Unless there is some strange electronic control involved...
The light is a simple circuit, one terminal of the lamp is powered hot from the ignition switch. The other terminal goes to the regulator or alternator, depending on the system used. Look on the alternator for a name, like Autolite, Motorola, etc. Search "xxxx alternator wiring" and you can get a basic diagram of what's in there.
When the ignition is on, and the alternator is charging properly, both terminals of the light are powered equal, so the lamp goes off.
If the alternator is not charging, the power is not being returned to the lamp, so it would be on.
BUT, if the power from the ignition switch was not being supplied (as in a loose connection) the power from the alternator would feed back through the lamp and cause it to glow. If this is what's happening, look for corroded connections, especially if there is a plug together connection that is exposed to rain or near the battery. That lamp is also essential for proper charging, it "excites" the alternator to get it charging. If the circuit is not there, the alternator won't charge properly.
Usually the circuit that supplies the lamp will power other instrument related lamps and gauges. If other problems are showing up, they could be related.
Upload one or more videos to your post. Photo filesizes should be less than 300K and Videos, less than 2MB. Formats allowed are gif, jpg, png, ogg, mp4, mov, and avi. Be sure to use filenames without spaces or special characters, and filetypes of 3 digits lower case.
We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today. [ About Us ]
Today's Featured Article - New Life for an Old Allis - by Tyler Woods. My friend Jon, has an old '39 Allis Chalmers B. He thought it a marginal tractor that had long since served its time. She smoked terribly and never had much power but he couldn't afford another so he was limping along with what he had. Jon's Allis has a small front loader and though it doesn't carry much, it serves his needs. It was the hard starting and low power that made him think it was time to replace the old girl. Jon called me to help him discover why his tractor wouldn't start
... [Read Article]
Latest Ad:
Sell 1958 Hi-Altitude Massey Fergerson tractor, original condition. three point hitch pto engine, Runs well, photos available upon request
[More Ads]
All Rights Reserved. Reproduction of any part of this website, including design and content, without written permission is strictly prohibited. Trade Marks and Trade Names contained and used in this Website are those of others, and are used in this Website in a descriptive sense to refer to the products of others. Use of this Web site constitutes acceptance of our User Agreement and Privacy Policy
TRADEMARK DISCLAIMER: Tradenames and Trademarks referred to within Yesterday's Tractor Co. products and within the Yesterday's Tractor Co. websites are the property of their respective trademark holders. None of these trademark holders are affiliated with Yesterday's Tractor Co., our products, or our website nor are we sponsored by them. John Deere and its logos are the registered trademarks of the John Deere Corporation. Agco, Agco Allis, White, Massey Ferguson and their logos are the registered trademarks of AGCO Corporation. Case, Case-IH, Farmall, International Harvester, New Holland and their logos are registered trademarks of CNH Global N.V.
