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Battery Light staying on???

WildBillMI
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Battery Light staying on???

What are the most likely causes of the battery light staying on in the instrument cluster?

I just replaced the battery last week w/ a brand new one (not because of this issue). The light came on after I got it back from the exhaust shop. I did the homemade mil-eliminator for the O2 sensor (new one of those as well) and that solved the check engine light from going cat-less....but now I have the battery light staying on.

Is it possible it's an issue with the alternator? The ammeter shows a normal voltage...right on the M in NORMAL.

Any ideas or things for me to check?

-WildBill
1995 F-150 5.0 Flareside Ext Cab

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thefordmaniac
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Post by thefordmaniac »

have the alternator tested. it may have the voltage but not the amperage.

-mike

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mjsecrist
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Post by mjsecrist »

Not sure about the '95 model, but on my '01 the battery light on means the charging system is bad. Mine actually had a good alternator but the alternator field fuse was blown.

WildBillMI
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Post by WildBillMI »

Well I checked the manual and PDB....

According to the manual... Fuse location 17 in the PDB (50 amp maxi) is the Alternator charge lamp and that one is still ok...

Is there any other fuse or relay that could be involved?

I'm going to see about getting the alternator tested tomorrow.

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Raven129
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Post by Raven129 »

Sounds like the alternator isn't charging. I'd definitely get it tested. Hook up a voltmeter to the battery, it should read about 12 volts with the truck off and about 14 volts with the engine running. If you don't have higher voltage with the engine running, the alternator isn't charging.

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Post by WildBillMI »

Ok...will do...

So if I have to replace it, I'm guessing a 130amp is a good idea? I have a bunch of stereo equip going in this spring (when I can work on it w/o a coat or heater on, lol...)

Any brands / stores to stay away from? I was thinking of trying to find one at a local parts store so I can return it w/ their warranty...vs ordering from Summit for ex.

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kevinskaggs46
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Post by kevinskaggs46 »

Heres a link for a heavy duty aftermarket alternator. Kind of pricey but you get what you pay for right?
http://www.autopartswarehouse.com/searc ... rd%20F-150

1995 Ford F150 5.0L V8 5Spd Man.
K&N Air Intake, Dynomax Headers, Magnaflow single 3-inch exhaust MSD ignition coil, MSD Cap and Rotor, WARN premium manual hubs, Dana 44 front, 32 in. Dueller A/T's Alpine Deck and Speakers w/ Ipod connect

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Raven129
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Post by Raven129 »

When I replaced mine, I went with a 130 amp. I got mine at Car Quest and for some reason it was actually cheaper than the stock 95 amp.

WildBillMI
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Post by WildBillMI »

Ok, I can't find my voltmeter this morning, lol...still looking but what I tried so far was yanking the negative battery cable after the truck was running and it didn't skip a beat...so shouldn't that be a sign that the alternator is working?

Also what I don't understand (and it could just be me) is why the needle never drops on the volt gauge in the dash? Shouldn't that dip down if the alternator isn't keeping the battery charged up?

I'm going to run over to a parts store on lunch and have them test the alternator...if it checks out good what are the next things to look for?

-WildBill
1995 F-150 5.0 Flareside Ext Cab

WildBillMI
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Post by WildBillMI »

I took the truck over to an auto parts shop and had the alternator tested...wouldn't you know on the way over the battery light finally goes out, lol. Anyway it tested good, 14.5 volts and I forget how many amps but it checked out...so is it possible it's a cracked diode or something starting to go in it that is causing a faulty light trigger?

-WildBill
1995 F-150 5.0 Flareside Ext Cab

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subford
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Post by subford »

More than likely wiring and wiring connections.
You need to clean them all between the Alternator and the battery.

What the light means:
With the ignition key in the RUN position, voltage is applied through the charge lamp I circuit to the voltage regulator. This turns the regulator on allowing current to flow from the battery sense A circuit to the alternator field coil. When the engine is started, the alternator begins to generate alternating (AC) current which is converted to direct (DC) current by the rectifier assembly internal to the alternator. This current is then supplied to the vehicle's electrical system through the output located on the rear of the alternator.

Once the alternator begins generating current, a voltage signal is taken from the alternator stator and fed back to the regulator S circuit, turning off the charge indicator (battery symbol).

With the system functioning normally, the alternator output current is determined by the voltage of the A circuit (battery sense voltage). The A circuit voltage is compared to a voltage internal to the regulator, and the regulator controls the alternator field current. The reference voltage will vary with temperature and is typically higher in the winter than in the summer, allowing for better battery recharge in the winter and reducing the chance of overcharging the battery in the summer.
Here os a diagram of the Ford Alternator:
http://i54.photobucket.com/albums/g91/s ... rnator.jpg

/

Bill
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1995 F150 5.0 4R70W
1988 E150 5.0 AOD
1983 F150 5.8 AOD
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1977 F250 351M 4x4 4 Speed
Any comments I make is for a stock wired truck with no modifications unless noted.

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Post by Goofyexponent »

i had the same problem with my 1996. the little red battery light stayed on, but the charge was reading 14.4 volts. I bought a new alternator and the same thing was happening. Turned out to the GREEN wire on the plug to the alternator was broken. There are 3 wires (Black, White and Green). The GREEN wire, which is the alternator's way of telling the computer and dash that it is chargine fine, was chaffed and it corroded so bad it was not sending the information to the computer and gage. It was actually charging up fine, but the computer couldnt read this. All I did to fix this, was find the broken GREEN wire, spliced in a new piece and voila! the light was out and i had a brand new alternator i did not need.

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subford
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Post by subford »

Goofyexponent wrote:The GREEN wire, which is the alternator's way of telling the computer and dash that it is chargine fine

The green wire has nothing to do with the computer and the charging system is not monitored by the computer.
The green wire provides the exciter voltage to start the alternator (A/C Generator) generating power to maintain the battery charge and power the accessories.
If then the voltage on the green wire is less or more the voltage (state of charge) of the battery the bulb will light. The more the difference in the voltage the brighter the dash lamp. There is also a lamp burnout resister around the bulb to provide power to the alternator if the bulb is burned out so the alternator will charge. This resister also keeps the bulb from lighting if the two voltages are close to each other.

Bill
[email protected]
1995 F150 5.0 4R70W
1988 E150 5.0 AOD
1983 F150 5.8 AOD
1982 E350 7.5 C6 Class "C" M.H.
1977 F250 351M 4x4 4 Speed
Any comments I make is for a stock wired truck with no modifications unless noted.

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thefordmaniac
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Post by thefordmaniac »

subford wrote:With the ignition key in the RUN position, voltage is applied through the charge lamp I circuit to the voltage regulator. This turns the regulator on allowing current to flow from the battery sense A circuit to the alternator field coil. When the engine is started, the alternator begins to generate alternating (AC) current which is converted to direct (DC) current by the rectifier assembly internal to the alternator. This current is then supplied to the vehicle's electrical system through the output located on the rear of the alternator.

Once the alternator begins generating current, a voltage signal is taken from the alternator stator and fed back to the regulator S circuit, turning off the charge indicator (battery symbol).

With the system functioning normally, the alternator output current is determined by the voltage of the A circuit (battery sense voltage). The A circuit voltage is compared to a voltage internal to the regulator, and the regulator controls the alternator field current. The reference voltage will vary with temperature and is typically higher in the winter than in the summer, allowing for better battery recharge in the winter and reducing the chance of overcharging the battery in the summer.

out of a Ford manual I presume? hehe

-mike

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Re: Battery Light staying on???

Post by steeler_guy »

same thing happen to me. my batt light was going on and off. figured the alt was starting to fail. bought one from napa and all is good for now. im a tech at toyota so i got a discount on top of a cheap reman alt. at least it has a lifetime warranty. the light is gone. yeppee :cheer:

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kevinskaggs46
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Re: Battery Light staying on???

Post by kevinskaggs46 »

Definitely check your main battery cables. Mine we're corroded way down inside the insulation and putting up enough resistance to keep me from getting a good charge.

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Re: Battery Light staying on???

Post by packyd »

I had the same problem but I had a simple fix. There is a 20amp fuse in the engine bay fuse block marked #11 that is for the alternator field windings. If this fuse blowes you are going to draw power directly from your battery because your alternator output is 0 volts. Of course you also have to find out what made the fuse blow. I looked at the wiring diagram from "subford's" link but this diagram doesn't show the 20amp fuse, only the fusable link. I hope this helps.

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Re: Battery Light staying on???

Post by kraut68 »

2003 F150 batt light came on, replaced alt and battery. Light is intermittant now, it flickers, goes out, comes on. Any suggestions where to check? I'm thinking a bad wire, ground or connection.......

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Re: Battery Light staying on???

Post by lupin398 »

kraut68 wrote:2003 F150 batt light came on

You'd be better off posting in the newer truck section since the hardware and wiring diagrams are completely different.

Also if you're going to replace it, there's a way to upgrade to a 3G alternator from a 2G alternator(what our trucks have) They are rated as higher so they can probably run more stuff and I believe they're also much less likely to burst into flame when aggravated.

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Re: Battery Light staying on???

Post by autofame »

[quote="WildBillMI"]What are the most likely causes of the battery light staying on in the instrument cluster?

I just replaced the battery last week w/ a brand new one (not because of this issue). The light came on after I got it back from the exhaust shop. I did the homemade mil-eliminator for the O2 sensor (new one of those as well) and that solved the check engine light from going cat-less....but now I have the battery light staying on.

Is it possible it's an issue with the alternator? The ammeter shows a normal voltage...right on the M in NORMAL.

Any ideas or things for me to check?[/quote

yeah

these alternators are controled by pcm(powertrain control module) unplug the alternato plus with 3 wires leave the power wire on then check with test light one should b ground(black) blu(ign)shouldnt show power when start position
pink or tan(is a signal wire to instrument cluster for battery light) put ur test light on ground and connect it with pink ur battery light should turn on in instrument cluster. if everything is good ur regulator is not good might cost you lot if u take it to dealer if yuh wanna bypass here cut the tan wire from the plug and link it with ur test light via ground. alternaot should work on 14volts