Husqvarna YTH 24V48LS engine shut off when blades engaged

I have a Husqvarna YTH24V48LS lawn mower, engine starts runs all right, but every time when I pull up the blades engage switch, the engine shut off in a second, I checked the seat safety switch, off the four brass terminals, the two of most out side and the two of most inside both have their continuity when the switch is not pressed on. Can I have some advice to decide if this is what cause the engine shut off or there must be some thing else that cause the problem.
Thanks

Seat switch is toast .
One side should be normally open & the other normally closed.
They reverse when you sit on the seat.
The wiring diagram should be in the back of the parts book and the parts book is a free download from the Husqvarna web site .
You will need the numbers off the ID tag to make sure it is the right one.

You are correct, if the mower runs & drives fine but cuts out the instant you turn the blades on then the seat switch is a prime suspect.
The PTO switch could also be bad as could the wires between the two of them.
The cut out circuit is a ground circuit that grounds out the magneto so they are a PIA to find.

It is prudent to disconnect the kill wire at the coil when you are testing because if you accidentially send battery voltage down the wire by accident you will kill the magneto.

Thank you so much for the advices, I will replace the seat safety switch to begin with.

I would be inclined to make up a jumper lead to bypass the switch first.
There is more than one switch and they all look the same.

Thank you, I'll try to do it first.