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Alternator bad?

Tiny
CHRISSTRINGS
  • MEMBER
  • 2006 FORD FOCUS
  • 103,000 MILES
I have a 2006 Ford focus. Last night it behaved as if the alternator went bad
the lights went dim, the radio said "Low Battery" and cut off. We got it home, and when I went to restart the car, the battery was dead.I jumped it, put a voltmeter to the alternator and it came out 8.6. It ran for awhile, but eventually stopped, again battery dead. Today, I disconnected the negative battery terminal as I was thinking of taking the alternator to Auto Zone to get tested, but due to its location, it was too difficult a job. So I jump started it and took it to a local mechanic, he put the voltmeter to it and it tested fine 14.2. Since the battery is over 5 yrs old, I put a new one in. Started it, put the voltmeter to it, 12.5 then after about 30 seconds or so went to 14.23 and stayed there. The only "work" I did was disconnect/reconnect battery terminals. What is going on? Can an alternator work intermittenly before it fails completely? Is there something else that should be tested? Or can this all be from a failing battery?
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Wednesday, November 30th, 2011 AT 10:59 PM

22 Replies

Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Have the computer controlled of the alternator's field generation circuit checked/tested
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Wednesday, November 30th, 2011 AT 11:03 PM
Tiny
ROBERT85
  • MEMBER
  • 11 POSTS
Computer controlled circuit for the alternator? Are you meaning the relay for the power or testing it within the ecm? Could you clarify for me Rasmataz.
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Wednesday, January 25th, 2012 AT 3:19 PM
Tiny
STEPHIERN
  • MEMBER
  • 4 POSTS
  • 2004 FORD FOCUS
  • 2.3L
  • 4 CYL
  • AUTOMATIC
  • 112,000 MILES
Hello and thank you in advance. Please help I'm at my wits end!
I purchased my 04 Ford Focus a year ago, it ran great and checked out good with a Goodyear shop. About 2 months later the key wouldn't turn. I quickly figured out if I lightly tapped it with something it would turn and started perfectly. I ordered a new key assembly and keyed it myself so that I wouldn't have to purchase new chip keys. I couldn't find anyone that would replace it for me so I kept a little hammer in my car and did that for about 4 months until I found someone. During that time, I noticed my lights started flickering and I had some power problems. When the mechanic replaced the key assembly, he also said that the alternator was going bad so he replaced it. The driving problems got better but the lights never stopped flickering. 3 months later, the driving problems (weakness, jerking) returned and I stopped at auto zone to have them check the codes if any. They tested the battery and said it's perfect but the alternator is going bad again. So I purchased my own alternator amd had a new mechanic replace it. I also bought the pigtail wires for it but returned them because the mechanic said he tested the wires and they were fine. After the 2nd alternator, it again had power and drive great- FOR 3 MONTHS. I again had it tested. Alternator bad again. After the 3rd alternator, I checked all grounding wires I could find (looked good) and I had him replace a broken purge value that we noticed. Exactly e months later, alternator bad again. Battery checking out fine. I also have turned the test mode on and it shows the battery around 13-14 while I drive. When the alternator goes bad I know it's about to act up by a constant clicking sound in the dashboard, and if I turn the car off and back on, sometimes it's fine again for the entire ride. Also during this entire time, the lights have never stopped flickering and the radio will randomly turn off/on.
Do you have any ideas as to why my alternator will only last 3 months? I've asked so many shops yo look at it and none of them want to diagnose electrical issues. Ive spent over $2000 trying to fix this and nobody hss the answer. The reason I mentioned the key issue is, could the tapping have damaged something that would cause this problem?
Any input is greatly appreciated.
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Tuesday, December 17th, 2019 AT 7:23 PM (Merged)
Tiny
CARADIODOC
  • MECHANIC
  • 33,737 POSTS
Your description of the symptoms match exactly what happens to every 1987 and newer GM product and may have the same cause. That is your perfectly fine battery. Your voltage regulator works the same way as on almost all other vehicles, but for some reason this is a major problem on GM cars and trucks. This is the first time I've heard about it on a different brand.

The issue is voltage regulators use a "switch mode" power supply similar to what's in vcrs. That allows a big current of up to three amps to be switched on and off up to 400 times per second by a little, inexpensive transistor. That current is feeding the field winding inside the generator where it makes a magnetic field, but turning off a current in a coil is exactly how an ignition coil is able to create a huge voltage spike to fire spark plugs. The field winding in your generator is doing the same thing, and every time that current is switched off, voltage spikes are produced. The battery is the key component in absorbing those spikes and is why it must never ever be disconnected while the engine is running.

As batteries age, lead flakes off the plates and it loses its ability to dampen and absorb those voltage spikes. Under testing, it may still be able to deliver its design current capacity, just not for very long. It takes time for a spike in voltage to be absorbed into the plates, and when there's less material to do that, the spikes occur and can destroy the generator's internal diodes, voltage regulator, and interfere with computer sensor signals. On GM vehicles those spikes from the generator are responsible for a lot of elusive running problems. It is also real common to go through four to six replacement generators in the life of the vehicle.

Your flickering lights are likely the result of the voltage regulator trying to keep up with the rapidly-occurring voltage spikes and trying to respond to them. This is real common on GM vehicles but it is partially due to the design of the internal parts of the generator, and they have no desire to fix it. I haven't run into this yet on Fords, but I'd at least try a new battery first before you go looking for some other cause that may not exist.
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Tuesday, December 17th, 2019 AT 7:23 PM (Merged)
Tiny
STEPHIERN
  • MEMBER
  • 4 POSTS
WoW this will be incredible if it's the answer because 1) I've asked probably 20 times 'are you sure I shouldn't replace the battery?' And 2) that is EXACTLY the code that was thrown off in the very beginning- faulty voltage regulator. I will change the battery ASAP and let you know if anything changes. If this is it I will be doubling my donation to you
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Tuesday, December 17th, 2019 AT 7:23 PM (Merged)
Tiny
STEPHIERN
  • MEMBER
  • 4 POSTS
Before I replace the battery I want to add something. Half of my dashboard lights are extremely dim. As if one side of it has a bulb out, and the only light keeping it visible is the residual light from the other half that is bright. Could an out bulb be causing this issue?
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Tuesday, December 17th, 2019 AT 7:23 PM (Merged)
Tiny
STEPHIERN
  • MEMBER
  • 4 POSTS
Okay sorry last thing. These are a few random. Things that may be related.
1) the car had obviously been in some kind of collision involving the driver side door, because the side mirror is attached a little weird like it was replaced, and I can't have the window down when opening the door or I will hear glass grinding glass like the window is misaligned in there and will break.
2) I've never had a horn. It just clicks when I push it.
3) I've checked all fuses and they appear intact and normal.
4) the symptoms are no different with the radio off or car charger unplugged, lights still flicker and engine weakness.
5) the fuel filter has been replaced.
6) SOMETIMES it won't start without me giving it a little tap of gas. But not often.
7) the stereo is an alpine and the person before me had an amp but it no longer has that
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Tuesday, December 17th, 2019 AT 7:23 PM (Merged)
Tiny
CARADIODOC
  • MECHANIC
  • 33,737 POSTS
The dash bulb is its own problem and is not related to anything else.

For the horn, the clicking you're hearing is the relay if what you're hearing is inside the car. That would be dandy news because the insane engineers at Ford have incorporated two computers in blowing the horn so normally the repair costs around $800.00. The instrument cluster is one of those computers. Since the relay is working, most likely you just have two dead horns. That can be verified by measuring the voltage at one of the horn's connectors while a helper presses the horn button. You should find 12 volts there when the button is pressed.
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Tuesday, December 17th, 2019 AT 7:23 PM (Merged)
Tiny
CARADIODOC
  • MECHANIC
  • 33,737 POSTS
Thank you for the information. The author added another dimension to the generator problem. (The "alternator" was developed by Chrysler for 1960 models and they copyrighted the term). He said the connector terminals were the cause of the problems. The story I got from a Ford trainer is they put the very high-current output wire through a pair of mating connector terminals, something no other manufacturer ever tried to do, for obvious reasons, then when they figured out little terminals can't handle that much current, they used two of them side by side to share the stress. That reduced the number of burned-up connectors, but then we were not allowed to unplug that connector, ever. Doing so would reduce their tension and lead to poor contact, some electrical resistance which translates into heat, which leads to weaker connections and more resistance, and more heat. We were told to not even remove that plug when replacing the generator. We are supposed to cut the wires. The replacement generator will come with that new connector already plugged in, and we are supposed to splice, solder, and seal the wires to the car's harness. Amazing the engineers can be so dense, but what do you expect from a group of insane designers who insist that we all want an unnecessary, unreliable, expensive computer hung onto every conceivable part of their cars.
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Tuesday, December 17th, 2019 AT 7:23 PM (Merged)
Tiny
TESS2U
  • MEMBER
  • 1 POST
Just came upon your post, not sure if the problem was ever found. But I own a 2004 focus, and it sounds like the kind of things I just started to experience. Thought rats got into wiring harness. No, nothing found. Was told I need to have the whole dash replace. Guess the focus is one known to have that problem.
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Tuesday, December 17th, 2019 AT 7:23 PM (Merged)
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 42,861 POSTS
Hello,

They replaced the voltage regulator and it looks like the problem is fixed. Do you have a battery light on?

Please let us know.

Cheers, Ken
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Tuesday, December 17th, 2019 AT 7:23 PM (Merged)
Tiny
CHRISSY98037
  • MEMBER
  • 1 POST
  • 2004 FORD FOCUS
  • 4 CYL
  • FWD
  • AUTOMATIC
  • 51,800 MILES
2004 Ford Focus SE Sedan, had its first new battery put in 6 weeks ago, then 2 weeks ago, was driving and the car full on died while driving (pardon me, I know little about car mechanics), no electricity, nothing. Had it towed to my mechanic to get it checked out. Alternator went bad, had that replaced. A week ago, go out to start my car and nothing. It's so dead I can't unlock it with my remote.

Called AAA again, they sent the same battery guy out, and he tested it and said the battery is fine so the new alternator must be no good. Called the mechanic and told him what was going on, he towed our car back to his shop, tested alternator and battery, couldn't reproduce the problem. He and his guys kept randomly starting it, and finally, one time they went out, it's completely dead again. He calls us and tells us the battery is bad.

So I've got a battery guy telling me the alternator is bad, I've got a mechanic telling me the battery is bad. So AAA sends out another battery guy to where my car is at the mechanic, he runs diagnostic and says it's not the battery and not the alternator, he suggested something about an intermittent short of some kind. My car is 7 years old, it's got just under 52,000 miles on it, and I'm hoping to not have to drop money in to diagnostics for someone to tell me it's going to cost more to replace than the car is worth.

Help please? Thanks so much!
- C in WA State
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Tuesday, December 17th, 2019 AT 7:23 PM (Merged)
Tiny
IMPALASS
  • MECHANIC
  • 3,112 POSTS
Hello â€

Sorry to hear of your problems. I will tell you right off electrical problems can be a big pain. If it quits... Then you can usually find it. Intermittent can be a nightmare.

With that... Thanks for the good description on the car.

Did you ever get this fixed yet?

If not, I am not sure where you live in Washington State, but if possible, please go to Auto Zone (AZ) or O’Reilly’s (OR) and for FREE they can pull the codes to the car. Tell them you had the engine light come on and it went off it they question it. Most important: Once they check your codes, if they find something and you don’t get it fixed and need to get back with us, please make sure you tell us exactly what the code was, number and all. Example, if the code was E0568 O2 Sensor bad. Then make sure you give us all of that. While there for FREE also they can bring their tester out and check your battery and alternator on the car. Have them do that and let me know what you find.
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Tuesday, December 17th, 2019 AT 7:23 PM (Merged)
Tiny
JORGERP
  • MEMBER
  • 3 POSTS
  • 2003 FORD FOCUS
  • 4 CYL
  • FWD
  • AUTOMATIC
  • 40,000 MILES
Hello, I changed my alternator and the battery at the same time and the battery light comes on and off, I got a mechanic to test the alternator and the alternator isn't good, then I we got a new one and it was tested good, before putting on car, the alternator was put on the car and battery light comes on again in sporadic times, I was told that this alternator turn. What can be the problem I ve spent alot of money and I just dont know what to do, can u pleas help?
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Tuesday, December 17th, 2019 AT 7:23 PM (Merged)
Tiny
BLUELIGHTNIN6
  • MECHANIC
  • 16,542 POSTS
Hello and thanks for the donation!

If your battery and alternator both test good then you need to inspect the charging system's cables. Make sure the battery cable ends are clean and tight properly at all connection points, including the starter.
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Tuesday, December 17th, 2019 AT 7:23 PM (Merged)
Tiny
JORGERP
  • MEMBER
  • 3 POSTS
When you say charging system cables what are they
battery cables or the cables that go to alternator
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Tuesday, December 17th, 2019 AT 7:23 PM (Merged)
Tiny
BLUELIGHTNIN6
  • MECHANIC
  • 16,542 POSTS
All of them. Entire charging system cables (cables from battery to alternator as well as to starter)
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Tuesday, December 17th, 2019 AT 7:23 PM (Merged)
Tiny
JORGERP
  • MEMBER
  • 3 POSTS
Thank you for your help!
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Tuesday, December 17th, 2019 AT 7:23 PM (Merged)
Tiny
ROBERT85
  • MEMBER
  • 11 POSTS
  • 2001 FORD FOCUS
  • 162,000 MILES
Car clicks real fast when key is turned to the on position, and won't do anything any suggestions died and shorted and died on the way to work, starter, alternator, and battery tested good any suggestions?
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Tuesday, December 17th, 2019 AT 7:23 PM (Merged)
Tiny
CARADIODOC
  • MECHANIC
  • 33,737 POSTS
The engine has to be running when you test the generator. How did you get the engine started if it "doesn't do anything"? Does that clicking occur when you try to start the engine or when you just turn the ignition switch to "on"? What shorted?

Start by measuring the battery voltage. It should be 12.6 volts if it's fully charged. If it's closer to 12.0 volts, it's okay but discharged. If it's around 11 volts, the battery has a shorted cell and must be replaced. Also check the battery cable connections to be sure they're clean and tight.
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Tuesday, December 17th, 2019 AT 7:23 PM (Merged)

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