Faulty Charging System in 521

[AcesHigh]

Hi Everyone! I just bought a 1970 521 2 weeks ago and after driving for a week, the ignition light came on while engine was running. The battery was not holding a charge so I replaced that. I had the alternator bench tested and it failed, I bought a new one and that one passed the bench test. The light is still on. Before I explain my concerns, here are some pictures of the engine compartment:

 

 

 

 

 

 

 

 

These tests I ran are from GGZILA:

 

1. With engine OFF, key OFF measure voltage at ALTERNATOR A terminal (or BAT terminal) and alternator case. If you get the same voltage as at the battery terminals it's good. If you get lower voltage, you have a wiring problem.

GOOD!

 

2. Unplug the T-connector and start the engine. Put your Voltmeter on the battery terminals. Jump a wire from alternator BAT to the F terminal of the alternator. If the voltage jumps up, the alternator is working. CAUTION: Don't let the voltage go over 17volts. If the voltage doesn't change, you got a bad alternator (new ones can be bad too).

GOOD!

 

3. If the alternator worked when jumpered, now test the wiring from the regulator. Unplug the voltage regulator and start the engine. In the harness regulator connector jump the White-with-black-stripe wire to Battery +. If the voltage jumps up, thats's good. if it doesn't, the wiring harness is bad somewhere.

BAD! When I jump white with black stripe to the positive battery terminal, the motor slows down and there is no voltage change.

 

4. Check the harness feed wires. The White wire should read 12V when key is OFF. If not, there is a wiring problem somewhere.

GOOD!

 

5. Between the White wire and the Black wire you should have 12V. If not you have a ground problem.

GOOD!

 

6. With KEY ON engine OFF, check that White/blue stripe wire has 12V.

BAD!

 

Please help me, I will love you!

 

Here is a link to the wiring diagram

http://higherintelle..._Diagram[1].bmp

[wayno]

Hi Everyone! I just bought a 1970 521 2 weeks ago and after driving for a week, the ignition light came on while engine was running. The battery was not holding a charge so I replaced that. I had the alternator bench tested and it failed, I bought a new one and that one passed the bench test. The light is still on. Before I explain my concerns, here are some pictures of the engine compartment:

 

 

 

 

 

 

 

These tests I ran are from Wayno:

1. With engine OFF, key OFF measure voltage at ALTERNATOR A terminal (or BAT terminal) and alternator case. If you get the same voltage as at the battery terminals it's good. If you get lower voltage, you have a wiring problem.

 

I have no voltage showing. After studying the wiring diagrams, I noticed the alternator A terminal (BAT) should go to the voltage regulator and the positive battery terminal. In my truck, this wire connects to the (negative side??) starter. From the same terminal another smaller wire goes to the voltage regulator. I believe these wires are on the wrong terminal.. because when I connected them to the terminal with the positive battery wire, 12.5v were going to the alternator.

 

2. Unplug the T-connector and start the engine. Put your Voltmeter on the battery terminals. Jump a wire from alternator BAT to the F terminal of the alternator. If the voltage jumps up, the alternator is working. CAUTION: Don't let the voltage go over 17volts. If the voltage doesn't change, you got a bad alternator (new ones can be bad too).

 

The voltage does not change. This may be because the alternator BAT wire goes to the wrong side of the starter? Does anyone have experience with this and willing to help me?

 

Here is a link to the wiring diagram

http://higherintelle..._Diagram[1].bmp

 

 

Are you sure you got the info from me, I don't know a lot about this subject.

Externally/internally regulated charging systems are more or less a mystery to me, my ignition light came on in my 521 a few years ago, but it was still charging, Ryan at baxters was confused about my light being on also, as he was the one that tested it.

It finally quit charging without warning because the light had been on for at least a year, I put 3 alts. in it, and two regulators, and the light wouldn't go out, so I changed over to an internally regulated alt. and used jumper wires at the regulator plug, and it has worked fine since.

I may have repeated what someone like ggzilla or datzenmike said about an alternator test, but other than that, I wouldn't listen to me. :lol:

[AcesHigh]

Are you sure you got the info from me, I don't know a lot about this subject.

Externally/internally regulated charging systems are more or less a mystery to me, my ignition light came on in my 521 a few years ago, but it was still charging, Ryan at baxters was confused about my light being on also, as he was the one that tested it.

It finally quit charging without warning because the light had been on for at least a year, I put 3 alts. in it, and two regulators, and the light wouldn't go out, so I changed over to an internally regulated alt. and used jumper wires at the regulator plug, and it has worked fine since.

I may have repeated what someone like ggzilla or datzenmike said about an alternator test, but other than that, I wouldn't listen to me. :lol:

I found out it was from GGZILLA. I wouldnt have a problem switching to internally regulated, except that the alternator isn't charging the battery. I re-tested the system and put the answers up in the original post

[dat521gatherer]

Yeah you have a mystery relay box on the firewall with non original wires. If you want to try to have one of these smarter people try to help you trouble shoot it thats fine. But what I do when I get a new to me vehicle is remove all the non stock added on after market stuff to get back to bare bones as close as possible. It becomes really hard to trouble shoot and fix previous owners hack jobs.

 

I for one would take that fuse box down to the machine shop and have it sand blasted and then find a cover for it. Probably cost you $10 plus a top maybe another $10 if you post a ad in the wanted section. Check for cracks in the base of the fuse box if you remove it.

 

As far as the mystery box you should have 4 relays on the inner right fender. horn, head lights, e1 or e2, voltage regulator. The link you posted is for a L521 which I dont see the e1 or e2 relays which I think is for the dual points distributor. Here is a wiring diagram for the pl521. I know I'm not being much help here. I'm not great with wiring. When I got my red 71 521 the voltage regulator wires had been cut along with everything else so I just replaced the whole engine bay harness with a good used uncut one for $40.

 

Click on diagram to enlarge.

[ggzilla]

#6 results indicates the Regulator fuse is blown or has a bad connection. Check the fuse box. If the fuse looks good, pull it and sand the ends (sand the clips in the fuse box too) and put back in.

 

The steps above are for LS type alternator swap, so #3 doesn't apply. Ignore the results of #3.

[AcesHigh]

Thank you so much for the pl521 diagram! I cleaned the fuse box by soaking it in vinegar for a few hours. I thought about the ground on the alternator and tried moving it to a different location on the alternator and VOLA! no more ignition light!! damn, spending two days looking for bad connections and fuses can be a pain. Thanks guys for responding, even saying what you've experienced has helped out and I admire every datsun owner!

[wayno]

I am confused by this photo of the starter solenoid, why do wires go to 3 differant posts, I have wires going to only two posts, starter exciter wire, and the main post that has the battery cable, alternator cable, and the other wire that I don't recall where it goes.

Is the starter motor on a relay?

This is differant than any datsun I have owned.

[ggzilla]

Yes, Datsun starters have a relay. It's part of the "Starter Solenoid" which in addition to relaying the current also pulls the gear into position.

* Big Terminal 1: Battery POS cable (and in some Datsuns, the Fusible Link main power feed connects here)

* Big Terminal 2: Power to starter (big wire goes into the starter housing)

* Small terminal: To Ignition Switch "S" terminal

 

But the photo shows a possible mis-wire. The yellow connector will only be live during cranking, which is most unusual.

 

If those Yellow wires go to a Ford-type external starter relay, they are too small for the current.

[DanielC]

I agree you need to remove the not stock "previous owner" added wires. Nobody has any idea what they were doing.

 

Here is a link to a simple wiring diagram of just ignition, starting, and charging wires. It is for a 510, but that part of the electrical is pretty much the same as a 521.

http://dimequarterly.blogspot.com/2012/02/simplified-start-charge-wiring-diagram.html.

[wayno]

I agree you need to remove the not stock "previous owner" added wires. Nobody has any idea what they were doing.

 

Here is a link to a simple wiring diagram of just ignition, starting, and charging wires. It is for a 510, but that part of the electrical is pretty much the same as a 521.

http://dimequarterly...g-diagram.html.

 

 

Link doesn't work for me.

[ggzilla]

There was an extra period in the link.

 

Try http://dimequarterly.blogspot.com/2012/02/simplified-start-charge-wiring-diagram.html

[wayno]

According to the wiring diagram, I don't see how that even charges the battery, unless there is another wire in there I can't see.

[ggzilla]

You can put a wire from alternator straight to batter POS cable and it will work fine. Apparently the 521 didn't use a fusible link like all newer Datsuns and other cars.

[wayno]

You can put a wire from alternator straight to batter POS cable and it will work fine. Apparently the 521 didn't use a fusible link like all newer Datsuns and other cars.

 

 

I was/am looking at the light brown color of the main wire coming off the alternator, and the light brown color of the wire connected to what looks like the power supply to the starter motor, it seems like when the engine is not being turned over, that would be a dead end, unless the power can somehow go threw the brushes and get back to the post with the red wire that goes to the battery.

There is a blue wire connected to the positive side of the battery that goes somewhere?

[ggzilla]

What a mess :no:

[wayno]

I have to be missing something, it seems like the starter motor would be running all the time if that was the power supply to the starter motor with what looks like the alt. wire connected to it supplying power while the engine is running.

He says it's working now, so it's fixed.

[DanielC]

A stock 521 just hooks the positive output of the alternator to the big post on the starter that the cable going to the battery hooks to. On Ratsun, my project, I made a heavier gauge wire to do this. Here is a picture.

There should also be a black wire dropping down from where the negative battery cable attaches to the cylinder head, going to the frame of the alternator. There is also a second black wire that goes from the frame of the alternator, into the wiring harness, and this wire goes to a eye, that is under one of the bolts on the voltage regulator.

In my picture above, you will not see any of the other wires, because I had then tucked out of the way when I made the white wire you see.

[dat521gatherer]

Glad you got it working. Wiring issues can be a pain. Chasing down blinker problems, charging problems ect. This hasn't happened for a while but sometimes my 72 just looses power and dies then the power blinks back on and thats with new everything including fusebox

[DanielC]

"sometimes my 72 just looses power and dies then the power blinks back on"

 

Classic symptom of dirty battery terminals. Clean them.

Battery terminals are made of lead. Lead naturally oxidizes by itself, in a dry environment. Unfortunately, batteries have sulphuric acid in them, and even if the battery is sealed, a little bit of it gets around the battery terminals. If your battery cable ends are not lead, this makes the problem worse.

 

Normal maintenance on a car, ANY CAR, includes cleaning the battery terminals every so often. You sometimes have to replace the bolt that holds the cable end clamp, and even sometimes the cable. Any moisture, plus sulphuric acid, different metals, and electricity pretty much guarantees some corrosion is going to happen.

[dat521gatherer]

Yeah it's definitely not that. I only run corrosion free sealed type cables. I learned my lesson with the painted black and red terminals the hard way many years ago. I would trouble shoot it when it happens but by the time I get out the truck it's working again. Hasn't happened for a while.

 

I mean it could be and it's a connection problem somewhere but it doesn't give me any time to find it.

[ggzilla]

corrosion free sealed type cables

There is no such thing. The interface between the battery post and the cable end will still corrode. To prevent problems clean it about every 12 months. Or just wait until it won't start.

 

Sealed cable (cable end sealed to the cable) are very good, as the end-to-cable joint won't corrode. Datsun original equipment was a semi-sealed type. The worst are the bolt-on cable ends, but if properly treated they can work for decades.

[banzai510(hainz)]

I didint read this but going by the photo the fusable link wire feed to fusebox wire(round lug) is on the ground side of the starter. WRONG!!!!!!!!

that relay looks like a START relay circut. Pull one wire and if starter dont turn over then you know.

 

get a volt meter!!!!!!!!!

this is a EZ fix

[AcesHigh]

What a mess :no:

The wiring is a can of worms! When I installed the new starter, I wired it the way it was and after looking at the wiring diagrams, realized how screwed-up everything is, and moved the positive cable from the alternator to the correct terminal and FINALLY got14.4v! My haynes manual came in the mail today and I flushed the radiator fluid. Next step is the trans and rear-differential fluid change. Im going to look at the scheduled maintenance and see what needs to be lubricated. The work is rewarding though!

[mjja]

Where did you by the alternator?I have a 521 also I live in modesto California.

[banzai510(hainz)]

I got one from O rileys last month like 40bucks 35amper external volt reg type