Started up...then died as if safety switch 18HP craftsman rider

Back side of dashboard. See manual.

https://www.manualslib.com/manual/480353/Craftsman-917-271120.html

To start, typical rider mower requires BRAKE ON, PTO OFF, and Transmission NEUTRAL. Some require operator in seat.

First of all check the battery is fully charged.
If OK check the battery terminals are clean and tight.
Check that the brake is on, gearbox in neutral and disengaged, mower disengaged and you are sitting on the seat. Many mowers have safety features to prevent starting unless these conditions are met. If it still fails to start, check the starting circuit, including the switch and the solenoid. Still no luck? Check the wiring to make sure there is not a short circuit in an of the starting wiring.

if you need to jump the solenoid to start it and it shuts down sounds to me that you have a bad safety switch start with the one on the pedal

There is a safety switch in the seat that shuts the mower off if there is no rider. The mower stays running when the rider gets up ONLY if the brake is set. The switch under your seat is broken and cannot sense that a rider is on the seat. Therefore, the engine can only run when the brake is set. Depending on the mower, the two wires need to be connected (or disconnected) when a rider is in place. I do't know what mode your mower needs but it shouldn't take long for you to figure it out.. The safest thing is to confirm the seat switch is the issue then change the seat if replacements are available. Good luck Please rate me Mark

there is a safety switch under the seat. to stay running after the brake is released or deck engaged you have to be sitting on the seat or it will die. if this switch is bad it will die as soon as you release the brake.

the seat switch may be bad or the cluch switch is bad

your mower deck safety switch is broke or it has come unhooked.this will cause it to die when you engage your blades .

Sounds like your rider safety switch is disconnected. When you enable the blades the rider presence switch (under the seat) must be made else the mower will quit.

It may possibly be the seat switch. There is a little button under your seat, it is a safety mechanism. It's so the mower won't start without someone actually sitting on it, it will also shut off atuomatically if you fall off. If your good at wiring, and splicing, you can cut the wires and splice them together, and see if it starts. Hope this helps a bit.