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86-95 Trucks & 4Runners 2nd/3rd gen pickups, and 1st/2nd gen 4Runners with IFS

Battery/Alt problem

Old Apr 4, 2013 | 10:19 PM
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Battery/Alt problem

So heres what ive got so far, i went out mudding the other day with some friends and got everything really dirty, i washed my truck and let it sit overnight. The next day i went to start it and it wouldnt turn over, the battery was dead. I got a buddy to jump me and it started fine and seemed to be charging when i drove it around, i noticed that using my turn signals was dropping the voltage in my battery. So i hooked up a volt meter to it and it was reading as if the polarity was reversed? Is there anyway to test my alternator/ battery?
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Old Apr 4, 2013 | 10:26 PM
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Take your truck to any auto parts store, they can test the charging system and battery.

Before you do, make sure all your cables and connections are good. Remove both terminals, clean then really well, and reassemble. I can't tell you the number of "charging problems" I have remedied on customers cars by simply cleaning the terminals.
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Old Apr 5, 2013 | 02:25 PM
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Originally Posted by DeathCougar
Take your truck to any auto parts store, they can test the charging system and battery.

Before you do, make sure all your cables and connections are good. Remove both terminals, clean then really well, and reassemble. I can't tell you the number of "charging problems" I have remedied on customers cars by simply cleaning the terminals.
Thanks for the info DC. The connections all seemed to all be fine. I dropped in a new battery and took it for a drive this morning and it appears to be overcharging. I also get the charge/ brake light above 2000rpms. I'm assuming this is a problem with the Alternator. Could a bad alt cause these symptoms?
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Old Apr 5, 2013 | 02:36 PM
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The alternator has a built in voltage regulator. If it's over-charging, you probably need a new alternator
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Old Apr 5, 2013 | 03:13 PM
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Originally Posted by smithyboy69
... it appears to be overcharging.
Put your voltmeter right on the battery. If it's over 15.1v while running, you're overcharging. http://personal.utulsa.edu/~nathan-b.../2onvehicl.pdf

Too high voltage on the battery is an excellent way to fry a new battery in short order.

If the voltage is too high, you need a new voltage regulator. Unfortunately (fortunately?), entire reman alternators don't cost any more than the regulator. So take the alternator to a store that offers free testing, and be prepared to buy a replacement.
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Old Apr 6, 2013 | 09:37 AM
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So i guess i fixed my issue... i traced my harness all the way back to the battery and found a random blue wire poking out, i connected this wire to ground and everything seems to be fixed.. i have no idea what this wire is or does but its clearly not supposed to be there. Could a bad ground really cause a battery to drain and then a new battery to overcharge?
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Old Apr 10, 2013 | 11:02 PM
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The problem came back today, woke up to go to work and the battery was dead, luckily i had a spare. The charge and brake light started flashing on/off as i went over bumps in the road, so i assumed once again something wasnt grounding properly, i put new terminals on and rewired my grounds and it went away for an hour but is now back, and my battery now doesnt charge while driving. So i assume my alt just died, i have a visually identical honda alt in my garage but it has a different pulley, can i simply swap the pulleys and then throw it in?
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Old Apr 11, 2013 | 05:23 AM
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Originally Posted by DeathCougar
Take your truck to any auto parts store, they can test the charging system
What were the results of the test?
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Old Apr 11, 2013 | 06:50 PM
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Originally Posted by j2the-e
What were the results of the test?
I live in a small town in bc, the only auto parts store is napa and they told me they couldn't do anything. I replaced the alt this mornIng and everything seems to be back to normal.
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