Externally regulated new alternator/regulator/ammeter wiring (1 Viewer)

[JohnJL]

I am finishing up a restomod of a 1974 FJ40 and got the rebuilt motor running for the first time today. I noticed the alternator is not charging while running. I initially wired the alternator with a shunt to the stock gauge, and that complication may be one reason its not charging.

So I am going to simplify everything back to its bare minimum using the stock ammeter in the gauge, new 60 amp externally regulated alternator and new OEM regulator.
The wiring harness is all new so I can do anything I want here...

One question I have is regarding the alternator wiring itself. Here is a pic of the alternator with the cast markings in RED.

The alternator is marked with the 3 spade terminals E F and N. It also has a ring terminal marked B. I have that B terminal on the alternator going to my battery + terminal.

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The wiring diagram shows a B, F and E but no N on the alternator.

On a stock 1974 is there no connection to the B terminal on the alternator? And what is that N terminal on my alternator?
Here is the wring diagram I have, with the green and red traces for the ammeter wiring as I will now connect and see if my no-charge situation is fixed.

So do I follow the wiring diagram and ignore the N terminal on my alternator?

Just for good measure, here is my regulator. It has a blue (for capacitor,) white/red which looks like it should be connected to a fused 12v source, a white/black to the E terminal on the alternator, white/green to the F terminal on the alternator.

So what about that N terminal on the alternator? And the B ring terminal?

Thanks!

 

[JohnJL]

I found this from Rudi...so the N is left not connected on the alternator, and the B on the alternator is routed to the gauge ammeter per the wiring diagram above? God that seems weird to send that alternator current unfused to the gauge...

 

[pb4ugo]

You should have a fusible link at your battery connection.

 

[JohnJL]

Found this one from Rudi too on this thread: No N on the alternator.

 

[1969FJ]

Found this one from Rudi too on this thread: No N on the alternator.

Apparently, the "N" was just to bias a lamp under some condition. So, you are fine following this schematic.

 

[JohnJL]

Apparently, the "N" was just to bias a lamp under some condition. So, you are fine following this schematic.

Thanks. However that diagram doesnt show the Ammeter....so I am guessing I will start with reverting back to B from the Alternator, through a 50 amp fuse to the gauge cluster, then from the other side of the gauge cluster to a 50 amp fuse to the Battery +?

 

[JohnJL]

Well I wired it (mostly) according to the factory diagram as highlighted here but I blow a fuse for the ignition coil and gauges when the key is in RUN.

I will recheck my connections to be sure I dont have any shorts in the morning. Before changing the alternator wiring the truck started and ran with no fuse issues, except the alternator wasnt providing a charge very likely due to my overly-complicated wiring attempt to reroute the higher current out of the dash area. Two questions come to mind;

1. The IGN connection on the voltage regulator (#14 above) goes to the hazard switch from fafctory which I assumed to be 12v+ and out of convenience connected the regulator IGN to another 12v switched source, in this case the ignition circuit which is what is tripping. I found this post from Rudi on another thread which I took to mean the IGN could have any swithed 12v but that is now tripping.


>>>>>>
On the VR you'll find 3 wires.
* Red/Yellow stripe (on some models Black/Yellow stripe). This is the IGN wire that should be 12V when the key is in the ON position.
* White/Green stripe. This is the Field wire. This wire should be around 12V as long as the battery is below 13.6V.
This wire "regulates" the output from The alternator.
* White/Black stripe. This is the ground wire. Not important at this moment.

If R/Y is not 12V you have a wire problem between the "engine" fuse and the VR. Maybe a bad contact if you're lucky.
If R/Y is 12V but W/G is not 12V you have a defective VR.
If W/G is 12V, and still no output on the alternator........you have a defective alternator.

Rudi
>>>>>>>>>>>>>>>>>>>>>>>>>

2. I suspect #1 is a problem and hopefully I will figure that out. My second question is whether I have the correct regulator for this alternator. I ordered both at the same time from SOR. The alternator has an N which I think I have learned can be used with a 6-pin alternator. Can this alternator be used with the 3-pin that SOR sent?

#3 Finally, I dont have the old condenser that was on the old regulator. I understand that to be for electronic noise supression. If I dont have it, should that blue wire be grounded, left unconncted, or must I find a condensor somewhere?



Thanks!

 

[JohnJL]

I found this old pic from before tear-down, it looks like the old alterator also had but didnt use the N terminal on the alternator. The wires as you can see were already aftermarket (painless.)

 

[JohnJL]

So I will just finish off this conversation with myself here, perhaps it helps someone...

1. Ignition fuse blowing: This stopped when I removed the blue wire on the voltage regulator from ground. I am missing the condenser and connected the blue wire to ground. When I removed and taped off the blue wire I stopped blowing a fuse.

2. Once I removed the blue wire from ground everything worked. The truck is now wired as described in the wiring diagrams above. I keep a book of the modifications to the wiring. I get 13-14v idling and the ammeter appears to be functioning correctly. I'll still experiment and tidy everything up but at least I have a known baseline and knowledge everything works. And no smoke ;0)

3. Do not ground the blue regulator wire. Connect it to a working condenser or leave it taped off.

 

[Kschep]

Good stuff - I’m finding fault in mine right now and I’ll go straight to check if the previous owner grounded that blue VR wire ... thx for finishing that off!

 

[Steamer]

Grounding Alternator case? N terminal?​

 

[Pin_Head]

Well I wired it (mostly) according to the factory diagram as highlighted here but I blow a fuse for the ignition coil and gauges when the key is in RUN.


1. The IGN connection on the voltage regulator (#14 above) goes to the hazard switch from fafctory which I assumed to be 12v+ and out of convenience connected the regulator IGN to another 12v switched source, in this case the ignition circuit which is what is tripping. I found this post from Rudi on another thread which I took to mean the IGN could have any swithed 12v but that is now tripping.



Thanks!

The ignition coil is not fused for safety. You don’t want to lose engine power while you are driving.

The VR should get power from the engine fuse, which is unrelated to the hazards. You must be reading the schematic wrong.