Autozone alternator test wrong

Many times an alternator is not working properly because of poor electrical connections in the charging circuit. Loose or corroded connections on the back of the unit can increase resistance and restrict the current flowing through the circuit. The same goes for broken or frayed wires inside a connector or the alternator wiring harness. So save yourself the embarrassment and hassle of a comeback and test the alternator wiring connectors and wiring harness.

To perform a voltage drop test, set the voltmeter on the 2-volt scale and touch the positive and negative test leads on opposite sides of a connection. If there is resistance in the connection, some of the voltage will try to bypass the resistance by flowing through the voltmeter.

A reading of more than 0. Ideally, the voltage drop across any connection should be zero or less than 0. Poor ground connections are an often-overlooked cause of low charging output and alternator failure.

Voltage drops on the negative side can cause overcharging. Voltage drops on the positive side of the charging circuit can cause undercharging. When a new alternator is installed, check the battery voltage and use a battery charger to bring the battery up to full charge before you return the vehicle to your customer. Also, start the engine and use your DVOM to check the charging output of the alternator.

The starter plays an unusually important role in the modern computerized engine management system because most late-model engines must crank at about rpm to activate the electronic fuel injection. Without seeing a reliable CKP signal to indicate sufficient cranking speed, the PCM may not activate the fuel pump relay, thereby creating a cranking, no-start condition.

In the same sense, many vehicles equipped with airflow sensors or meters must also generate a specific volume of airflow through the meter to close the fuel pump relay. In either case, if the starter fails to spin the engine fast enough for the PCM to activate the fuel pump, the engine will not start. The answer will be relatively obvious on low-mileage vehicles that have little wear on the battery, starter or charging and engine management systems.

There are many things to take into consideration when diagnosing a starter failure. Here is a one-of-a-kind, easy to use, online diagnostic tool for even the most difficult rotating electric diagnoses. Understanding battery ratings and charging procedures is a big part in the testing of a faulty battery. Related Information.

Can you bench test an alternator?

Read More. Testing Automotive Batteries and Starters Understanding battery ratings and charging procedures is a big part in the testing of a faulty battery.

Quality Brands. Send this to friend Your email Recipient email Send Cancel.Went got a test from autozone for my alternator! When she ran the test she stated everything us normal bur read battery voltage is too low! What does that mean? Do ii need a new battery or alternator? This could mean the alternator is not charging the battery high enough or the battery will not accept and hold a charge.

You may need to replace the battery first, then recheck the alternator charging system for proper operation. If you need help, an expert from YourMechanic can come to your home or office to inspect why your battery does not hold a charge and replace the alternator if necessary. Q: Went got a test at Autozone for alternator, she stated everything test normal but battery voltage is too low? My car has miles.

My car's transmission is unknown to me. Jay Safford Automotive Mechanic. The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details. Home Questions. What others are asking Turbo losing power If the Turbo bearing is starting to go bad then the turbo may be noisy.

The turbo could need to be inspected for fin damage or a binding waste gate operation. Also, the intake tubes would need to be checked Read more. Starter, alternator, or battery?

Bad alternator? Autozone messing with my confidence...

Hi there. In most cases, when you're pulling less than 15 volts from the alternator the issue is caused by an internal component failure within the alternator itself or the alternator relay.

If the starter is not receiving the correct When doing a radiator flush - do you need to replace the thermostat or any other components of the cooling system Doing a radiator flush does not require any other component to be replaced. However, if the system has a lot of debris and scale in it, the thermostat may need to be replaced if it gets clogged or corroded. Something rattling inside car door Hello.

The rattling noise you are hearing in the door is probably due to a nut or bolt that has come loose and has fallen to the bottom of the door. With a power window regulator, the window glass and Shifter stuck in park The Problem with your car is the shift interlock release latch is broken and is a common problem with these cars. The interlock release is located under the shifter and can be replaced fairly easily with a new metal part Had gas pedal assembly and throttle replaced.

Wire harness or computer n This vehicle may have a wire harness issue of bad crimps on the connectors to the cluster, engine control module ECMand other areas that can cause these intermittent failures.

The codes you are receiving are most likely the As you know, these have electric motors in them that wear out over time and will begin to make squeaking or grinding noises as the bearings begin to wear out.

Test Alternators Before You Replace Them

How do the rod bearings stay in place? All the engine main and rod bearings along with the balance shaft bearings will have a small index on one end of the bearing. You should see a slot for the new bearing to line up and go in only Vehicle feels as if it is dragging or pulling something.

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2003-2004 Silverado/Tahoe alternator testing - test the turn on wire

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autozone alternator test wrong

Thread starter TheUser Start date Feb 18, JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding. You are using an out of date browser. It may not display this or other websites correctly.

You should upgrade or use an alternative browser. TheUser Active Member. Jul 25, 1, 0 36 36 Springfield, MO Visit site. Sold the car for salvage and kept some parts off of it to resell.

I drove the car a total of about 4 miles before it broke, but I do not remember the battery light coming on. I have no reason to believe the alternator is bad, but wanted to have it tested before I sell it.

I've went to 2 autozone stores and it fails at both of them two times at one store and one time at another. I've went to 2 O'Reilly Auto Parts stores and it passes at both of them. I mentioned this to the guy at the last Autozone store and he made a comment that the machines are the same exact machine and made it sound like I was lying to him.

Not trying to start anything, just wondering why the stores would differ and is there another way I can test it? I don't want to sell a bad alternator, but I don't want to junk a good one either. LarsD Founding Member. Jul 2, 2, Texas Visit site. Only answer I can think of is to bolt it up to a car and see the output it makes. Shiroelex There's nothing worse than aut Founding Member. Aug 23, 1 27 38 Westland, MI.I took my Jeep Cherokee to Autozone auto parts store to have the alternator tested.

I am suspicious that it just overcharged and ruined my last battery.

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The guy at Autozone said I would need to remove the alternator to have it tested. Oh man, is this really necessary? Is there no way to verify whether or not its overcharging with it still in my car? You need to remove it to have it tested with their type of test equipment.

This is actually a very marginal test. The diode bridge in the alternator can become defective in a way that allows perfect voltage at normal load conditions, but fails under heavy load headlights and AC on. When the parts store test the alternator, they test it under load. But you can apply that substantial load by turning all he accessories on including heater, lights, radio, etc. The standard procedure for on-car alternator testing includes measuring the charging voltage at idle with headlights on and blower on high.

Those two items are considered to provide sufficient load. With the car off, a charged battery should read about With the car running, the voltage should read Check the voltages with the car off, and running with little electrical load and with a lot of load ie.

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Do I really need to remove my alternator to have it properly tested? General Questions.This company is not yet accredited. See reviews below to learn more or submit your own review. Thank you, you have successfully subscribed to our newsletter! Enjoy reading our tips and recommendations. A link has directed you to this review. Its location on this page may change next time you visit. For more information about reviews on ConsumerAffairs. They changed it out for me, quickly— even going out to their delivery truck to get one not yet unloaded.

Their more experienced mechanic came out to take a look at it and noticed the terminal wires were in bad shape. Because over the course of my visit, they learned that I am currently unemployed, they installed new terminal wire at no additional charge!!!

While sitting on the curb writing this review, another AZ gentleman came over and asked me if I wanted a chair. Soooooo NICE!!???

I looked up one at Autozone and one at Orylies auto parts. I spoke with this very polite young man. Do not remember his name but he was very polite and he said that it would be no problem to get the hose we needed and match the price with Oriylies.

I would like to say store was very well organized for our saftey during the COVID epidemic and the customer service was great. Get buying tips about Auto Service and Repair delivered to your inbox. On march 12th, I had my batt light come on, in my dooly, we were 11 hrs away from home. The alternator I had on there, was only 2 wks old. I was so fortunate to have stopped at this autozone, they went way above the bar in helping me, due to them, we made it home safely, thanks again to jorge, vicky and aron.

Then on a very cold and windy day, he came out to replace the bulb that required him to remove the battery. He asked me if I have the code to start the radio back. Then he replaced the bulb with latex gloves, added special gel and replaced the bulbs and placed the battery back. All this with a smile and a very pleasant attitude. When I asked what kind of coffee he drinks, he declined to mention! Why would I go to any other auto parts place? Not to the dealer for sure! I needed parts looked up for my VW Passat.Click to see full answer Correspondingly, how do you check an alternator with a multimeter?

To check an alternatorpop your vehicle's hood and hook up a voltmeter to the car's battery by connecting the red lead to the positive terminal and the black lead to the negative terminal.

Make sure the voltmeter reads at least Likewise, what causes an alternator to fail?

autozone alternator test wrong

Bad diodes are a common cause of alternator failure. The diodes are part of the rectifier assembly that converts the alternator's AC output to DC. A leaky diode also can allow current to drain out of the battery through the alternator when the vehicle is not being driven. The only way to know if an alternator is good or bad is to bench test it on an alternator test stand.

Charging output can be tested on a vehicle with a digital voltmeter. If an alternator can produce normal voltage and current during a bench testthe problem is not the alternator but something else on the vehicle.

Signs of a bad voltage regulator in a vehicle include dimming or pulsing lights or a dead battery. If you have electrical equipment that won't turn on, that could also indicate a bad voltage regulator —the regulator could either be letting no power through or letting through too much and damaging the other components. A car alternator needs to be putting out at least 14 volts ideally between Poor ground connections are an often-overlooked cause of low charging output and alternator failure.

Voltage drops on the negative side can cause overcharging. As youngfarmer says, an alternator has a rectifier in it and they can short so the alternator becomes a high amperage dead short from the main output wire to ground. Take that wire off watch out, it is hot all the time unless you disconnect the batteries! A bad ground shouldn't overcharge a battery- but if you want to verify condition of alternator and put this out of the way for the test- hook a jumper cable from neg battery terminal to alternator mount or alt.

A 12 volt battery in most cars will run about 30 minutes to 1 hour without lights or air conditioner, since many components will run than old cars before. Starting a car takes a lot of power. You should buy a battery with more power or fix your alternator. AutoZone will test your car's parts for free. We can also give your car a complete starting and charging systems test.

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You can also take your alternatorstarter or battery into our store and we' ll test it. If you're hearing a grinding sound in your car, this could indicate that the alternator is going bad. The grinding sound may be caused by a worn-out bearing. If you hear any type of whining or grinding sound that's a good indication that your alternator needs to be checked.

How to clean your alternators. Do not use petroleum based engine degreasers to clean the alternator.

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Do not use compressed air or a pressure washer to clean the alternator. Do not spray a cleaning agent or degreaser directly into any air inlet openings on the alternator.

autozone alternator test wrong

First, check the dashboard battery gauge. The battery should be giving a charge, even while the vehicle is off.

If the dashboard lights are dim, something is likely wrong with your battery. Try turning on your windshield wipers, lights or automatic windows. Typically, one of two problems cause overcharging alternators : poor battery condition and failed regulators. And a failed regulator — or a failing rotor on the regulator — may trigger an overcharging alternator because the regulator cannot correctly read the electricity level in the battery. The test will help you determine if you need a new battery, or if you vehicle has another electrical problem, such as a bad alternator.

We can test your battery, starter or alternator on or off the vehicle.The first I put inthe second April and now the third June No problem with the life time warrenty,but this alternator is not easy to put in and take out.

Where they rebuild them they need to chage everything out,not just doing what needs to be done. This is my last time I will change this out.

I will demand my money back next time. This will be the last alternator I'll buy there. Location: Madison, Wisconsin. Review is a subjective opinion of PissedConsumer This feature is currently under development. To learn more about the ways to appreciate the reviewer please visit www. Im getting their duralast gold ones. Well this last one started overcharging. Blew out my headlights.

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Ive already contacted my insurance and filing a claim at noon when the manager gets in today. I should mention im a shop owner and mechanic so not only am i pissed about my Lexus, they have officially lost a commercial account. I have just had this same issue with the Alternator in my Trailblazer bought one from Auto Zone end of June and had to replace it again first week of October.

Seemed to be an intermittent problem with the voltage regulator part of the alternator. Took me about an hour and a half to replace, lost three hours of work though. My friend was having this issue with his Toyota Camry, had to replace his alternator about once a year. As I see it, whoever came up with putting the voltage regulator inside the alt.

Chrysler, and most other manufacturers for years mounted the voltage regulator on the firewall, making it easier to change.

This is the part that most of the time seems to be the failure, but, you cannot just get the voltage regulator, you have to buy the entire alt. The one I just changed was a bit over a year old. They need to re-evaluate the failures, and work to improve the quality of the product. My original alt. Here's my advice after reading reviews on rebuilt alternators. Now why would you want a rebuilt anything for just that difference. After all, when you are stranded, and that is all that is available, that is what you have to go with.

In my case, there were no new ones, except OEM, and that would take days to get.


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