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Discussion Starter · #1 ·
I can't seem to get rid of this gremlin, but I'm tired of blowing up batteries. I got stranded last Friday after work, and got a face-full of boiling hot battery acid when I opened my trunk.
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B, S, and G wires are both fine, but I noticed that G is two volts lower than battery (measuring at the alternator end). I can't find much info on how the wiring for the voltage regulator works (or terminal G specifically) in the SM, but I read somewhere that the ECM has some influence on the regulator, so G is next on the chopping block.

Before I resume hacking things up, does anyone know if that's normal behaviour for G? Am I barking up the wrong tree?
 

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I'm not 100% on our cars but typically one of those wires is the exciter that just tells the alternator to put out charging voltage. I think you got a bum replacement alternator since that charging output should be 14-14.5v not 18v.
 

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Discussion Starter · #4 ·
Did you replace the alternator? Sounds like the regulator is shot.
I'm not 100% on our cars but typically one of those wires is the exciter that just tells the alternator to put out charging voltage. I think you got a bum replacement alternator since that charging output should be 14-14.5v not 18v.
Old and new alternator were both for doing it. It started after an engine swap. It's possible it's bad, but I'm looking for anything else first.
 

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Post engine swap you say? Check the voltage for the battery at the alternator with the car off. If it's low, the car may be seeing more demand for charging than you need. Could be resistance in the positive cable from the battery (check with a multimeter) or a grounding problem.
 

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Discussion Starter · #6 ·
Post engine swap you say? Check the voltage for the battery at the alternator with the car off. If it's low, the car may be seeing more demand for charging than you need. Could be resistance in the positive cable from the battery (check with a multimeter) or a grounding problem.
Voltage is ultra high (last I checked on the latest was 15.8). I haven't checked for voltage drop or resistance from the battery, but I'm using a new length 02 Gauge wire, so I don't imagine there's much lol. I'll double check.
 
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