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pto on the ztr popped out of gear

Posted by tom_nwnj z6 NJ (My Page) on
Thu, Jan 10, 13 at 6:46

Have a large ZTR mower. At end of this past season, the PTO popped out of gear twice. Was mulching leaves, quite a few were on the deck, in the pulleys.

Electric clutch.

Anybody know what that is? Is there an adjustment for that?



Follow-Up Postings:

RE: pto on the ztr popped out of gear

Sounds like one of those hard to find electrical problems to me. Bad connector, wire short, safety switch failing, etc. The only electric clutch adjustment will not affect staying engaged.

Walt Conner

RE: pto on the ztr popped out of gear

Are you having ANY other electrical issues, such as having to jump start it etc.???

RE: pto on the ztr popped out of gear


Yes, have problems with the "dead man" sometimes. Seems the parking brake is VERY sensitive. Local auto parts guy says battery is fine, well over 600 Cold Crank Amps.

RE: pto on the ztr popped out of gear

"Yes, have problems with the "dead man" sometimes. Seems the parking brake is VERY sensitive"

Either of these can cause a monetary break in the Safety Circuit causing the electric clutch to disengage.

Walt Conner

RE: pto on the ztr popped out of gear

We still have absolutely no idea what brand/model it is to see if there is an electrical schematic for it.

Kind of hard to give any advice other than check connectors & switch adjustments.

RE: pto on the ztr popped out of gear

Bill, the mower is a 2005 Lastec 3696.

Some guys have a used low mileage 'vette in the garage for weekends, or a couple of Harleys.
I have this almost three years now. Bought it used on Ebay @ 500 hours. Price was the balance of the bank loan + shipping.

RE: pto on the ztr popped out of gear

I tried to look at the schematic and simply can't make heads or tails out of it.
I thought there might be an obvious relay, but I'm stumped.
About all I can recommend is to clean the connectors in that circuit.

RE: pto on the ztr popped out of gear

OK, we're heading in the right direction now.
tom_nwnj, please post the serial number of the machine you have. I went to the website and looked at a couple of wiring schematics. It appears Lastec has in fact made some changes in wiring and safety interlock philosophies over the years.
One thing in particular I noted was one model has a "Blade Shutdown" circuit that is activated if the coolant temperature switch (engine overheat) closes.
I suppose Lastec intended this to be a twofold feature.
The overheat switch turns on the overheat indicator light and stops the blades when the switch closes. This would serve to alert the operator of impending doom as well as to lessen the engine load and thereby bring the coolant temperature down.
It might be a long shot in your case but I see (in the schematic) where a defective temp switch or a short in the wiring in that circuit might cause the blades to disengage.
Either of those conditions would also cause the overheat light on the meter panel to illuminate as well......provided the bulb is good.
The wiring schematics are "serial number sensitive" so a serial number will be needed to home in on the correct diagram.
I was thinking "Wow, that is a big battery", until I found out what it is in.

RE: pto on the ztr popped out of gear

Mine is the 3696M (Kubota diesel)
Serial Number 25850207

As mentioned, the PTO popped out when there was a lot of leaves on the deck. Have to wonder if that contributed to an "overheat" situation.

I have deck guards on the belts, but I think they unofficially recommend taking the deck guards off when mulching leaves.

Thanks so much.


RE: pto on the ztr popped out of gear

OK, I'm with Bill on this being one of the "poorer attempts" at making a logical wiring schematic by an OEM. Your mower wiring is covered on pages 5-14 through 5-16 of the owner's manual.
For sure, your mower does in fact have the "blade shutdown" when overheat occurs.
I will continue to study the wiring diagrams in hopes that the eureka moment might visit me (insofar as deciphering that mess).
I wonder if you know whether this machine does a "self test" or "bulb check" when you first turn on the key switch.
If it does perform a self check.......look for the overheat lamp or coolant lamp to light up briefly when you turn the key switch to the RUN position (initial key on event before starting the engine).
I DO NOT see anything in the wiring that specifically suggests it does the bulb check, but I do see some elaborate circuitry in the meter panel schematic which shows an alarm delay module and some other stuff which may perform an initial bulb check.
The point here is that unlike the engine oil pressure switch [which is always closed (if working) when the key is ON with engine off], the coolant overheat switch has to actually sense overheat temperature before it will illuminate the dash warning lamp. Checking the health/condition of the oil light bulb and circuit is easy, you just turn on the key and the oil light should burn before you start the engine. If it does not burn, then you must find out why.
The overheat lamp is not so easy because it is working with a rise of temperature instead of a loss of pressure.
Most modern dash monitor systems (if they are worth anything) have electronic circuits that will give the overheat detection circuit a self check of the bulb so the operator does not simply take off in ignorant bliss assuming that the bulb is good.
How does all this apply to your case?
If your overheat bulb is not working, you might never know whether your blades shut down due to an overheat.....or if there is another reason it happened. But to Lastec's credit, they have incorporated another way of protecting the engine and notifying the operator of an issue needing immediate attention. It would sure be nice to know if the overheat lamp lit up when the blades quit, but the bulb has to be working for that.
It is not necessary for the bulb to work in order for the overheat switch to stop the blades.

RE: pto on the ztr popped out of gear

Was hoping for a response from original poster about whether or not the machine does a bulb check when the key is turned on. If it doesn't, or if the overheat lamp does not illuminate during that time........there might be a broken wire and an intermittent short to ground on that circuit causing the PTO to drop out.

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