How To Test And Repair Alternator

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Not sure if your alternator is in tip top shape? It'due south hard to tell whether or not an alternator works if you don't know what to look for. The easiest style to examination it is by using a voltmeter. If you're well in tune with your car, there are a few other methods y'all may try equally well. This test is to requite a general health of your alternator and battery. Some newer vehicles may have computer controlled charging systems and would require additional testing.

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   Buy a voltmeter. You tin detect one at any auto parts shop for less than $20.^[ane] Don't worry almost getting an expensive one; a inexpensive voltmeter volition do for this purpose.

   • If you have a multimeter, you tin can use that instead. A multimeter measures voltage as well equally other electrical properties such every bit current and resistance. Yous want to measure voltage when you're checking your alternator.^[2]

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   Check the battery first. The battery is needed to start the vehicle, which, in turn spins the alternator at sufficient speed to keep the bombardment charged. This means that if your battery is as well low, y'all volition be unable to start the vehicle and thus you will too be unable to exam the alternator, rendering whatsoever additional voltmeter-testing totally useless. If the weather is cold or your battery is old, your battery could be the upshot and your alternator might be just fine. That's why you need to cheque the bombardment before checking the alternator.^[iii] Here'southward how to exercise it:

   • Turn off the motorcar. You'll want to make sure your engine is off earlier attaching the voltmeter.^[4]
   • Open the hood.
   • Connect the voltmeter to the battery. Place the red atomic number 82 of the voltmeter to the positive battery terminal and the black lead to the negative concluding. Avoid touching your skin to the battery.
   • Read the voltmeter. If the battery reads above 12.2 volts, it has plenty juice to get-go the alternator, which can then exist tested with the voltmeter.
   • If the battery doesn't have plenty voltage, either get the battery charged and re-test or try a dissimilar method for checking the alternator.

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   Commencement the vehicle and rev the engine to two,000 RPM. This will draw power on your battery, which should cause your voltage regulator to kick the alternator into high gear.

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   Keep the engine running and retest the bombardment with the voltmeter. When you read the voltmeter this time, the voltage should become up to at least 13. If varying the RPMs causes the voltage to fluctuate between 13 and 14.five volts, your alternator is in adept shape; if, on the other hand, the voltage remains the same or decreases, your alternator isn't working properly.^{[five] [vi]}

   • Repeat the process with the lights, radio, and Air conditioning on. The alternator is charging if the battery voltage stays above 13 volts with the engine at ii,000 rpm and all accessories on.

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1. i

   Check the alternator gauge. If y'all take a volt/amp gauge, it will read the alternator output for you. Run engine at two,000 rpms for tests and turn on the blower fan for the AC or Heater, the headlamps, and any other accessories that put a strain on the alternator, and watch the gauge to see if it decreases voltage or amperage. Every bit a rule, if the voltmeter is college when the engine is running than when the engine is not, you tin confidently assume that the alternator is charging.

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   Listen to the alternator while the engine is running. If at that place is a problem with the bearings yous may hear a squealing sound coming from the forepart of the car, which becomes louder with more electrical accessories using ability at the same time.^[7]

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   Plough the radio on and rev the engine. Tune your radio to a low number on the AM band with no music. If the radio whines or goes fuzzy whenever you striking the gas, the alternator is quite likely the culprit.^[8]

4. 4

   Find an auto-parts store that tests alternators for gratis. Since every store would love for you to buy your new alternator from them, many will try to get the edge-up on their competitors past offering gratis testing. Dismount your alternator and bring information technology in to be sure.^[9]

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VideoRead Video Transcript

• When it is very cold outside, before you start your machine, Plow on your headlights for a min or 2, and turn it off again. A warm battery will always starting time a cold car.

• Fifty-fifty if y'all conclude the alternator is not working, the trouble may originate elsewhere. You may have a diddled fuse, a bad relay, wiring, or a lacking voltage regulator, for example.

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• Some people recommend testing the alternator by starting the car, loosening the negative battery cable, and waiting to see whether or not the engine dies. Do not attempt this method; information technology can fry the voltage regulator, the alternator, and/or the electrical components.

• Continue hands, loose clothing, long hair and jewelry abroad from moving parts when checking under the hood of the car with the engine running.

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Article Summary Ten

The alternator in your automobile is responsible for recharging your car's battery and powering the electrical system. If your headlights aren't equally bright as they usually are, your car's electric system isn't working properly, or yous're having problem starting your car, those could all be signs that your alternator isn't working properly. Fortunately, you can easily test your auto's alternator to see if it's working using a voltmeter, which is an instrument that measures voltage. Before you examination the alternator, you'll need to make certain your car'due south battery is fully charged. Turn your auto off, pop the hood, and connect the voltmeter's positive probe to the positive terminal on the battery and the negative probe to the negative terminal on the bombardment. And then, check the reading on the voltmeter. If it'due south less than 12.ii, you'll need to charge your battery before you can test the alternator. Otherwise, have a helper start your car and rev the engine to 1500 RPM. Bank check the reading on the voltmeter again. The voltage should increase by between 0.5 and two volts to around 13.vi to fifteen.viii. If the reading stays the same or drops, that means the alternator isn't charging and you may need a new one. If the reading is more than 2 volts higher, that could mean that your alternator is overcharging. Either manner, take your auto to an auto repair store to observe out what's wrong. To learn how to diagnose an alternator trouble by checking the gauge or by sound, keep reading!

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