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I was distracted when I turned off my mower (Husqvarna 2754GLS) today. I had the mower engaged (was actively mowing) and I switched off the power using the ignition key. In other words, I forgot to disengage the mower blades before I shut off the mower.

Now the engine won't turn over at all. Not even when it's hooked up to my car's battery.
I checked the battery with a volt meter (an older one), and it registers 11 or 12 volts -- maybe that's low, but it should be doing *something*, at least a clicking noise. Especially when it's receiving active power from a running PT Cruiser!

Anyhow, my best guess is that the clutch (mower blade) is stuck in the "engaged" position -- but how do I disengage it? I don't fully understand the nature of the switch. It's not a button that just sends a signal, but it's also not a simple switch like the choke or the headlight switch, which can obviously be set when the mower is on or off. I think the "clutch engage" is something in-between.

Anyhow, how do I get my mower to run again? How do I make sure the mower blade engage/clutch is fully disengaged?

Thanks,

Matthew

You might have blown a fuse protecting the power take off system. The PTO clutch is an electromagnet that draws power whenever it is engaged. If it is drawing too much it can trip a breaker of blow a fuse. There should be a fuse or fuse panel under the dash with automotive type fuses, probably 15 or 20 amp. Might have blown one.

If it is the fuse......

TO REPLACE FUSE
Replace with 20 amp automotive-type plug-in fuse.
The fuse holder is located behind the dash.

EngineMan said:

If it is the fuse......

TO REPLACE FUSE
Replace with 20 amp automotive-type plug-in fuse.
The fuse holder is located behind the dash.

Click to expand...

Ok -- I looked into it further today.

I checked the fuse. I cleaned it (and air dusted the fuse holder) and tested the fuse on my multimeter -- it reads 0 Ohms (=0 resistance =good).

I also checked the battery with my digital multimeter -- it reads 12.57 volts. So the battery looks at least OK. At any rate, there is no reason the battery would up and die, unless the thing exploded or something (which didn't happen!)

I disconnected the battery for a good 20-25 minutes, to make sure the solenoid could reset itself.

I reattached the battery, and tried to start it. Still same result! Not even the slightest response when I put the key into the "start" position -- it's almost TOO quiet.

I'm as confused as ever.

Still sounds like a safety switch is tripped, which would cut power to the ignition switch. Locations are likely to be brakes, neutral switch on your transmission, drivers seat sensor, PTO switch, as well as the carb solenoid and coil kill circuits. That's why I suspected the PTO circuit. But it really could be any one of them. On my tractor, current has to make it past each of the safety switches before it gets a chance to energize the ignition switch. The idea is that if any of them trips the unit will shut down, or in the case of the PTO the blade will shut down. So if the tractor is off and the PTO switch is still on, the tractor will not crank. Turn the PTO switch off and the tractor will suddenly wake up.

TheCaffeinatedOne said:

Still sounds like a safety switch is tripped, which would cut power to the ignition switch. Locations are likely to be brakes, neutral switch on your transmission, drivers seat sensor, PTO switch, as well as the carb solenoid and coil kill circuits. That's why I suspected the PTO circuit. But it really could be any one of them. On my tractor, current has to make it past each of the safety switches before it gets a chance to energize the ignition switch. The idea is that if any of them trips the unit will shut down, or in the case of the PTO the blade will shut down. So if the tractor is off and the PTO switch is still on, the tractor will not crank. Turn the PTO switch off and the tractor will suddenly wake up.

Click to expand...

How can I get that PTO switch off, given that the mower won't start for me?
I tried disconnecting the battery for a length of time, thinking it would reset itself eventually.

See if you have battery volts at (S) on the key switch, then see if you have battery volts on the small wire (white) on the solenoid, if you don't have volts at solenoid check the PTO safety switch and/or Clutch/Brake switch.

I bypassed/shorted the solenoid with a wrench and was able to start the mower. This means several things:

The battery is OK, the starter is OK, the wiring is OK, enough gas, the parking brake is off, etc.

I mowed with it for a while, then disengaged the PTO and shut it off. Note: It took longer than usual to shut off.

Since bypassing the solenoid doesn't say anything about its health, I took it off and had it tested. Result: It is still good.

So it's looking more and more like there is something in one of the safety systems that's vetoing the starter's electricity.

I've attached the relevant pages from the manual -- the electrical system, wiring, etc.

Check white wire from ignition switch (s) to (c) PTO switch then (h) white wire PTO switch to clutch/brake switch white wire to solenoid, you should have continuity when all is good to start. (LOOK AT THE ELECTRICAL PDF)
you may also check (earth wire) black wire on solenoid to earth for continuity.

TexasDad76 said:

I mowed with it for a while, then disengaged the PTO and shut it off. Note: It took longer than usual to shut off.

Click to expand...

Hmm.... How much longer?
This is sounding like you have a number of things happening at once, which points to crud in the ignition switch.

For instance, two things should happen when you shut the unit off. The power to the carburetor solenoid is cut, and the two thin wires that go to your coils are shorted to ground. When the solenoid shuts off, the spring loaded needle valve it controls should close, shutting off fuel to the carburetor. The engine starves and dies in five or ten revolutions; it uses only what fuel is in the carburetor at the time. At the same time, when the coil kill wires are grounded, it creates a short in the coil primary circuit and the current finds, as the saying goes, "an alternate path to ground." It shorts out and when that happens there is nothing to excite a spark - the spark plugs go dead. Between the two the engine stops. Add to that the possibility of a flywheel brake and its even more so.

But all that switching is controlled at the key switch. So if it is shorting, or gummed up, or something else is wrong, maybe the carburetor solenoid is staying energized too long - the engine would try to continue running. And if the same switch is responsible for grounding the coil kill circuit, and doesn't, there is no reason for the motor to stop right then. You'll have a motor that continues to run when you shut it off, as you described. When both of these things to go wrong you look at the one common place affecting both circuits - the ignition switch which, by the way, might also be failing to send enough juice to the starter solenoid when you try to start it. When you shorted the starter solenoid, you bypassed the action of the ignition switch and energized the starter directly - which then did what it was told to do. All is consistent with a bad ignition switch.

The easiest way to test the theory is to swap out the ignition switch and see if the problem stops. If not, then hey - I'm a dunderhead.

I think I fixed the problem today -- the electric cables (3 wires total) going to the headlights were severed completely! I don't know how this happened. When I spliced them back together, everything started working normally again!

Well done...! :thumbsup:

Cool! Good work!

:drink:

I had the same problem after chasing my tale for a while I found what appears to be the only fuse on the mower. 20 amp located in what appeared to be a connector that was hanging under the battery on the switch side of the mower. Replaced the fuse and all is well.