Nippondenso alternator is overcharging

A long time ago (2011) I started a serpentine belt swap on my Satellite. I have an LA 360 and I used the serpentine belt setup off of a 1991 Dakota (LA 318). I haven't messed with this project for quite some time, partially due to frustration and lack of motivation. Now I'm ready to get her back on the road. Here's a little background: I used the 1991 Dakota timing cover with the cast-in boss for the power steering pump. I got rid of the mechanical fuel pump and went electric, same thing for the fan. I used the Dakota reverse rotation water pump, P/S pump, compressor, alternator, and tensioner (with a swapped pulley). The car has a dual electric fan setup from a 2002 Camaro SS. The A/C & alternator brackets bolted on with no issues, and I eventually figured out the tensioner setup as well. The belt tracks straight and makes no noise. The major hang up was the alternator overcharging. I used the stock 90 amp, externally regulated Dakota alternator. I am no wiring genius, but I can generally read a diagram. I wired the alternator through the new-but-original-style voltage regulator, and bypassed the original 10 gauge ammeter charge wire and ran an actual battery cable (6 or 8 gauge, I can't remember) from the charge lug on the alternator straight to the battery. Well, it's putting 17.5 volts to the battery even at idle...regardless of whether the fans, lights, etc. are on or off. I swapped voltage regulators, no change. Got a Dakota voltage regulator, still no change. Tried swapping the green and blue field wires, no change. I don't know if it is bypassing the voltage regulator due to the added battery cable/charge wire or if it is simply overwhelming the voltage regulator. My local alternator rebuilder was no help whatsoever, they "don't build hot rods". I have not found any useful information on the net, no one that I've found makes an internally regulated Nippondenso alternator, and I haven't found an "other brand" internally regulated alternators that will fit this bracket or work with my current setup. Somebody please help!

i dont know if this will help.

a different one hope this helps.

and last but not least .

Thanks for the quick replies! I actually discovered what the issue is and it's a simple fix! I'm actually very embarrassed that it took me this long to figure it out. The regulator uses a reference voltage. The reference voltage was all out of whack thanks to a bad ground at the alternator case. After fiddling around with it this morning, I eventually ran a jumper wire from the ground stud on the alternator case to the regulator body/firewall and the voltage dropped to 14.19 and stayed very steady regardless of RPM. A bad ground. Fixed! Thank you again, vance.dykes!

Matthewf229 said:

Thanks for the quick replies! I actually discovered what the issue is and it's a simple fix! I'm actually very embarrassed that it took me this long to figure it out. The regulator uses a reference voltage. The reference voltage was all out of whack thanks to a bad ground at the alternator case. After fiddling around with it this morning, I eventually ran a jumper wire from the ground stud on the alternator case to the regulator body/firewall and the voltage dropped to 14.19 and stayed very steady regardless of RPM. A bad ground. Fixed! Thank you again, vance.dykes!

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your welcome glad to hear you fixed it.

Weak reference voltage is the cause of many over charging problems. Most of us have been there.

Glad you found it and by the way, Welcome aboard!