Alternator not charging?

KHANTALHA

MEMBER
2012 HYUNDAI ACCENT
1.6L
AUTOMATIC
117,000 MILES

Hi,

I have the vehicle listed above hatchback. A couple of days ago I had the MGP meter reset when I started the car, and it was normal after that. I changed the driver power window control switches by myself through an aftermarket replacement from Amazon. Everything was working just fine for 2 weeks. Couple of days ago I started the car and my trip meter, e/t, MPG reset all by itself again. I ignored it for a few minutes, and I started driving. I noticed that my audio head unit kept turning on and off particularly when I accelerated, so I decided to head to AutoZone and get my battery checked. They said that the battery was at 44% charge and it’s a good battery, but the alternator was not charging. I immediately got an aftermarket alternator from Amazon and replaced it myself. Initially after replacing the alternator everything started working fine even though I had everything reset again and the audio head unit shut down a couple of times, but it worked perfectly fine as I ran the car for 50 miles without any hiccups. The next day when I started the car the audio unit kept restarting again, this time with more frequency and even shut off when idling at times.
I got my car battery and alternator checked again at Oreilleys this time and they said Alternator and Battery was in good condition and need no replacement. I checked all the fuses in the fuse box in the cabin and in the engine hood, but everything is fine. Oreilleys said just get the car computer reset at the dealership but I’m not sure if this would help either.
however, I would like to mention that I got the car oil serviced at Hyundai a month before this started.
Please help as I’m not able to diagnose this issue at all.

1 Reply

AL514

MECHANIC
4,781 POSTS

Hello, on most modern vehicles the ECM (engine computer) needs to know there is a new battery installed, doing a reset procedure or sometimes called a battery registration lets the ECM know there is a new battery or an over charging condition may occur and it will ruin the new battery. Another note is when it comes to major electronic parts such as an Alternator, that is not something you want to buy off of amazon. Charging systems these days, or even a 2012 are much more advanced than people may know. Buying an Alternator from amazon might be cheaper to begin with, but it long run you will run into issues like this, and you dont want a charging system to damage the ECM which looks to be located on top of the battery in this vehicle.

The battery reset or registration needs to be done with a capable scantool, not a basic code reader. But the problems you are now having with things shutting off and turning back on themselves, I would be suspicious of that alternator possibly putting out AC voltage due to some faulty diodes inside. But either way you may want to bring it to a shop that can do a battery reset and check the charging system, before it starts burning out control modules..

I dont think this has anything to do with the oil service, the vehicle is designed to run on DC voltage only, and when the alternator diodes start to fail it will start to put out too much AC voltage and one by one modules will start to fail, and that will get expensive real fast. So bringing it to a decent shop or dealership is not a bad idea.
If youre concerned about their service, look them up online and read some reviews of the shop. And you can always post back on here what they found, if trouble codes are stored in other modules, or anything else they find and we can look up service info for you ,.

https://www.2carpros.com/articles/how-to-check-a-car-alternator

https://www.2carpros.com/articles/how-to-replace-a-car-battery