Charging Tests Photos

Sun Jul 29, 2012 9:19 am

These tests shown here are for a Cub 6 volt Pos. ground generating system with regulator. They may work with other systems but care needs to be taken. Even polarizing some systems is different and if done improperly the regulator can be shorted out.

I’ve set up these tests to basically correspond with the flow chart that is often referred to and posted on this site. ( Find it here. download/file.php?id=9047&mode=view )This may or may not be the best way to test but I figure it is some thing we are all familiar with. Also doing it this way you don’t have to have a meter, but it would be helpful if you suspect or you determine that the gauge is the problem.

One thing I’ve noticed in my experience is that it isn’t uncommon for an AMP gauge to work in one direction and not the other.






I may be editing this and the schematic tests. I had thought of something in the middle of the night that could be of help, but now I don't remember what it was.

Re: Charging Tests Photos

Sun Jul 29, 2012 10:39 am

I've run into several instances, where the amp gauge worked, for discharge, but not for charge, when the system was charging. Ed

Re: Charging Tests Photos

Sun Jul 29, 2012 11:29 am

A lot of ammeters don't "zero" at zero. For example, you look at it with everything shut off (or even disconnected) and it might show 2 amps of discharge. You start it up and the needle moves to 0, which means it is charging about 2 amps. It needs to charge more than 2 amps to show positive on the meter.

Re: Charging Tests Photos

Sun Jul 29, 2012 9:48 pm

Thank you for all the work. It is very timely for me, as I've just re-assembled my 51 cub, and cannot get it to start. It was running perfect before the tear down, and while apart, I repaird the wiring harness. A few of the wires were bare, just the two running up to the generator, and the one from the coil to the distributor, so I made up new ones for those. One at a time, so nothing was changed. Also the headlight wires were shot, so I made up a new harness for them as well.

The wiring harness was not too bad, so I removed the outer brade, and shrink wrapped the whole thing, and it turned out nice.
Again, the wires that were taken loose at the voltage regulator, I tried to mark and replace where they were to go, but in the middle of it I realized a tag fell off and I lost track of the Bat and L wire for the regulator. I'm farily certain I got it back correctly, but we'll move on for now. Below is a pic of the wiring harness:


So, I got her all back to gether, and she looks beautiful. Hooked up the battery, turned on the gas, and she cranks and cranks, but no start. Did a bunch of troubleshooting today, and I'm not getting any fire to the distributer. With the cap and rotor (plate) removed, I do not have any spark at the breaker points.

Did some more troubleshooting, and here's where things get odd.

This is a 1951, original wiring harness, 6-volt, + ground,
Headlights work with the push/pull iginition switch in or out. - unsure if ok
Starter cranks fine - ok
Continuity from batt wire on regulator to starter - ok
Ammeter shows slight discharge when headlights are on or try to start - ok
No continuity from L terminal wire on regulator to on/off switch - ???
Continuity from on/off switch to Coil - ok
Continuity from coil to distributor - ok
On/off switch shows continuity while pulled out and when pushed in - ???

My big question now is - how can the headlights work if the L wire has no continuity back to the on/off switch? Also, why do I have continuity across the on/off switch regardless if it's on or off?

I did find that I did in-fact have the batt and L wires reversed on the voltage regulator, and have corrected this. However, I have the exact same conditions as before I corrected it (as noted above).

At this point I'm thinking that the L wire must have broken at some point in time and someone has jumpered it behind the dash in order to get power to the lights. I did not have the dash off when working on the tractor, as everything was working fine, so I figured there was no reason to mess with it. I did move the wiring harness around A LOT! while working on it, so it's increadibly possible that I pulled some thing loose in there.

I think I'm going to pull the dash loose and see if I can move it out enough to get a hand in behind it and see what is up. I'm hoping to not have to pull the hood again, since I just put it all back together, but that's probably going to happen isn't it.

I'm open to suggestions. Based on the L wire issue however, and power to the headlights, I'm still not certain why I have no spark at the distributer?

Thanks again,

Here is a picture with the hood on it, but unfortunately, it may be coming back off to work on the wiring:


Re: Charging Tests Photos

Sun Jul 29, 2012 11:46 pm

With all that beautiful new paint could you have grounding issues with the ignition system?

Re: Charging Tests Photos

Mon Jul 30, 2012 6:27 am

I don't think there are any ground problems. Most everything checked ok to ground or showed voltage to ground.

Re: Charging Tests Photos

Mon Jul 30, 2012 7:31 am


Headlights work with the push/pull iginition switch in or out. - unsure if ok

That's correct.

No continuity from L terminal wire on regulator to on/off switch - ???

This may be where your problem is but not for sure. Some one may have rewired it taking the switch power from some where else. Possibly from the starter, AMP gauge, light switch or even elsewhere. Although the light switch should get it's power from the ignition switch.

On/off switch shows continuity while pulled out and when pushed in - ???

This is not right, it could mean the switch is bad but I'm thinking the way you describe the problem that some thing is wired wrong.

When you say you have continuity I'm assuming you are testing with an OHM meter, not with a test light or volt meter. If this is correct you need to test for voltage. having continuity doesn't tell the hole story, it just tells you that the wire is good.

Nice looking tractor, by the way.

As danovercash said it could also be a ground problem, but that wouldn't explain the switch problem.

Re: Charging Tests Photos

Wed Aug 01, 2012 7:40 am

Thanks for the help guys. Turns out, after thinking about it a bit, I realized the issue. Went out and checked and had continuity from the "L" wire to the headlight switch :shock:

Checked the headlight lead, and had continuity from the headlights to the iginition switch :shock:

FOUND! I had switched the L and headlight lead. Didn't need to take the hood off :D and was able to remove the voltage regulator, then reach under the hood, clip the headlight lead, unsolder the terminal for the VR, swap it to the old headlight lead, crimp the old L wire to the headlight harness, and whala she fired right up :{_}: :{_}: :{_}: :{_}:

Luckily, I didn't do any apparent damage to the VR, as she shows slight discharge at idle, and charge at 2/3 throttle, so everything seems to work. Also, this fixed the wierd On/Off switch continuity. I think I had a loop to the switch previously, which is why it showed continuity all the time on or off. Working perfect now!

My internet is down at home (working from Dunkin Donuts now) so I'll update with the final finished photos later this week.

Re: Charging Tests Photos

Fri Aug 03, 2012 10:17 am


I like this one as well. Wonderful work you are doing on these electrical teaching aids you have been doing. Some of the best explanations I have seen in a long, long time making it much easier for many of us to learn and retain this kind of information :!: :-:-): :D