Charging Problem

[Dat521sun]

46 minutes ago, DanielC said:

Start with this.   This is for a 1970 521, but there were changes in 521 wires.  Earlier 521 trucks, even with L-16 engines had a three always hot fuse box, later 521 trucks had a four always hot fuse box.  The extra hot fuse in the later trucks was to separate headlight power to the light switch from tail light and marker light power to the fuse box.

 

On a stock 521 the positive battery cable goes to the starter solenoid, and there is a fairly thick wire from the starter solenoid to the positive out terminal on the alternator.  There is no fuse, or fusible link from the positive alternator post to battery positive.  There is a pigtail wire from the positive battery terminal to the fusebox, and at the fusebox a white wire then goes into the cab, and to the ignition switch, again with no fuse, or fusible link.  Ignition key switched power comes from the ignition switch on a black wire with a white stripe, to the battery side of the fuse box.  A second black wire with a white stripe goes to the ignition coil, from the battery side of the fuse box.   Power to the ignition coil is also not fused.

The instrument cluster is fused, getting power from the white wire coming from the ignition switch.  Fused power is also supplied to the voltage regulator, from the black wire with a white stripe.

 

There is nothing that should be making a ticking sound in the alternator, or behind the dash near the key, on a stock 521.

 

You should be able to start and run the truck without any fuses in the fuse box, I even ran one of my 521 trucks around my farm without a dashboard, or instrument cluster. 

 

If you have an internal regulated alternator, you can start and run the truck without the "T" plug in the alternator, and it probably will not charge, but it could start charging if you rev the engine.   With the truck running, you can use a test light hooked up to positive battery terminal to touch the "L" terminal on the alternator, and that will cause the alternator to start charging.  the terst light will briefly flash, and then stay out.

 

 

I read your post, for the dragon 521, that's why I made the fuse box, followed your instructions. Same way to removed the amp meter, you explained how to install it, I just went backwards and removed mine(previous owner made a mess with the wires) 

 

I just bought a Pathfinder alternator to match your post and fix this charging mess in my 521

 

I'll do the test light to the "L" terminal tomorrow morning. 

 

Thanks 

Edited December 28, 2019 by Dat521sun

[DanielC]

In my last post, I mentioned that you can take an internally regulated alternator, and without the T plug plugged in, and the engine running, you can use test light from the positive battery terminal and touch the "L" witht eh teat light probe, and cause the alternator to start charging.

You can confirm the alternator is charging by checking the battery voltage, it should be 13.5 to 14.5 volts.

 

The IGN and OIL light in the instrument cluster both get power through the fuse box, on one of the switched hot fuses.   The two lights are not grounded in the instrument cluster, or the cab.  There are two wire connections, one to each light.  The OIL light is grounded at the engine, by the oil pressure switch.   When the oil pressure build up, the switch inside the oil pressure switch is opened, and the OIL light goes out.

The IGN is grounded by the voltage regulator on a 521 with an externally regulated alternator.

If you put an internally regulated alternator on a 521 engine, the alternator takes over the function of grounding the IGN light.  There is not a switch inside the alternator, the electrical circuit just grounds the light, until the alternator starts turning, and making electricity.  The alternator then applies charging volts to the "L" terminal, and since the IGN light in the instrument cluster now has voltage on both sides of the lamp, it goes out.

 

It is a really good idea to have the IGN light working normally.  If you lose a fan belt, the IGN Light coming on will be your first indication that something is wrong, before the engine starts to overheat.

 

Do not let your Datsun L-engine overheat under any circumstances.  It warps the head, and causes you to have many problems, including possibly having to pull the engine, and having it rebuilt, with parts that are getting harder to find.

 

Edited December 28, 2019 by DanielC

[Dat521sun]

Autozone kept selling me the wrong one(system says external regulated but they are internally regulated). They took it back and gave me my money. Ordered one from rockauto.com I'll keep you guys posted. 

Edited January 2, 2020 by Dat521sun

[dat521gatherer]

I had a similar problem with our 79 corona alt. Oriellys sold me a external regulator alt when I needed a internal regulator alt. I ended up eating the cost for waiting too long. Went to napa and got the correct one. Now it works.

 

The guy at the counter of Oriellys assured me the alt he sold me had a reg on the inside. There was no visible reg on the outside of the alt. That was a red flag for me but I trusted him anyway. Lesson learned.

[datzenmike]

 Nissan switched all Datsuns to internally regulated for '78.

 

The 620 external alternators have a removable black plastic dust cover on the back with slots cut in it. The internal regulated alternator '78 and '79, are all cast aluminum

[banzai510(hainz)]

mike you say 620 but I have had alternators with out the black plastic  and were exteral VR type.  early 610 and 710s I think 50ampers

 

Now with O rileys bring in different cases they don't even have the b;ack plastic on the back the last few I got. Just got to trust the part store.  My Rockauto "Power Select" brand is working fine

[Dat521sun]

Just finished installing the new alternator from rockauto.com, ign light came up as normal and the off. But I was getting low voltage, 12.40 at idle, and 12.16 revving. Then, ign light came back one. Decided to do a test running a wire from fuse box to alternator to check. No I'm getting 13.76 at idle.

Problem is that I'm over 17.09 when revving. I'm guessing I have a bad wire in the wire harness and I need a new voltage regulator. 

 

Any suggestions? 

[mainer311]

Can you take a picture of how you have the alternator hooked up?

[mainer311]

It should look like this. Large charge wire hooked to the battery via the solenoid post on the starter (like I mentioned in my PM), stock harness plugs into the “T” connector with those 2 yellow wires, and then there’s a large ground from the harness, which I also jumpered to a large ground to the engine block.

 

Edited January 4, 2020 by mainer311

[datzenmike]

On 1/3/2020 at 6:25 AM, banzai510(hainz) said:

mike you say 620 but I have had alternators with out the black plastic  and were exteral VR type.  early 610 and 710s I think 50ampers

 

Now with O rileys bring in different cases they don't even have the b;ack plastic on the back the last few I got. Just got to trust the part store.  My Rockauto "Power Select" brand is working fine

 

I have diagrams showing this but only the 620 and late 521 and called a brush cover but the 510 have the same thing called a diode cover. These are small alternators with low output.

[banzai510(hainz)]

Dat521sun said,his output wire of the alternator didn’t have 12volts. it should be hot all the time. So I told him to look into that but jumperwd the +alt to the battery then got 17volts revel up showing the its unregulated output of the alternator with a load with lights on.

but he had popped the solid state VR but don’t know if that white wire wasn’t really hooked up aa it’s not Hot. My 521 the +alt is white with red stripe .told him to put the ext mech VR

 

[mainer311]

That white wire with red stripe is too damn small. I replaced it with a nice piece of 6awg straight to the starter solenoid post. It also contains a fusible link just in case.

[datzenmike]

While I agree with a larger gauge depending on the year they are only 33 or 35amp output. I'm running 3 X that and the power wire on the alternator was larger than the stock battery cables!!! I did the same and joined to the starter.

[banzai510(hainz)]

Ok page 188 in the Haynes manual shows the out put of the alternator as WR (white w red strip) I will assume the red wore off. This wire goes up to the VR as the White wire. So I would ohm out that wire.Get a ohm meter from the output alt wire to the white at the VR and see if it’s good. I bet the wire splice is loose or broken under the tape if loose one could maybe move the wires around and it might work or just leave the ohm meter on there when truck is off and see if you get a short as it should be.

 

Dat521sun when you put a wire from alt out to the battery you got the 17volts but if that wire is open it’s not going to the VR I assume.You more or less bypassed the VR( I might be taking a educated guess on this 

hope this don’t confuse you more but that wire (white or white red)not being Hot is a big clue. This wire goes to the VR.so make sure it’s good.

[mainer311]

It should just be white. See the left hand side of my picture. I jumpered that on the solenoid post as well.

[Dat521sun]

***Update*** got it, after so many tries, back and forth, the whole problem was a bad starter. I replaced the starter and everything worked like it should, running strong. Was lazy the whole pandemic and kept the truck parked, now my rear brakes are locked 😆 I apologize for taking this long to update. Thanks for all the comments and help.

[Stoffregen Motorsports]

Locked brakes? As in stuck from rust?

[datzenmike]

E brake cables.

[banzai510(hainz)]

On 5/25/2022 at 7:39 PM, Dat521sun said:

problem was a bad starter.

what????????

[datzenmike]

Only way the starter could be the cause of poor charging is if it is wired this way with the sense wire connected to the starter....

 

 

And you don't need a new starter, it was probably just making bad contact and replacing the starter caused a better contact to be made.

[Stoffregen Motorsports]

If a starter is severely worn, it can crank slowly and one could easily assume that the battery is low.

 

Oil soaked starters are always suspect in my book.

[mainer311]

19 hours ago, datzenmike said:

Only way the starter could be the cause of poor charging is if it is wired this way with the sense wire connected to the starter....

How do you figure? It’s connected directly to the positive battery wire on the same post?

[Dat521sun]

On 5/27/2022 at 7:51 PM, Stoffregen Motorsports said:

If a starter is severely worn, it can crank slowly and one could easily assume that the battery is low.

 

Oil soaked starters are always suspect in my book.

I had a slow crank, usually smoke from solenoid. 

Edited May 29, 2022 by Dat521sun

[Dat521sun]

On 5/26/2022 at 12:04 PM, Stoffregen Motorsports said:

Locked brakes? As in stuck from rust?

The piston in the wheel cylinder made a nick in the housing preventing the piston to move back. Replaced the wheel cylinder. Replaced old brake shoes (they came off of the lining) now new brake shoes seems bigger, can't get the drum in. Adjuster assembly all the way in, still won't fit.

[mainer311]

I had the same problem recently. The lining is too thick. To solve it, I had to grind the ends of the shoes where they contact the slave on top, and the adjuster on the bottom.