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light switch problem

F

Fuller's Farmall

New User
I am having problems with my light switch. When I am running the tractor and turn my lights on it goes to the -20 amp charge. It has the 6 volt system and a magneto.
 
First, the magneto will have nothing to do with the problem. There are various possibilities.

1). Poor contacts in wiring system. Check all contacts, especially for generator and voltage regulator (or generator High / Low charge switch).

2). Dead short. If the lamp circuit is fused the fuse should blow instantly. If not, wiring will become very hot quickly and begin to burn.

3). Defective winding in voltage regulator (if fitted). Test regulator and cut-out operation. Generator should cut in at about 6.5-6.8Volts and cut out at 5.5 Volts. With generator at full speed it should show between 7.5 and 8.1 Volts. At 70 deg. F. it should show 8 Volts.

4). Defective field winding in dynamo. Check for short circuit or low resistance between field terminal and Earth.

5). Defective ammeter. Test system with another ammeter.

6). Defective battery. Test battery.

Do you have a wiring diagram?
Does the system appear to charge normally with the lights switched off.
Can e-mail wiring diagrams and test diagrams if you need.
 
I think I would unhook the wire on the light switch that actually leads to the lights and then see what happens if you turn them on??? If that cures the problem theres a pretty bad short in the lights wiring.

If the lights are NOT on what is the ammeter showing??? If it charges then the genny is likely okay.

Is it a LHBD switch and a Cutout Relay ??? Or and Off Bright Dim switch and a full fledged Voltage Regulator ???????????????

If you run my Troubleshooting Procedure linked below it can help diagnose non charging problems but you really need to se if theres a short in the lighting circuit (wirign and lamps) FIRST.

http://www.ytmag.com/cgi-bin/viewit.cgi?bd=farmall&th=665110

John T
John Ts Troubleshooting
 
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