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Voltage spikes under hard load?

ctnsupra1

NAXJA Forum User
Location
MD
Okay so I'm electrical gremlins giving me issues, I had another thread going on here http://naxja.org/forum/showthread.php?p=245566816#post24556681. I found a loose wire to the alternator that I tightened and figured all was well.

Tonight I tested things out and WHOA! Under load with my lights on the headlights became noticeably brighter and dash voltage meter begged the red at 19+ volts! Any ideas on what would cause this? The alternator is a 136a unit that I bought new less than a year ago. The CEL that popped showed a 12 and 41 which are battery recently disconnected and alternator field control circuit opened or shorted.
 
Check the pattery terminal connections and the condition of the battery
cables/grounds. I had a similar event one day, it was a loose (+) cable
at the battery. I think the regulator increases output voltage if the
battery voltage drops low. That would occur if your battery cable were faulty or loosely connected.
 
I went through the cables (there's a lot, they're connected to an Optima blue top that's only 8 months old) and tightened everything back up just to make sure. I'll check the engine to chassis ground at the back of the motor but I've redone all the wiring to 0 and 0/1 so grounds should be okay.
 
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