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Alternator issue

15GTCA

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So first of all i searched but did not find anything on 2015 GT charging/alternator issues. One week ago i was driving home and my gauge panel and door panel indicator lights went off. The Gauges all worked and the 2 info screens lit up but nothing else. I switched to the gauge mode and watched the volt gauge reading 12.5 volts. I drove the rest of the way home, about 10 minutes, and then shut the car off. When i restarted everything worked normal and the volt gauge showed, 13.9 volts. I have been monitoring the volt gauge every day for the past week and it has been normal 13.9 volts. Today on the way home from work, the gauge stayed at 12.5 volts but would jump up to 13 and back down to 12.5 so i detoured in to my local dealer and showed them what was happening. So they suspect maybe a bad diode in the alternator, but they will check it out tomorrow. In the mean time i am driving a Festiva,:doh: under warranty till they figure out the problem with the charging system. Has anyone else had charging system issues with their 5.0 GT's ?
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jasonstang

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Ford has this smart charging system that only charges the battery when needed to improve battery life and as well as reducing engine drag to improve efficiency.
As for why your dash light went off, do you have something on the dash blocking the light sensor?
 
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15GTCA

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No, This happened the first time in the evening when it was almost dark and the headlights were on. When i turned off the headlights everything went back to day light illumination, but when i turned on the headlights again, the indicators all went out. Then of course there is the low voltage issue if the lights are on or off does not matter.
 

jasonstang

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No, This happened the first time in the evening when it was almost dark and the headlights were on. When i turned off the headlights everything went back to day light illumination, but when i turned on the headlights again, the indicators all went out. Then of course there is the low voltage issue if the lights are on or off does not matter.
I do notice sometimes when you turn on headlights when ambient is still bright, even the highest setting of backlight is too dark.
How low is low voltage?
 

Blue Horse

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Normal CHARGING for the 12 Volt battery is, 13.8-14.2 that is what a healthy Alternator puts out.
 

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Ive noticed my car will fluctuate from about 12.3-14.6 I havent had any issues though, but I only have about 600miles on the car so far.
 

TruBlu16GT

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Ive noticed my car will fluctuate from about 12.3-14.6 I havent had any issues though, but I only have about 600miles on the car so far.
Mine does the same thing too. I noticed this on the ride home from the dealership even! Ford assured me, like was said above, this is due to the Smart Charge system. I don't think I've seen anything lower than 12.3V either. I'm old fashioned and used to seeing 14.6V constant. The fluctuations still give me the heeby-jeebies. But the Pony has been my daily ride for the last 2 months and everything works fine.

The OP's real problem is why some of his lights on his door switches went out. That might be a wiring issue.
 
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15GTCA

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Mine does the same thing too. I noticed this on the ride home from the dealership even! Ford assured me, like was said above, this is due to the Smart Charge system. I don't think I've seen anything lower than 12.3V either. I'm old fashioned and used to seeing 14.6V constant. The fluctuations still give me the heeby-jeebies. But the Pony has been my daily ride for the last 2 months and everything works fine.

The OP's real problem is why some of his lights on his door switches went out. That might be a wiring issue.
I feel the same way that you do about the charging rate. I sat in the car watching the volt gauge jump between 12.5 up to 13 down to 12.5 up to 14 down to 12.5 and so on. I am also thinking that the indicator lights are affected by the charging rate which is probably part of the battery saving feature. I have owned the car for 9 months and to this point it has been charging fine, nice and steady.
Thanks to everyone for the responses because this is the first time I have heard of this happening with the S550 model.
 

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I feel the same way that you do about the charging rate. I sat in the car watching the volt gauge jump between 12.5 up to 13 down to 12.5 up to 14 down to 12.5 and so on. I am also thinking that the indicator lights are affected by the charging rate which is probably part of the battery saving feature. I have owned the car for 9 months and to this point it has been charging fine, nice and steady.
Thanks to everyone for the responses because this is the first time I have heard of this happening with the S550 model.
My voltage reading fluctuates from 12.2v-14.2v which is very annoying
I hate when I get into the vehicle and without starting the engine the battery voltage reading on the icu is less than 12vs
I believe it should be at least 12.5v, less than 12.2 is considered a dead battery, but I havnt had any issues in the last 2 months
dealership replaced the battery last month as it was bad
 
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15GTCA

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The follow up to my issue was exactly what i expected to hear. The dealer ran a voltage charging check at the alternator and said it is charging fine. They said that it is normal for the volt gauge to fluctuate because the software will only charge when it needs it. With the responses that i have seen from some of you on this thread, I see that i am not the only one to have this happen. They have no answer for the illumination issue, of course.
Now i have been a mechanic for the last 40 years and i know that more and more software is running more systems than ever on cars and trucks. I have seen issues like this happen at my job with everything from Freightliner tractors to Ford automobiles. I don't always understand why it happens but i know that it does. I don't always like it either. So in closing i guess that i have no answer for the illumination issue. I hope that any of you who are concerned if this happens to you, should take your car in to the dealer to have it documented for future reference.
 

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Totally reviving an old thread but this completely saved me a trip to Ford while on vacation! Thanks all you guys for the information.
 

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Saved me here as well, I just put a new battery in last night, started it. Read 14.5 ish volt. Drove it today and it was sitting at 12.6 and then spiked up to 14 and back down. Freaked me out!
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