Safety Switch Sanity Check

[stillwegian]

Kubota T1870 started fine yesterday. After a couple of passes, I stopped to adjust cut height, raised deck, and disengaged PTO/blades. Mower died, and will not restart. No reaction at all when turning the key.

Assumed a problem with a safety switch. Pulled and tested (1) seat switch; (2) reverse switch (even though this shouldn't affect starting); (3) brake switch; (4) PTO switch. Seat and reverse switches are both one set of leads and both test open when plunger is out, and show continuity when plunger pressed.

The brake and PTO switches have two pairs of leads (they're the same model switch). It seems from research on here that one set should test open and one closed with the plunger out, and then closed/open with the plunger in. On both switches, both sets of leads test as open with plunger out, then both sets showed continuity when plunger pressed in. So it would seem that both of these switches are bad.

My question is: did these really both go bad at the same time? I tested the brake one first, and assumed it was the problem, but I tried jumping across the plug, and it still didn't start. So then I pulled the PTO switch, and it tested the same as the brake switch. (I didn't have another test lead to try to jump both at the same time.) So did they both fail simultaneously? If so, is that indicative of a bigger wiring issue?

 

[bertsmobile1]

IF the switches change continuity when the plunger is depressed then the switch is working
Down side is Kubota is almost as secretaive with their service information as Stihl is
So your service manual ( which should be very comprehensive ) has to be bought and paying $ 50 to answer a question I do not get paid to do is not going to happen
Many of us can stumble through most failure if we get good information
So for starters what engine is installed in your mower
Does it have a remote solenoid or a piggy back solenoid

 

[stillwegian]

It's a Kohler 19HP motor. The solenoid is mounted next to the started, so I assume that's a piggyback?

 

[bertsmobile1]

we call them Piggy-back you lot call them shift starters , potatoes / potartoes
So as we have 2 mowers with similar problems I will be lazy & do some cut & paste
From this thread which you might like to keep an eye on

Kohler 5400 won’t run.

Troy bilt Broncho with a Kohler 5400 19HP. I was mowing my field and it just stopped as though it was out of gas. It had gas, I turned the key, nothing. Just quiet. I tried jumping it from my truck, ( I’ve done that before.). Still nothing. Spark plug is attached properly. Any suggestions...

www.lawnmowerforum.com

After checking the fuse, and by checking I mean pull it out and look
The next step is to try & turn the engine over by hand
Place your palm on the debris screen and push down while turning clockwise
Do 2 full revolutions
If you can not then remove the spark plug & try again.
If you can turn the engine 2 full revolutions by hand then get some jumper leads
Hook one to the battery - and the other directly to a metal part on the engine then turn the key.
Engine cranks = bad battery ground cable
Do the similar with the battery + terminal to the + terminal on the starter motor
Engine spins = bad power cable

And I have to ask, you did reset the blade switch didn't you ?
although from your description the blades should have been turned off
We have al been there wondering why an engine will not crank only to find we have left the blade switch turned on .
If the fuse is good and you have power to the key switch then when your turn the key the carburettor solenoid should energise with a faint click
AFAIK no mower runs the carb solenoid through any other switch than the key switch
Also if it lost power then the engine would stop but that alone would not stop the engine from cranking, unless the wires to it got shorted which of course would blow the main fuse .
PTO & brake switches like to ones you describe are usually found on mowers with a kill relay rather than directly grounding the magneto through the key switch
And of course they could also use the same relay to tigger the starter motor solenoid
Like JD Kubota are quite fond of throwing relays in all over the place .

How did that saying go ?
Nothing so simple works so well that it can not be made better by making it more complicated and thus less reliable .

 

[Padroo]

I had a problem with a TORO a couple of years ago and it turned out one of the safety switches on the left lever was out of adjustment and not making contact. Once way before that TORO had a recall on the rollover switch. The cure was to bypass it. All those switches are in series and a pain to get to.