12 v generator Charging system going crazy - need advice

1964 Farmall 140 with 12 volt generator system with external regulator.

Noticed generator wasn't charging so we grounded the field post on the generator to bypass regulator. Nothing changed and no movement st the ammeter, therefore we diagnosed it as a faulty generator.

Installed another generator from parts tractor
, polarized it, and it was showing a "discharge" on the ammeter. I reversed the wires on the ammeter and it started reading correctly and was charging well.

At this time I decided to replace the on/off toGGLE switch with a key style on/off switch like it had originally. I had one I picked up at tractor supply that was for the ford 600/601 series tractor that was an on/off style key switch. I hooked it up using the 2 wires that were on the toggle and didn't pay much attention to which wires hooked were.

We then preceded to reinstall the new battery and complete battery box. Once everything was all back together we noticed the amp gauge was all the way to the right and was "pegged out". We started the tractor and the meter started reading a "discharge" again!

We started investigating and found that the "Gen" wire (middle of the 3) on the voltage regulator was really hot. I started to unhook the "bat" wire ( the one by itself )from the voltage regulator and it was sparking when touched. Once that wire was unhooked the needle on the ammeter went back to the center.

My question is....does this mean I have bad regulator ?? I have a new one to install but would like to know before I try and possibly ruin it. Could it have been something I did prior?

First of all, do you have a 3 terminal (BAT GEN FLD) or a 4 terminal (BAT LOAD FLD GEN) Voltage Regulator??????

On most 4 terminal VR's the GEN/ARM is off on one side or underneath all by itself. The three terminals side by side are BAT LOAD and FLD. SO INSURE WHICH YOU HAVE AND THATS ITS WIRED CORRECTLY

BAT to load side of ammeter
GEN/ARM to Gennys ARM post
FLD to gennys FLD post
LOAD sends hot battery voltage up to switch

Has polarity been changed on the tractor?? if the ammeter is wired correct when you turn on lights or ignition engine NOT running it should swing over towards - discharge, then when started at fast RPM it should swing to + charge IF GENNY WORKS AND METER IS WIRED CORRECT. If it does the opposite its wires need swapped.

If the batetry voltage is around 12.6 when shes setting but at fast running RPM it rises to 13 to 14 or so THE GENNY IS WORKING even if the ammeter isnt or is wired bass ackwards reading the opposite

If she charges fine when you dead ground the gennys FLD post but NOT otherwise, that tells you the Genny itself is okay so the problem is EITHER The VR is bad,,,,,,,,Or the VR isnt well grounded (try that first),,,,,,,,Or the wires bad or open or mis wired from FLD on Genny to FLD on the VR

If when you turn the tractor off theres a high current discharge, the VR's Cutout Relay is sticking closed

Run my Troubleshooting procedure, it will tell if the Genny or VR is bad

http://www.ytmag.com/cgi-bin/viewit.cgi?bd=jd&th=458743

John T
John Ts Troubleshooting Procedure

How did you polarize it? Sounds like something is backwards.

(quoted from post at 21:40:08 04/14/13) How did you polarize it? Sounds like something is backwards.

Click to expand...

We jumped the middle terminal on the regulator and the terminal all by itself. We were hoping that those were the batt and gen terminals but couldn't find any markings on the regulator. I used a new replacement regulator as a reference for which posts were what. I didn't confirm the regulator was wired correctly. I will have to look.

It is a 4 terminal regulator

Follow John's instructions and pay particular attention to his point of making sure battery polarity is correct. IH switched to negative grouind and 12 volts in mid stream on those model tractors if the parts book is correct and I believe it is. So, if ammeter reads charge with lights on and engine not running you know either ampmeter is hooked wrong or battery ground polarity is wrong. Also, on a four terminal regulator, the single wire on one side is generator armature wire and not battery.

Thanks guys.....a new 12 volt regulator and switched the wires on the ammeter did the trick!