PM260Z PTO shut off while mowing and now won't start

fmorelli

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Kinda scanned over the post didn't see what kind of mower this is on. That can make a difference. I recall several years ago the Kohler had a problem with the bottom main bearing due to the electric pto seeking ground and it would wiped the bottom main bearing out. Old model mowers with only one wire (hot wire) to the clutch it could do this. Is this mower that old? if the clutch windings shorted to ground it could this. Before you put a new engine on the mower I would find out why this happened. Would hate to see you ruin a new engine. Some mower manufactures put a diode in the pig tail or the wire before the pig tail. To stop the voltage spikes that a electric clutch can generate.
2005 Gravely PM260Z 992047 first gen production (00101-01499).

Mine does seem to have the diode inline, but I can confirm.
 

fmorelli

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Ok ... decided I should dig into the electrical system some before going any further. I could use a second opinion or two on what I'm finding. The summary is that my 2 year old PTO switch seems to not be happy.
First I unplugged the diode and tested with multimeter ... tests as a one-way valve should.

Next I went after the PTO switch. Mine has 5 legs. Let me first post some pictures, then I'll say what I found:

PTO switch.jpeg

plug face.jpg

plug wires.jpg

wiring diagram.jpg
 

fmorelli

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Ok here is what I found, using above images. Paper diagrams are from original factory manuals that came with the mower when I bought it. On the PTO switch ... 3-9 works as shown in the diagram - continuity when disengaged. I'm not sure what the deal is with the numbers swapping in the "1 4 7" posts (maybe factory typo) but nonetheless NONE of those posts show continuity, whether the switch is engaged or not.

I provide photos of the wiring harness so we have all the information directly in front of us. What confuses me is the wiring diagram that shows the PTO switch (last photo). It is a 4-wire configuration, but it seems to me the PTO switch physical diagram does not map location-wise to the 4 prongs on the back of the switch. On the other hand the wiring color lines up perfectly, so unless I am reading something wrong I'm going to run with the wiring color on the diagram.

I suppose my question, assuming everything above is on point - if the "1 4 7" leg never shows continuity, what would I expect the mower to do? Thanks all for any insights!
 

fmorelli

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Working on reassembly and will provide a full report once I'm done.

When installing the sheave (pulley) for the hydro belt, on the crankshaft, the pulley is asymmetric (taller offset on one side). I've dug through Gravely and Kohler manuals and cannot find anything that confirms the orientation. Is the fat side of that pulley offset toward the engine or toward the PTO clutch? Thanks!
 

fmorelli

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hlw49

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Put the sheave on the engine and the belt and see how it lines up with the pump pulleys.
 
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