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Old 11-07-2010, 01:34 PM
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Bad alternator?

I probably already know the answer to this, but I just want someone with more knowledge to confirm it before I go and spend more $$$ (already have one truck in the shop getting a head gasket, ugh ) Anyway, I have an 85 chevy c10 that the battery has been dying on. Something was pulling 4.2 amps off it constantly. I traced the problem back to the alternator. It has three wires going to it. One is by itself and bolts to a terminal on the back. The other two are together on a connector that plugs in on the side. (I assume this is a "3 wire" alternator?) Unhooking the connector stops the 4.2 amp draw. Would this be the diode pack going bad?
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Old 11-08-2010, 10:40 AM
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The Alt is not the problem at all. But I do need more info,
Has the wireing been altered at all? I had a 82 camaro and the bubba I got it from had the alt wires running hot all the time and it would drain the battery in a matter of hours. I ended up re doing the wires to run just like this. and never had a problem after that.
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Old 11-10-2010, 10:30 PM
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if your 2 wire connector is backwards the draw would be high. your field would be energized all the time and the alternator casing would be very very warm. till the battery went dead.....
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Old 11-10-2010, 11:03 PM
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Quote:
Originally Posted by kd5icr
The Alt is not the problem at all. But I do need more info,
Has the wireing been altered at all? I had a 82 camaro and the bubba I got it from had the alt wires running hot all the time and it would drain the battery in a matter of hours. I ended up re doing the wires to run just like this. and never had a problem after that.
Thanks for the pic. That helps a lot.

Quote:
Originally Posted by DOCTOR DC
if your 2 wire connector is backwards the draw would be high. your field would be energized all the time and the alternator casing would be very very warm. till the battery went dead.....
If the red wire of the connector goes to the second post like the picture shows it may be on backwards. It's dark right now, but I'll take a look first thing tomorrow. Thanks to both of you.
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Old 11-25-2010, 02:20 AM
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i had a 10si alternator that was given to me a long while back.. and if that alt was left connected to unswitched 12v, it would wipe the battery out in about 24 hours. no idea why that one alternator did that. I moved the 'sense' wire to an ignition switched source and it stopped the problem.

one important question, is what kind of alternator are we working with? 85 I'm not sure of. my 86 astro had a CS130 on it.
are you using an older style with the two pin connector? or is it the newer type with the large 4 pin connector? (it may only have 1 or 2 wires, but it still has 4 positions)
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