Farmall Cub

While hauling some wood around last night, the front headlights wouldn't come on. The night before, while plowing snow , I didn't have any problem. Nor have I had any problems since I got them working some time ago. I played with the switch knob, wiggled the wires in the back a little, checked the fuse, jumped the fuse but nothing on the easy side worked. Before I really get into it, thought perhaps someone on the forum might have a thought on it.

Thanks, Andy

I have found an automotive test light probe to be indespensible, along with both an analog and digital multimeter. the test light here would be the easiest (have to replace the light bulb if your system is 6 volts). simply clip the alligator clip to ground and the sharp point is meant to pierce the insulation if necessary (or get through rusty contacts).

before i start i check the test light on the battery. that insures that the ground i chose is good and the test light is operational.

check for 12 volts (light on) at the fuse and then at the connection going to the lights when you turn the switch on. no light at fuse plus = no power, no light at other end of fuse = bad fuse / connection, no light at switch output = bad switch (with the switch on, of course), no light at headlight = bad connection in harness, power all the way to the light and still no headlight? = bad headlight bulb OR (very important) bad ground on the light.

for trailer wiring and simple lighting circuits, this inexpensive little tool is unbeatable.

hope that helps.

How is your ground?
Mike

Hey ARTC, Your right! A test light is the best tool for that kind of trouble shooting. I use it more than a multimeter. A digital multimeter will lie to ya in descete power circuits because so little current is needed for them to take a reading. If you gotta use a meter at least use an anolog type rather digital. Last I checked antique tractors don't have intregrated circuits anywhere.

Thanks. It was, of course, something simple. I confirmed the lights work by jumping them to the battery. So I put the fuse back in and out a couple times and they worked- I assume I need to clean up the fuse contacts some. Unless I inadvertenly bumped something to make them work but I doubt it.

Mentioning the ground- wasn't the problem this time but it was the only problem with the lights when I first got them working. All three lights (I also have the rear headlight/tail light combo) did not work when I got the Cub. After I cleaned up the grounds/posts, they all worked, even the red tail light.

Andy