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Swapping to IR Alternator


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I have a 77 620 I am swapping over to an 80's subaru alt. Looking at the wiring the PO spliced a wire from the ballast resistor into the white/blue wire coming off the regulator, which is eliminated when removing the external regulator. I see that the white/blue wire runs to the fuse panel from the 76 wiring diagram. What was the purpose of the wire originally, and does anyone have a link to a working good quality 77 wiring diagram.

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white/blk stripe SHORT with white / red stripe

then yellow SHORT with white.


this is a datsun 510 but should be the same on the trucks


i dont know white blue stripe but alot of people hook to the Ballast as its a switchable 12volt. you sure its not going to the carb choke or something. Sounds kinda hoky to jump a wire from drivers side to the pass side to get 12volts

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There should be two wires to the old carb. A Red for the idle cut... only on with the ignition. A Blue wire to the choke heater (from the choke relay)... only on when running. The Red wire is a good source for 12 volts when starting and running and could be fed to the points and the ballast resister if needed.


Hainz is totally correct about the choke relay. If not disconnected the small coil inside is energized constantly and will slowly drain your battery over a weekend..

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I removed the wire from the ballast and was getting ~11v still. Thanks for the heads up on the relay, its now unplugged. Gonna hijack my own thread and go ahead and ask what this is.


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that orangish wire is the one i was talking about earlier that runs to the ballast. I was thinking about adding a/c back in, would have to figure out a way to bump the idle on a weber when ac is running

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Spliced to the white/blue wire. I can't find a good 77 wiring diagram, but looking at a 76 the wire starts at the regulator and runs to the fuse panel. So far I can' tell that it does anything after unhooking it. Confused as to why this was done.

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make sure our charging and its regulating correctly.


My first thought maybe the alternator wasnt getting the 12volts for the alternator winding will have power so your alt camn make output



but im not familiar with the 620 and the wht blu wire.



my 521 truck I had no output on my alt. I swapped another alt and a volt reg only to find out I had no 12volt at the T connector to get 12volts on the windings.


I reseat the instrumen panel harness in back and I guess it passed 12volts thru there via the IGN lamp light. then it was good.

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Swapped the alternator out for a 60 amp IR alternator, tested while running was about ~14v, so it seems to be running fine w/o it hooked up. I didn't do any testing before I pulled the old one so maybe it served some purpose like you mentioned for the original set up.

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