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New alternator, car doesn't shut off

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1977 Datsun 620 I know this has been talked about before and the typical answer was "switch back to stick alt". Well my stock one fried! I got an AC Delco one that fit in perfect and had all the same connections. So of course the car won't shut off with the key but if I disconnect that T connector it shuts off but of course stops charging. Is there any sort of fix for this, as I know it's internally regulated?

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77 is external or internal reg alternator????

You say you have a internal volt reg alt. so is the truck a external or internal type wired?

If external type and you installed a internal type  Alt then you need to make the jumpers as mentioned above but you would have a battery drain issue with the choke relayalso


more info is needed as 77/78 is a crossover for the intenernal volt reg type alternators

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There is no 'stick alternator' There are externally regulated (up and including '77) and there are alternators with the regulator built in or internally regulated (all Nissan/Datsun from '78 and up)
You have an internally regulated alternator on an externally regulated truck. You need to 'convert' your wiring harness to use this. Take the external regulator off and cut it away from the plug keeping the wires as long as possible. Slip some heat shrink tubing over the Yellow and the Yellow/Whiter wires for later. Now join and SOLDER the Yellow and the White wires together. Then join and SOLDER the White/Yellow stripe and the White/Red stripe wires together. Slid the heat shrink tubing over the soldered connections and heat to shrink them to make a water proof covering. When done it should look ike this after removing any other wires in the plug....

I can't stress soldering the connection enough, so it gives you no problems later. Heat shrink tubing is the better way but you can tape them, but I do not recommend this.



Now plug this back onto the harness where the external regulator was.


Not done yet.


Unfortunately this wires the auto choke on at all times, even when the key is off, so find the auto choke heater relay and disconnect it from the harness at least, or remove it completely. If you leave it connected, it will discharge your battery over a weekend.


To make your auto choke operational again you need a new power supply that is switched off with the ignition. Simplest thing is to find the Blue auto choke wire on the carb and the Red idle cut solenoid right beside it. Unplug the Blue auto choke wire from the engine harness and join it to the Red idle cut wire and you are done. The idle cut turns on and off with the key. My 620 and both my 710 were done this way.

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did you order the wrong alternator?

How about put the correct one in and you dont have to do any of these mods.


most use the connector from the external volt reg and cut it off and put the jumpers there and pplug into the stock harness.  But I would just get a 77 alt and dont worry about the battery drain and connector mod. But we are just guessing what is really real with your truck

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did you order the wrong alternator?

How about put the correct one in and you dont have to do any of these mods.



This is the most practical but if the new one has higher output or already in or can't take back, conversion is another way to go.


The plug shown is just an example. Different years and models had different makers.suppliers. Connect the wires as shown. Those regulators are mechanical and are not cheap when they blow either.

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