Mower just keeps on cutting grass

[KE4AVB]

Here is one I got in Friday. Craftsman 917.271022
Wiring Diagram https://i.imgur.com/08Cj187.png

Engine spins starter without depressing clutch but will not fire up as long as the operator is off the seat.
Operator on the seat the start the engine without depressing the clutch.

And here is the one the operator brought the mower in for. He got knock off the mower while cutting grass and the mower just on cutting grass until he was able to catch the mower. BTW the seat switch working is working as intended per the diagram.

I can tell it is the results of someone not knowing anything about electrical working on it. One switch was removed. Just a guess what else they did to it which is requiring me to get two new switches.

[38racing]

So seat switch was ok for start circuit but obviously not for run circuit. I know this ariens I working on has seat switch bypassed. Friend says he did it so he could get off to empty bagger. He didn't want to shut engine off because of the restarting issue. I told him all he had to do was put brake on and he could get off. But I think he wanted to leave pto on too since it was having engagement issue. Not a safe way to operate.

[KE4AVB]

There absolutely nothing wrong with the seat switch or its circuit; it is your Normal NO SPST switch. The problem is related to the Brake/Clutch and PTO circuit.

As I said it is caused by someone that should never be working on electrical circuits. Most us probably would not have done this.

[38racing]

Any chance it was the input connector to the brake switch was jumpered to the output connector of the pto switch?

[KE4AVB]

Well there was jumpers but it was the PTO connector that jumpered but it could as well been the brake switch connector. And the brake switch connector plugged into the PTO switch. Now the PTO switch itself is the culprit of the weird operation. It is the wrong switch and only Husqvarna sells the correct switch which why the mower will be down a few more days until get my new distributor account approved [I hope]. If not then I got to order them from another vendor since TEW is gone.

Now can you figure out why the current PTO switch is the wrong one?

[38racing]

On many they are normally open for start and normally closed for seat kill when seat kill just grounds magneto. In this one the seat switch is current carrying. Much like the ariens of my friend and the Kubota t1400 I got. I wonder5if these relays systems were brought in to deter owners from trying to override the simpler setups.

[KE4AVB]

As for operation that is correct but these switches actually SPST NC switch (spring loaded in the normally closed position with monetary open position) on the grounding type circuits but it is also common to find them SPST NO (with monetary close position) when relays are involved. This Craftsman uses the SPST NO switch.

Now with the DPST switches used on the Clutch and PTO they are normally setup with one side NC and the other NO. But on this Craftsman the OEM used DPST NO/NO switches and the DYIer shop had put in the more common switch DPST NC/NO.

I stock both versions of the SPST seat switches but until this week I had not ran into the DPST NO/NO safety switches of the style use on this Craftsman. A rarity so I probably only get a couple extra for spares but I know my luck and if I don't then next another one would show up with a bad switch.

The switch specs are indicating the rest position and once depressed they switch modes.

SPST are single pole, single throw
DPST are double pole, single throw
NC is Normally Close
NO is Normally Open

[KE4AVB]

Boy what pain to install that brake switch but I got it in. Job Completed.

[hanz63]

Oh darn. I thought it was going to be like one those little Deeres that the deck only runs when you get off the seat things. Thanks for sharing.