posted September 2, 2003 OK I majored in accounting and not electrical engineering. How do you test circuits with a multimeter? I am trying to check my battery, fuse block in the engine compartment, and the alternator (but I think it has to be running in order to check the alt.) Also where do I connect the leads pos and neg to in order test these circuits? Please provide as much detail as possible. What setting does the mutlimeter have to be set at in order to test these items? The one I bought from autozone has DV, ACV, DCA, hFE, and 10A settings. The directions suck as they don't tell you what each one is for. I already blew the fuse screwing around with it. I figured I better stop before I fry myself or my Z. Although if the Z was fried I wouldn't need the answer to these questions. Quote Link to comment Share on other sites More sharing options...
blueovalz Posted September 2, 2003 Share Posted September 2, 2003 DV and DCA (Direct Current Volts and DC Amps) will be the two settings you'll use for testing. Never use the DCA unless you know the current or amps flowing through the circuit is less than the limit of the meter, or meter setting (one way to blow a fuse or kill the meter). On the DV, place the red (+ or positive lead, making sure it is correctly plugged into your meter) on the battery side of the circuit you are testing. If you are unsure of what is the positive or negative side, place the meter setting to the highest voltage setting prior to testing. This way if the leads are reversed, the meter movement will not take as bad a "hit" as if it was on a lower (e.g 12volt) setting. If everything looks good (slight meter movement) go ahead and place the voltage setting back to one that is close to the voltage being measured (e.g 12 vdc). Testing from the battery up to a switch verifies the wire is good, then across the closed switch verifies the switch is good, and so on, for each circuit. Any breaks will result in no voltage being shown when you get on the load side of the break. Quote Link to comment Share on other sites More sharing options...
zcarnut Posted September 2, 2003 Share Posted September 2, 2003 I hope you got a digital meter and not an analog one... To answer one of your questions: The quickest way to check an alternator is just to measure the battery terminal voltage. With the ignition OFF you should read 12.0 to 12.9V depending on the state of the battery's charge and the temperature. Use the DCV function. With the engine running you should see an increase in battery voltage because the only way to charge a battery is to force current through it in the reverse direction. And to do this, you must first exceed the terminal voltage. So, with a good alternator, the battery terminal voltage will then measure 13.5V to 14.5V (with the engine running). Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted September 2, 2003 Share Posted September 2, 2003 Good point about testing current...don't do it unless you know what you are doing. If you are tracing live circuits, use the voltage settings. Just connect your black lead to the chassis or the negative lead of the battery. Unless your alternator is totally hosed, you will always read positive voltage with the red lead. To test a fuse, check for voltage on both sides - it should be the same (and at battery voltage) if the fuse is good. And if you come across a test procedure or otherwise that requires a continuity test, you can use the resistance (ohms) setting on the meter, but remember - the circuit must not be powered, or your results will not make sense. It's also possible to damage the meter. Quote Link to comment Share on other sites More sharing options...
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