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How to test an ammeter?

11508 Views 6 Replies 6 Participants Last post by  Kbeitz
The ammeter needle on my Wheel Horse 854 does not move at all. Turn on the switch and not a wiggle. Start the tractor, and not a wiggle. What is the best way to test an ammeter to determine whether or not it is functional? vvm.
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id also like to know this cause i got the same problom but i think mine just isent grounded
Put a test current to it and see if it reads right. Battery + to resistor, resistor to ammeter + post, ammeter - post to battery -. Note this means disconnecting the ammeter from whatever it's connected to originally.

Just be careful to use adequate sized wire based on the current and an adequate wattage resistor for the load.

Pick resistor resistance (in ohms) based on R = V / I.
V is voltage of your power source
I is the current you want (middle of ammeter's range should do)

Wattage of resistor (in watts) needs to be at least V x I or higher.

Another method is to insert the meter in series into a circuit of known amperage flow, such as a headlight feed, so long as the amperage doesn't exceed the meter's max range. Expected amperage of a lighting circuit is the bulb's wattage divided by the voltage across the bulb.

This is all for DC by the way...
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yeah, but the lights MAY be AC only. if so the meter won't work. easy way to tell if that is the case is to see if the lights work with the engine off. if they do, you cna use them to test the ammeter. simply turn teh key on but don't crank it. then turn the lights on. the meter should dip.
Obviously either the meter isn't working --or is incorrectly set up...I have several different models of Wheelhorse's and the amp guage goes over pretty far to the right when running @ WOT.......Then drops back to almost middle "O" when ideling........

Mine wasn't working at first on one of my C-models, and couldn't find one available locally, after verifying mine wasn't working---bought two off e-bay (brand new govt. surplus , still in bags) from someone out in Kansas....took about a week to show up--but they are OEM Danco brand like what came in them...
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Thanks for everyone's input. Was able to check it out and found it is stone dead. Tried the same test on another one, and it checked out fine using the same procedure. Had another old 854 fuel tank here with ammeter still in it, which will be put into the other 854. Like the old timer says, "you never know when those old parts will come in handy". vvm.
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