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how do you test an electric tach
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grinder220 View Drop Down
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Joined: 11 Jan 2012
Location: Clinton Iowa
Points: 2372 		Post Options Post Options   Thanks (0) Thanks(0)   Quote grinder220 Quote  Post ReplyReply Direct Link To This Post Topic: how do you test an electric tach
    Posted: 06 Sep 2016 at 9:00pm
The 7040 I recently purchased has a non working tach, how do I test it to make sure thats the problem and not the alternator or the wire leading to it? I don't want to replace it just to find out that it wasn't broke.
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Tcmtech View Drop Down
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Joined: 15 Apr 2015
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Points: 310 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Tcmtech Quote  Post ReplyReply Direct Link To This Post Posted: 06 Sep 2016 at 11:25pm
If you have an old wall wart power pack  that puts out 6 - 12 volts AC, not DC, you can feed it to the tach signal and ground while feeding the tach 12 volt power off an other power pack or battery.  

If the tach jumps up to a specific RPM reading and stays there its working fine. 
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Play Farmer View Drop Down
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Points: 732 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Play Farmer Quote  Post ReplyReply Direct Link To This Post Posted: 07 Sep 2016 at 5:13am
Just run a jumper wire from the alternator directly to the tach. If it works, run new wires. If it doesn't it's probably the tach.

Having just gone through this with my 7000, I'm guessing it's probably the wiring.
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OhKen View Drop Down
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Points: 242 		Post Options Post Options   Thanks (0) Thanks(0)   Quote OhKen Quote  Post ReplyReply Direct Link To This Post Posted: 07 Sep 2016 at 6:56am
Before doing anything , make sure your connection to the alternator is good . Mine wasn't working either and I thought the problem was the alternator after having my rebuilder go thru the alt he assured me it was putting out the proper signal . Reinstalled and tach still didn't work and alt was working sporadically . After consulting with the rebuilder and posting here , I replaced the female spades in the alt plug . That turned out to be the fix for me . The old spades looked OK but in fact were not making the necessary connection . Tach now works perfectly , as well as charging system .
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charlesbendal View Drop Down
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Points: 92 		Post Options Post Options   Thanks (0) Thanks(0)   Quote charlesbendal Quote  Post ReplyReply Direct Link To This Post Posted: 07 Sep 2016 at 7:08am
Take your alternator to a good rebuild shop and have it checked if they charge for just a check it won't be much
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