# 2003 Volkswagen Jetta - Alternator **URL:** \ **Category:** Maintenance/Repairs\ **Tags:** volkswagen\ **Created:** [July 24, 2019, 6:08pm UTC](https://community.cartalk.com/t/2003-volkswagen-jetta-alternator/145168 "2019-07-24T18:08:03Z")\ **Posts on this page:** 11\ **Page:** 1
**Author:** ![DawnMarieClark](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/dawnmarieclark/32/16859_2.png) [@DawnMarieClark](https://community.cartalk.com/u/DawnMarieClark)\ **Post date:** [July 24, 2019, 6:08pm UTC](https://community.cartalk.com/t/2003-volkswagen-jetta-alternator/145168/1 "2019-07-24T18:08:03Z")
How do I determine if the alternator is bad on my 2003 Jetta? ---
**Author:** ![tcmichnorth](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tcmichnorth/32/25126_2.png) [@tcmichnorth](https://community.cartalk.com/u/tcmichnorth)\ **Post date:** [July 24, 2019, 6:37pm UTC](https://community.cartalk.com/t/2003-volkswagen-jetta-alternator/145168/2 "2019-07-24T18:37:33Z")
With a voltmeter, check voltage at battery when car is running. Should be 13.5 - 14.5 volts DC. ---
**Author:** ![VOLVO-V70](https://avatars.discourse-cdn.com/v4/letter/v/8e8cbc/32.png) [@VOLVO-V70](https://community.cartalk.com/u/VOLVO-V70)\ **Post date:** [July 24, 2019, 7:47pm UTC](https://community.cartalk.com/t/2003-volkswagen-jetta-alternator/145168/3 "2019-07-24T19:47:43Z")
Call your local Auto Zone if you are in the US and see if they will check it . If it is bad then you are running on the battery only and you cannot go far that way. ---
**Author:** ![DawnMarieClark](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/dawnmarieclark/32/16859_2.png) [@DawnMarieClark](https://community.cartalk.com/u/DawnMarieClark)\ **Post date:** [July 24, 2019, 8:15pm UTC](https://community.cartalk.com/t/2003-volkswagen-jetta-alternator/145168/4 "2019-07-24T20:15:20Z")
Yah. That is what I am going to do. It’s at 12.66 with the engine NOT running, which is just right. Thx for that. I hope that that is what it is … Thanks for the quick reply tcmichnorth! ---
**Author:** ![DawnMarieClark](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/dawnmarieclark/32/16859_2.png) [@DawnMarieClark](https://community.cartalk.com/u/DawnMarieClark)\ **Post date:** [July 24, 2019, 8:18pm UTC](https://community.cartalk.com/t/2003-volkswagen-jetta-alternator/145168/5 "2019-07-24T20:18:24Z")
Yah. I already did. They ran a test and it read that the voltage regulator was failing. They are not always correct so I am going to do the voltmeter test. The thing is that I live in a small town and don’t put many miles on the car, so the battery may just need a good charge. Thanks for the quick reply VOLVO\_V70. ---
**Author:** ![Mustangman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/mustangman/32/44130_2.png) [@Mustangman](https://community.cartalk.com/u/Mustangman)\ **Post date:** [July 24, 2019, 11:42pm UTC](https://community.cartalk.com/t/2003-volkswagen-jetta-alternator/145168/6 "2019-07-24T23:42:50Z")
> [@DawnMarieClark](#): > > so the battery > > may just need a good charge Not if it reading 12.66 volts, it doesn’t. That is a charged battery. ---
**Author:** ![DawnMarieClark](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/dawnmarieclark/32/16859_2.png) [@DawnMarieClark](https://community.cartalk.com/u/DawnMarieClark)\ **Post date:** [July 26, 2019, 1:27pm UTC](https://community.cartalk.com/t/2003-volkswagen-jetta-alternator/145168/7 "2019-07-26T13:27:17Z")
Thx. I tested with a 12V meter, although I read it supposed to be a 20V? Anyway it came out at 12.06 not running and 13.89 running. ---
**Author:** ![Mustangman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/mustangman/32/44130_2.png) [@Mustangman](https://community.cartalk.com/u/Mustangman)\ **Post date:** [July 26, 2019, 1:37pm UTC](https://community.cartalk.com/t/2003-volkswagen-jetta-alternator/145168/8 "2019-07-26T13:37:25Z")
12.06V means the battery needs a charge. 13.89V running is OK, and low-normal, probably because the alternator is working hard charging the battery. Nothing should be 20V. ---
**Author:** ![DawnMarieClark](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/dawnmarieclark/32/16859_2.png) [@DawnMarieClark](https://community.cartalk.com/u/DawnMarieClark)\ **Post date:** [July 26, 2019, 1:57pm UTC](https://community.cartalk.com/t/2003-volkswagen-jetta-alternator/145168/9 "2019-07-26T13:57:34Z")
The 20V came from a post on Advance Auto Parts site. AAP is where the alternator was purchased in 2013. First read at AutoZone was “failing voltage regulator.” So I went to local NAPA to see what it would read and it was 12.66. Last nite at home with a 12V it was 12.06 So it looks hopeful that the alternator is ok and that I need to charge the battery because it’s short local driving and the battery does not get fully charged? ---
**Author:** ![pyrolord314](https://avatars.discourse-cdn.com/v4/letter/p/6a8cbe/32.png) [@pyrolord314](https://community.cartalk.com/u/pyrolord314)\ **Post date:** [July 26, 2019, 2:21pm UTC](https://community.cartalk.com/t/2003-volkswagen-jetta-alternator/145168/10 "2019-07-26T14:21:58Z")
> [@DawnMarieClark](#): > > The 20V came from a post on Advance Auto Parts site. AAP is where the alternator was purchased in 2013. 20V?! 🤦‍♂️ Maybe they meant to set your voltmeter to read up to 20V? That would make sense if you have one that could read either 10 or 20 Volts… > [@DawnMarieClark](#): > > So it looks hopeful that the alternator is ok and that I need to charge the battery because > it’s short local driving and the battery does not get fully charged? Yes, I would agree with that. ---
**Author:** ![DawnMarieClark](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/dawnmarieclark/32/16859_2.png) [@DawnMarieClark](https://community.cartalk.com/u/DawnMarieClark)\ **Post date:** [July 26, 2019, 2:32pm UTC](https://community.cartalk.com/t/2003-volkswagen-jetta-alternator/145168/11 "2019-07-26T14:32:37Z")
Yes, it read to set it to 20V on AAP site. Sorry for not being clear on that. 🙂 Last nite we set it to 12V, which was the highest voltage and we got the 12.06. So I am happy that I just may not need a new alternator. Thx