When you have an electrical problem in your vehicle there are usually two main causes that you're going to want to look into. Your battery and your alternator. If your battery is working fine, then your alternator is the likely source of a problem that you are experiencing. If you've tested your alternator out and determined that it is the cause of the problems you're having, then you're going to have to get it replaced which doesn't necessarily have to be the most complicated job in the world, but it will take some time. Replacing an alternator can take up to about two hours or so at a mechanic but could take longer if you opt to get the job done yourself and you’re new to this kind of a repair.
What Does Your Alternator Do?
While it seems like the battery in your car is solely responsible for keeping all the electronics working it's not actually the case. The battery is basically what gets everything started but the alternator is what keeps it running. An alternator is essentially a generator and it actually keeps the battery in your car charged while it's running. It also supplies electric power to keep the other electrical systems in your vehicle, things like your heater or air conditioner, the radio and lights, power windows and doors, working.
For the most part an alternator doesn't require any kind of maintenance. It should be able to do its job problem-free for at least 10 or 15 years. Of course, nothing is guaranteed and depending on any number of factors your alternator could end up dying on you sooner rather than later. If that's the case, you're going to need to have your alternator replaced because your car can’t function for very long with a faulty alternator.
How Much Does It Cost to Replace an Alternator?
If your alternator has failed completely and you need to get a new one, the cost of getting it replaced at a mechanic can be fairly steep. Replacing an alternator is likely to cost you anywhere between $300 and $1,000 depending on the make and model of the car that you drive. You also have the option of getting a remanufactured alternator, which is to say one that actually has been used before but has been refurbished to like new condition. These alternators cost around $300 to $500 to replace including the cost of labor.
If you plan on doing the repair job yourself then you can head to AutoZone and check out new alternators which can cost a range of prices but can be as cheap as $90 or so brand new. Obviously if you're heading this route, you're saving a considerable amount of money to replace the alternator yourself.
Signs and Symptoms of a Bad Alternator
There are a handful of signs and symptoms you can be on the lookout for if your alternator is starting to fail on you to let you know that it's time to get it replaced before it dies completely. If you start experiencing one or more of these, you very likely need a new alternator.
Flickering and Dimming Headlights
When you first start your car if the headlights dim that could be an indication that you have a battery issue. However, when your car is running the alternator takes over. If your lights continue to stay dim or flicker frequently then that's a sign that your alternator is not working properly.
Warning Light on Your Dashboard
Just like your engine has an issue when the check engine light comes on, when your electrical system gives you problems you'll also get an indicator light on the dashboard. This usually has a battery shaped symbol and it may read something like ALT or GEN to let you know that there is an issue.
Because the alternator provides power to the spark plugs that are used to ignite the fuel and air mixture to allow the combustion reaction to keep your car going, if your alternator is failing then your spark plugs won't be sparking properly. That can at first cause misfires and then can end up causing straight-up engine stalls if it gets bad enough.
Your alternator provides the power for all your electronic components while the vehicle is running. If things are starting to fail on you and not work properly in the cabin of your car there’s a good chance your alternator is not working. Anything from your heater, to your air conditioner, to console lights, to the power windows could all be related to problems with your alternator if they're not working correctly. That said, if just one of those components fails while the others seem to be working fine, it's probably not your alternator but that specific component. However, if you're having an issue with all of these electronics at the same time, you can almost guarantee that your alternator is to blame.
It seems a little counterintuitive to say that a dead battery is a symptom of a bad alternator but remember that your alternator actually charges your battery. If your battery should still be functioning properly, which is to say it's not that old and should be maintaining a decent charge, then it's possible your alternator has failed at keeping it charged and that has caused it to die prematurely. It's always possible that your battery was drained for another reason, and if you have had your battery for an extended period of time at this point then it may have a different cause but if you know it should still be working then definitely give your alternator a look as the potential cause for the problem.
Can I Replace My Own Alternator?
If you want to save yourself a bit of money on labor costs you could definitely replace the alternator on your own if you are so inclined. The alternator is not too hard to replace and we would consider it something of an intermediate-level car repair. If you've done work under your hood before, maybe replacing a serpentine belt or your oil filter, then you can probably handle this job.
Step 1: We are working with the electronics in your vehicle here so the first thing you are going to want to do is disconnect your battery. You never want to touch the alternator if your battery is still connected. Make sure you disconnect the negative battery cable before you get started.
Step 2: Now you can remove the power cables from the alternator. The main power cable will probably be a larger cable that connects the alternator to the battery. This will either take a ratchet or a wrench to do depending on how much space you have available. Set the bolts aside somewhere safe so you can get back to them later.
Step 3: Remove the clip that connects the wiring harness to the alternator. This should be the only other wire that is connected to your alternator so it should be easy to find. The wiring harness is one of those clip attachments so you either need to use a flat head screwdriver to release it or if you have a bit of a fingernail you can get in there you can unplug it with that. Put the wire aside for later.
Step 4: To release the alternator you're going to need to move the serpentine belt which is arguably the hardest part of this repair job. That means you have to relieve the tension on the serpentine belt with the auto tensioner if it has one. Unfortunately, not every alternator is set up the same way and not every vehicle has a tensioner pulley. Some have a spring-loaded tensioner that you can pull back with a wrench but on others they will be rod-end type tensioner or screw type tensioner that require you to turn a bolt with a wrench or socket until the tension is released enough to remove the belt. This really depends on the kind of vehicle you have, so if you're not sure how to get that belt off, you may need to look up your specific make and model of vehicle. Once you know how to release it however, you can slip the serpentine belt off to free up the alternator.
Step 5: With the serpentine belt free you just need to remove the bolts that are connecting the alternator to the bracket. You may as well take this opportunity to inspect the serpentine belt if you have it off. Look for any wear on the belt, cracks or breaks in the rubber, or shiny spots that look like it is worn thin. If it needs to be replaced, now is the best time to do it.
Step 6: You should be able to completely remove the alternator at this point. It might take a little finesse to get it, but just take it slow and steady if you need to. This is a good opportunity to double-check that your replacement alternator is exactly the same as the one you just took out. All the mounting holes and connectors are in the exact same place so that when you put it back in, there won't be any difficulty getting it to fit. You never know if the one you bought, especially if you ordered it online or something, is going to be the exact one you need. Mistakes get made from time to time.
Step 7: Install your new alternator where the old one was making sure that you're holding your loose wires and serpentine belt out of the way until it's in place.
Step 8: Insert the mounting bolts and tighten them by hand until they are snug.
Step 9: You can install the serpentine belt now, whether it's the old one or the new one, and that may require you to check out the diagram that is located inside the engine bay of your car. It's actually a bit of a puzzle getting a serpentine belt looped in the correct position so if you don't have a diagram inside the engine bay, check your owner's manual or, if need be, Google it.
Step 10: You’ll have to use the auto tensioner pulley or use some kind of a pry bar to apply the proper tension to your belts to get it securely in place.
Step 11: Now you can securely tighten the bolts and make sure the belt has the proper tension, it should have less than an inch of play if it's on correctly.
Step 12: You can now reconnect the power cable and the wire harness the way they were before you remove them. The wiring harness should click into place when you get it in snugly.
Step 13: Now you can reconnect the battery and everything should be good to go. You just replaced your old alternator with a new one and saved yourself several hundred dollars that a mechanic would charge you for the same job.
The Bottom Line
Your battery and your alternator work together to ensure that your vehicle is able to get started and then keep running once it has started. While it's gasoline that fuels the combustion reaction it is electrical power that makes everything else in your vehicle run so your alternator is incredibly important to the life of your vehicle. Most drivers will initially blame a battery for any electrical mistakes or problems in their vehicle, but the alternator is usually the source of problems if anything goes wrong while your car is running.
Fortunately, if there is a problem with your alternator you don't necessarily have to shell out big bucks at a mechanic to get it fixed or spend a lot of time getting the job done. If you have the money to get a new alternator on your own and about two or three hours of your free time to spare replacing it, you can get your alternator fixed on your own without having to break the bank or miss out on an entire day's worth of driving like you might have to when you take it to a mechanic.