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Soccercop
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Jul 7, 2010, 11:49 AM
Post #1 of 13
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Ford Focus battery light
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Hi All,
Looking for your expert advice.
2006 Ford Focus ST, 2.3L 4, Manual trans with 93K on the clock
Battery light comes on after using the AC for a few minutes. Light resets once RPMs drop below 1000. No belt noise, no other electrical issues noted, like noise in radio (even AM) or dimming lights or turn signal flash speed, etc. Tried driving without AC, but it's over 100 degrees right now in NJ-light doesn't seem to come on at all as long as I don't use AC.
Also noted that from time to time (no obvious pattern indicated) when I approach a stop and depress the clutch, the engine almost stalls, but catches just before it dies, then idles properly and smoothly at about 750.
Unemployed means I can't afford to let Ford experiment by replacing parts at my expense till they figure it out. Wife said perhaps run it till something dies, then you'll know the defective part.
Thanks for your insight!
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Hammer Time
Ultimate Carjunky
/ Moderator
Jul 7, 2010, 12:19 PM
Post #2 of 13
(7863 views)
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Re: Ford Focus battery light
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You can't afford to let the professionals experiment but you want to experiment yourself?
What you need to do is test the charging voltage while that light is on to determine what is going on with the charging system.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Soccercop
User
Jul 8, 2010, 10:59 AM
Post #3 of 13
(7852 views)
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Re: Ford Focus battery light
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Attached a multimeter to the cigarette light socket:
car off-12.8V
running @ idle 13.3
running @2000 RPMs 14.2
just the slightest bump (downward) when the light turns on-no appreciative changes with light on or off.
today noticed that the car idles at/near 250 RPMs after the light turns on. The "Batt" light resets after a few moments below 1000, and idle returns to about 750. Strangest thing-it seems that the use of AC contributes tremendously to this symptom (reduces the time of driving till the light comes on), and that there seems to be no other typical symptoms of electrical issue (like dimming lights, etc).
I've looked around on lots of forums-seems like Ford can't fix this-people claiming to have this persist after replacing battery, alternator, engine control module.
And I'm not experimenting-simply picking the brains of others that might be able to point me in the right direction. Trying to proceed intelligently, since it is apparent that simply "throwing it on the machine" hasn't seemed to help others with similar symptoms.
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Hammer Time
Ultimate Carjunky
/ Moderator
Jul 8, 2010, 11:19 AM
Post #4 of 13
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Re: Ford Focus battery light
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If your maintaining over 14v when the light comes on, then the light is not working properly. The light is controlled by the voltage regulator which is an integral part of the alternator. It may or may not be sold separately.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Soccercop
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Jul 8, 2010, 11:36 AM
Post #5 of 13
(7845 views)
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Re: Ford Focus battery light
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Thanks HT-so you're thinking the defect is in the indicator light (the system telling it to turn on), not the operation of the charging system?
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Hammer Time
Ultimate Carjunky
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Jul 8, 2010, 11:47 AM
Post #6 of 13
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Re: Ford Focus battery light
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Yes, if your sure the voltage was in the 14v range during the period the light was on, then the light is not working correctly which is controlled by the voltage regulator.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
(This post was edited by Hammer Time on Jul 8, 2010, 11:48 AM)
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Soccercop
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Jul 8, 2010, 11:52 AM
Post #7 of 13
(7837 views)
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Re: Ford Focus battery light
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Thanks HT!
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Soccercop
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Jul 12, 2010, 10:38 AM
Post #8 of 13
(7825 views)
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Re: Ford Focus battery light
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More (interesting, I hope) info on this trouble.
Seems to be temperature-related, as the past few days have been a bunch cooler, and no further battery indicator (even with AC on).
I'm wondering how this might contribute to the problem, hmm.
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Hammer Time
Ultimate Carjunky
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Jul 12, 2010, 2:50 PM
Post #9 of 13
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Re: Ford Focus battery light
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Nearly all electronic component failure are heat or corrosion related.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Soccercop
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Jul 21, 2010, 12:06 PM
Post #10 of 13
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Re: Ford Focus battery light
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The continuing saga
Along with the return of the 90 degree weather-my batt light is back on.
Thought maybe a poor or high-resistance connection somewhere, I used a plastic mallet to tap on each of the high-current connections I could get to. No change.
Had the charging system checked-their diagnostic system concurred with our earlier findings (pretty solid 14VDC with or without the light on)-the charging system seems to be functioning properly, so I replaced the battery. FYI-I noted on the old one coming out that two of the middle cells were low on electrolyte. As it was five years old, I was optimistic that the battery was the cause of this issue.
Replaced it-I was wrong. Battery light is back on. Time, money and brain cells wasted.
Might the car's electronics need to "learn" that it has a new battery to return to complete normal? I figure I'll drive it for a couple days with the new battery. If the light doesn't go out and stay out, I'll put the old one back in and run the car until whatever is failing completely toasts, saving the new battery for the repairs in the aftermath.
Appreciate hearing from you if anyone has any other suggestions-or am I just another one of the Focus owners stuck with a battery light on with no answers?
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Hammer Time
Ultimate Carjunky
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Jul 21, 2010, 12:12 PM
Post #11 of 13
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Re: Ford Focus battery light
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I guess you weren't listening the first time. Contrary to popular belief, the battery light has nothing to do with the condition of the battery. As I told you earlier, the light is controlled by the voltage regulator which is integral to the alternator. The only other things than can do it are the wiring to the dash or a problem in the dash circuit itself.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Sidom
Veteran
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Jul 21, 2010, 10:29 PM
Post #12 of 13
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Re: Ford Focus battery light
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Just one quick suggestion to see if this is a load problem related to the charging system or if the problem is in the area of something just turning the light one when it shouldn't be on.....
Using the a/c puts a good load on the system. If the car has a heated rear window. When the problem is happening turn the a/c off & the rear defroster on (this is the highest single load devise there is). If the battery light turn turns on with the rear defroster on then it's load related to the charging system. If not then the problem is somewhere else........
(This post was edited by Sidom on Jul 21, 2010, 10:30 PM)
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Soccercop
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Jul 26, 2010, 11:12 AM
Post #13 of 13
(7757 views)
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Re: Ford Focus battery light
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On more than just on forum, I got the distinct impression that the Ford Focus had some sort of mystery surrounding my Battery light symptom. At least four instances were cited where the post indicated both battery and alternator replacement did not resolve their battery light issues. $120 for a battery, $600-800 I read were typical costs for alternator replacements, all to no avail. From this, I concluded that there was some other potential cause for my problem.
I ended up buying a new battery, based on the results of a test by a local shop. Not the answer. I decided to put the old battery back in and drive the car till something fell out of it. Then, I would be certain of the defective component.
My alternator toasted on Saturday night. As I might expect, once the alt finally gave up the ghost, the appropriate computer shut off all non-essential electricals, providing all available power to the engine (and, I supposed fuel pump) until the battery was too exhausted. It got me as far as I needed to go.
In NJ, one of the few service agents open on Sunday was Pep Boys. They secured an alternator from NAPA and installed it in a couple hours for $472. No mystery, no rocket science.
Seems like my ST and I are back in Focus.
Now, onto the reverse light switch.
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