Go BottomJD4410 Tachometer stuck on 2000RPM
 | barrycan5
Join Date: Nov 2007 Posts: 1 Winnipeg, Manitoba, Canada 
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2007-11-23 148670
Just purchased a low hour JD4410 Compact Utility Tractor and when I turn it on, the tach immediately shows 2000 RPMs and will not change until I turn the tractor off when the tach returns to zero. The throttle works okay - the engine revs up or down as the throttle is moved up or down. The tachometer however will not move from 2000RPMs.
Any ideas on solving this problem !!
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 | kwschumm
Join Date: Feb 2003 Posts: 5764 NW Oregon 
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2007-11-23 148671
The technical reference manual is your friend :-)
The tachometer circuit is pretty simple. Pulses are sent from the P terminal of the alternator over a dark green wire to the instrument panel (X8 connector, terminal F). With key switch in run position, engine off, parking brake locked, and X7/X8 instrument panel connectors disconnected do these tests: Connector X8, Terminal A (Red wire) should measure battery voltage, if it doesn't test F5 fuse and see if voltage is there. Connector X8, Terminal F (Dark Green wire) should measure 0.04 volts, if not check that wire out to the P terminal of the alternator. Connector X7, Terminal A (Yellow wire) should measure 0.45 volts. Connector X8, Terminal D (Black wire) should measure continuity to ground. If that all checks out the instrument panel may be bad. If you have a way to measure pulses (scope, frequency counter, etc) it seems to me it would be reasonable to tee off the P terminal and see what the pulse data shows. If it varies with engine speed all the way to the tach the instrument panel is most likely bad. You could examine it for bad solder joints or burnt components before replacing it. ....
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 | earthwrks
Join Date: Dec 2003 Posts: 3853 Home Office in Flat Rock, Michigan
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2007-11-24 148675
KW, my blue's tach pegs to full RPM when engine off and I turn the key to RUN without starting it, then goes to zero. Is this an indication of bad things to come or normal? ....
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| kwschumm
Join Date: Feb 2003 Posts: 5764 NW Oregon
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2007-11-24 148684
EW, I can't answer definitively but my guess is that it's normal. Or maybe not. Where's that blue tech ref manual when I need it? :) ....
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