Electrical weirdness

I hooked up a water temp gauge.

Now when it's running, I get crazy, rapidly changing readings on two different multi-meters across the battery.

Engine off, 13.25 volts if it's just been running, 12.7-something after a few minutes. Normal, ...

I removed the alternator wire to rule out a bad voltage regulator. Same thing, ... crazy meter readings while running. Steady when not.

I removed the + wire from the water temp gauge. Same thing,...



All I can think of is I routed the sensor wire past the ignition wires and there's some kind of inductance going on??

Tomorrow I'll fire it up with the w.temp sensor wire disconnected at the gauge and see what happens.

Everything works though, including the water temp gauge.

you can not expect reasonable readings from a digital meter on these "noisy" tractors..............get an old analog meter!

(quoted from post at 22:39:47 05/12/17) you can not expect reasonable readings from a digital meter on these "noisy" tractors..............get an old analog meter!

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I've seen the meter hold a steady 14.48 volts while running before though.

If I hold the meter near the tractor, it goes nuts.

Just out of curiosity I went and got a florescent light tube and it was glowing in my hand when I held it near the engine block.

It takes high voltage to do that, so it's something in the ignition system.

I cut all the zip ties and pulled my low voltage wires away from the ignition wires. No change.

Ballast resistor and additional resistor are still showing 0.5 ohms (engine off, key off)

12 volt square can coil, was just under 3 ohms last I checked it.

When I probed the top coil terminal, negative clipped to alternator bracket, I was getting 8.9 volts, dropping a hundredth of a volt every second or two (probably the ballast resistor warming up). It should be about 6. The electronic points were closed. When I rotated the fan to close the "points" it went up to 12.7 something.



Thinking maybe somehow the square can coil self destructed itself and it's got too little resistance now, ... it shouldn't have been 8.9 volts at all.

Like maybe it's kicking out too many volts and the excess is "leaking" somewhere. I already caught it leaking out of the #2 terminal on the distributor today. It was running on 3 cylinders, I identified the dead one with the infrared gun on the exhaust manifold, looked at the distributor and it was arcing between the boot and the distributor body.

I put dielectric grease on that brass terminal, fired it up, no more arcing and all 4 cylinders are firing. The arc was damn near half an inch. And that was after getting through the plastic and the rubber boot.

I see no problem here. Just get on tractor & use it.