79 750f dohc charging problems (what else can i do when its all new)

Okay so playing around with another r/r I have around 122 ohms at 12.62 volts and as I increased voltage ohm reading went down then went OL when I got close to 14 volts


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tccook said:
Okay so playing around with another r/r I have around 122 ohms at 12.62 volts and as I increased voltage ohm reading went down then went OL when I got close to 14 volts

Strange. It should be doing the opposite. We want resistance to increase as voltage increases. OL is OK as voltage gets past a certain point, but we should have low resistance at low voltage and resistance increasing as voltage increases.

I'll take a quick video of my setup when I get back to the shop later today.
 
2nd and 3rd R/Rs look OK to me.

Let's check over the wiring. The connections from the alternator and running directly to the R/R or do they pass through the harness at any point?
 
Sonreir said:
2nd and 3rd R/Rs look OK to me.

Let's check over the wiring. The connections from the alternator and running directly to the R/R or do they pass through the harness at any point?
No directly to r/r


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OK. Let's try a few other tests.

Ohm readings between each of the yellow wires and the negative terminal of the battery?

Also, with the alternator cover removed from the engine, ground out the white wire from the alternator and put 12V from the battery to the black wire. This should energize the field coil and it should be strong enough to hold up a 10mm wrench.
 
No. You can disconnect it. We're just checking to make sure that none of the yellow wires from the alternator are grounded. If you're able to get a reading between any of the yellow wires and ground, then there's a problem with the alternator.
 
Sonreir said:
No. You can disconnect it. We're just checking to make sure that none of the yellow wires from the alternator are grounded. If you're able to get a reading between any of the yellow wires and ground, then there's a problem with the alternator.

Okay those all said open loop



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On the next test I grounded white wire and applied 12 volts to the black and with the cover removed I couldn't get any thing to stick


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Sounds the field coil is non-functional or there might be an issue with the brushes. Double check that everything is assembled correctly and, if so, contact the manufacturer and see what they recommend.
 
Sonreir said:
Sounds the field coil is non-functional or there might be an issue with the brushes. Double check that everything is assembled correctly and, if so, contact the manufacturer and see what they recommend.

The wrench was supposed to stick to the outside of the alternator cover am I correct in thinking this?


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Sonreir said:
Sometimes. If you remove the cover it should definitely stick to the alternator, itself.

Okay sounds good I need to contact them then


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So I'm sitting here thinking out loud to myself if the alt cover is removed how is 12 volts supplied to the rotor? Or was I just supposed to loosen the cover ?


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lol... you're right. Sorry, I got my wires crossed. I'm too used to working with the twins. :p

You can jump a couple of wires from the battery to the exposed copper rings on the front of the coil and that should do the trick.
 
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