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521 Alternator ground wire/battery wire

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The negative battery cable goes to the engine for ground, then where exactly does it ground on the alternator? I've read "the frame of the alternator" but I'm not sure what connector. It's a Hitachi alternator I believe, with the black plastic on the back, and doesn't have a "B" connector as I can tell, but rather "E" and "A" bolt/connectors and the "F" and "N" on the plug connector.

 

The cable seems short to the alternator, but maybe if I adjust it on the battery, I can barely get it to reach.

 

How could I have been running this whole time with this ground disconnected and no IGN light until now?

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Just make sure its not the bat + one haha. Find a nut/bolt thats not marked and you can ground it there, sometimes it has an E for earth, that one would work as well.

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Here are some pictures of the ground wire I put in my 521, from the engine lifting lug, down to the frame of the alternator.

Picture 1

Ground1.jpg

Picture 2

Ground4.jpg

 

It is the black wire, with red heat shrink near the terminal. the connection on the alternator is just a threaded hole, on the case, that is not insulated from anything.

 

Your alternator is currently grounding through the bolts that hold it on the engine. It needs the frame grounded to the battery cable. There is also a second black wire that goes to a voltage regulator mounting screw, under the same screw on the alternator frame. Even if you have an internal regulated alternator, this wire also must be in place.

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Here are some pictures of the ground wire I put in my 521, from the engine lifting lug, down to the frame of the alternator.

Picture 1

Ground1.jpg

Picture 2

Ground4.jpg

 

It is the black wire, with red heat shrink near the terminal. the connection on the alternator is just a threaded hole, on the case, that is not insulated from anything.

 

Your alternator is currently grounding through the bolts that hold it on the engine. It needs the frame grounded to the battery cable. There is also a second black wire that goes to a voltage regulator mounting screw, under the same screw on the alternator frame. Even if you have an internal regulated alternator, this wire also must be in place.

 

Thanks. The jumper cable off the negative battery cable didn't reach. Did my belt stretch or is it from another alternator? I took the spade off that cable and spliced it to another cable with a spade on it. and connected to the E on the alternator.

 

Voltage still dropping. Guess it's time to swap alternators. Might swap the voltage regulator first just in case.

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I just have a negative battery cable without the pigtail in it. I made a separate piece of wire this goes from the lifting eye to the alternator.

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Just make sure its not the bat + one haha. Find a nut/bolt thats not marked and you can ground it there, sometimes it has an E for earth, that one would work as well.

 

E is on the alternator, which makes sense as "Earth." There's another black cable off this one, which is the ground at the voltage regulator I assume, since the other terminal has the white wire which must go to the starter.

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here is a original set up. there are 2 grounds on the alt. the big black wire with the yellow stripe is the battery ground connected to the lift eye.

SANY1817.jpg

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I ended up ditching the ground. I had the hardest time getting two spade connectors on the alternator, almost as if it was made for one.

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Spade connectors? The Earth/Ground and Alt/Bat wires should not use spade connectors. They need a more permanent connection (Lug connectors bolted down securely). The F and N wires use T-connector spades.

 

Also, don't ditch (remove) the ground wire. Just add a new wire from alt E to the body, to supplement the factory wire from bat NEG cable to the body.

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You must have good grounds. You may think the alternator is bolted to everything, and that grounds it, and it will for a little while. But running electricity between two different types of metals, (aluminum alternator frame, steel bolts, and painted steel brackets) causes a electrolysis reaction that makes the metals corrode, or oxidize, and the connection will go bad.

This process is accelerated if any water gets in of on the parts.

 

All the electricity that comes out of the battery post on the alternator has to get back into it, because electricity goes in full circles, and if any part of the circle is broken, the electricity stops, or finds another way. If you have a higher output alternator, the alternator ground wire needs to be made bigger, just like the positive wire from the alternator has to be bigger.

 

Many Datsuns have had the wiring harness go up in smoke, because of electrical problems. Other Datsuns have had the throttle cable, and choke cable melt and become frozen, because the electricity tried to ground through the choke cable or throttle cable or linkage.

 

If you have an internal regulated alternator, and the ground connection is bad, the alternator will not have an accurate voltage to regulate to. This could cause the battery to not charge, or over charge, and boil all the water out. The water in the battery needs to stay there, not boiled out, and making body panels rust.

 

Make sure you have good grounds from the battery to the engine block, from the lifting lug to the alternator frame, from the alternator frame to the voltage regulator. if you have an internal regulated alternator, this old ground wire to the regulator must still be there, connecting the body sheet metal to the alternator. There is many times another black wire by the regulator position that grounds the headlights on some Datsuns. The grounded light switch on a 510 might be there, I do not know.

 

On Datsun pickups you must also make sure you have good grounds to the frame, the cab, and the bed of the truck, and well as the good connection from the engine to the battery, and the engine to the frame.

 

Many odd electrical problems are caused by bad grounds. Make sure all your electrical grounds are good.

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What's the other wire on the E then? I think mine must be wired differently. There was an OEM spade (not lug) that goes into the harness.

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This is the other wire on the "E" lug on the alternator.

 

"from the alternator frame to the voltage regulator. if you have an internal regulated alternator, this old ground wire to the regulator must still be there, connecting the body sheet metal to the alternator. "

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my 72 521 has a blk wire that looks like a C that is the ground I hook to E(earth) on the alter.sometimes they can slip off when screwing it down.

 

T connector

 

white/red wire to output threaded post.which is the +12volts

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