Battery not getting charged

Tiny
MR. BAD LUCK
  • MEMBER
  • 1998 FORD EXPEDITION
  • 5.4L
  • V8
  • 4WD
  • AUTOMATIC
  • 80,000 MILES
Hey everyone. Okay, I have the vehicle listed above I have had it for about two months it’s been running good until a few weeks ago I came home about 8:30 it was dark I noticed my lights started going dim until they went off. As I pulled in the driveway put it in park my truck shut off. Replace alternator and charge the battery started right up but after a few minutes shut off. So I got my multimeter check my battery was at about 9.90v. I jumped it again and started it pulled off the cables checking my battery again with the multimeter I can see it slowly decreasing in voltage so I try to excite the alternator by ripping it up to about 2,000 to 2,500 RPMs but instead of charging the battery I saw it using up more the voltage faster got my multimeter went to the alternator. Checked to see how many volts I was pushing was at 12.5 nothing more nothing less but wasn’t charging the alternator. I looked it up said I should be pushing out 13 1/2 to 14 V coming out of the alternator with vehicle on so I went to replace it. But this time I figured maybe my battery was going out so I replace the battery and replaced the alternator again and still no charge. The battery stays on when I got the new battery for a good 15-20 minutes. Still decreasing in voltage the whole time trade exciting the alternator again by revving it up and still not charging. Alternator is not charging. Check the fuses make a fuse I don’t know what else to do. If anyone can help I greatly appreciate it. Thank you!

P.S: My back up vehicle Mazda Tribute 02 it’s starting to do the exact same thing. Someone please help!
Friday, June 11th, 2021 AT 9:06 PM

20 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,407 POSTS
Hi,

For the alternator to produce a charge, it needs power. There are two fuses I need you to check. First, there is a mega fuse (175 amp) under the hood on the driver's side near the rear of the engine compartment.

Next, there is a 20 amp inline fuse that is near the alternator that needs to be checked.

I attached the wiring schematic for the charging system. I highlighted the fuses to check. When you check the fuses, confirm there is power to and from it.

Here is a link you may find helpful:

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

Let me know what you find or if you have other questions.

Take care,

Joe

See pics below.
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Friday, June 11th, 2021 AT 11:12 PM
Tiny
MR. BAD LUCK
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Joe. Hi and thank you for responding. Yes, I’ve checked and replaced both even though they were good.
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Saturday, June 12th, 2021 AT 8:41 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Hi,

Are you getting power to the orange/light blue and the yellow/white wire at the alternator? If you are, something is wrong with the alternator. If you are not getting power, go back to the fuses and confirm there is power to and from them. Here is a link showing how that is done:

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

Let me know.

Joe
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Saturday, June 12th, 2021 AT 8:49 PM
Tiny
MR. BAD LUCK
  • MEMBER
  • 11 POSTS
The colors on mine r Gn/r And o/w. O/w I believe is the dash and yes the Gn/r goes to the PCM. I did notice today the Gn/r From the alternator it goes to right behind the mega fuse and it’s a connector from the alternator to the mega fuse it ends at a male. I had continuity from there to there but from the female part to the PCM I wasn’t getting any kind of continuity so as of power on the green/red I don’t think so from the plug. So I cut the wire and connected them without the connector still nothing. Which is weird because I had power from the alternator two the male end.
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Saturday, June 12th, 2021 AT 9:22 PM
Tiny
MR. BAD LUCK
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  • 11 POSTS
Joe, fuses are good, double checked every fuse except for relays and diodes. Not sure how to check them other than switching them with like relay/diode.
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Sunday, June 13th, 2021 AT 4:11 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,407 POSTS
Which wire are you not getting power to? The orange/light blue and the yellow/white must have power at the alternator. Are those wires a different color on your vehicle?

As far as the starter relay, power doesn't go through the relay for the alternator. It is a splice location, so the condition of the relay doesn't play a role.

As far as a diode, it is internal and is used to change an AC current into a DC current and it limits the direction of power flow in one direction. I don't think that is an issue either.

If there is a relay you would like to check, here is a link that shows how it is done:

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Let me know about the power supply to the alternator via the wires I mentioned above. Also, if there isn't power, recheck for power at both ends of the fuses.

Don't worry, we'll get it figured out.

Take care,

Joe
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Sunday, June 13th, 2021 AT 7:26 PM
Tiny
MR. BAD LUCK
  • MEMBER
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I posted some pictures (I hope you can see and understand them ) it is an o/blk from alternator to a fuse right under the mega fuse and g/y from alternator to connector and connector to the power control module. Connector to PCM no continuity but (not power) from connector to alternator have continuity (not power) could it be from the connector to the PCM I may have a break in the line where it’s not sending or receiving power through it? But I do have power to the alternator it’s only pushing 12.5 V with the truck on... I want to just thank you for taking the time and trying to help me figure this out I am very grateful and appreciative!
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Sunday, June 13th, 2021 AT 10:22 PM
Tiny
JACOBANDNICKOLAS
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Hi,

Is there power at this wire? See pic below. Also, there appears to be a connector (something black) on the wire. Check for power on both sides. Also, the light green which should have a red tracer goes to the instrument panel for an indication of a no charge.

I'm not sure why the wire colors are different on your vehicle. Do me a favor. If you open the driver's door, there should be a label with a manufactured date. Let me know what that date is. I may have to go back or ahead a year if it is an early or late production vehicle.

Let me know.

Joe
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Monday, June 14th, 2021 AT 7:46 PM
Tiny
MR. BAD LUCK
  • MEMBER
  • 11 POSTS
I will check for the power first thing in the morning. It’s a 1998 the door is from a different Ford from previous owner. VIN says it’s a 1998. It’s a 98 Ford Expedition Eddie Bauer 4x4 5.4. Yes, there is a lot of different things on this compared to my 1999 Expedition Eddie Bauer that’s in the shop.
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Tuesday, June 15th, 2021 AT 12:37 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Let me know what you find. Also, if you look at the schematic I sent, I need to confirm there is power to the yellow wire with a white tracer.

One last thing, the last pic you attached has a green wire with electrical tape on it. Make sure there isn't a problem at that point.

Take care,

Joe
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Tuesday, June 15th, 2021 AT 8:41 PM
Tiny
MR. BAD LUCK
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I don’t see a yellow wire with white tracer.
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Wednesday, June 16th, 2021 AT 2:04 AM
Tiny
JACOBANDNICKOLAS
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Hi,

I'm wondering if something was changed. The inline fuse is in the yellow/white wire. It should be there.

If you look below, I attached the wiring schematic from the manufacturer. It shows it.

Let me know.

Joe
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Wednesday, June 16th, 2021 AT 8:11 PM
Tiny
MR. BAD LUCK
  • MEMBER
  • 11 POSTS
Everything seems to have power but the alternator is pushing only 9-10 volts.
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Friday, June 18th, 2021 AT 4:07 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Hi,

If there is power to the alternator and it's only producing 9-10v, it sounds like it's bad. At this point, I would remove it and have it bench tested at a parts store.

Here is a link that shows in general how it's done:

https://www.2carpros.com/articles/how-to-replace-an-alternator

If you look at the attached pics below, they are the directions specific to your vehicle.

Let me know what you find.

Joe
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Friday, June 18th, 2021 AT 6:33 PM
Tiny
MR. BAD LUCK
  • MEMBER
  • 11 POSTS
Okay, thank you! So even though this is the 2nd one? After I replaced the one when this all started then that one was putting out only 12.5 v with truck on and was not getting excited to charge the battery.
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Friday, June 18th, 2021 AT 10:33 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Hi,

If the wiring to the alternator is good, it is getting power, and there are no open circuits, that is what I suspect is the problem.

Remove it and have it bench tested at a parts store. If it fails, request a different brand if this is the same as the other new one you installed.

If you can, let me know what is found. I'm interested in knowing.

Take care of yourself,

Joe
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Saturday, June 19th, 2021 AT 7:46 PM
Tiny
MR. BAD LUCK
  • MEMBER
  • 11 POSTS
Hi, sorry I had a family emergency I was out of town. I took it in still the same thing it passed on there tester.
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Friday, June 25th, 2021 AT 3:50 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Hi,

We are missing something simple. I know it. For sure, the two wires I mentioned, in the beginning, are getting power at the alternator? Is there any change in voltage when the vehicle is started?

Joe
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Friday, June 25th, 2021 AT 7:46 PM
Tiny
MR. BAD LUCK
  • MEMBER
  • 11 POSTS
Yes, it will start off about 12.7 down to as low as 10v.
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Saturday, June 26th, 2021 AT 2:41 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,407 POSTS
Is the 12.7v also there when the engine isn't running? I'm just trying to determine if that is simply battery voltage. I'm sorry for so many questions. This just isn't making sense. If you have power to the alternator and it is good, it should be producing a charge.

I'm wondering if there is something I'm missing because of the difference in wiring color. Or, is the alternator the same as the one you removed? Maybe they gave you the wrong type.

Let me know.

Joe
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Saturday, June 26th, 2021 AT 7:25 PM

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