G'day folks,
This mower was in fact a manual start from the factory - that's what the M suffix denotes, apparently. It looks like these are an Italian made machine which are sold under a few different banners, apart from Stiga, in the EU. Castelgarden, Lawn King, Twincut are some of these.

A search under these names does come up with a few diagrams on parts sites, including a wiring harness one. This shows 4 NO switches [but not what actuates each one], a gearbox neutral switch, the circuit board, and a two wire connection to the engine, FWIW. https://www.diyspareparts.com/parts/castel--twincut--lawnking/diagrams/el63-m-ride-on/4289

However, what is really needed here is a full circuit diagram, to have any show of troubleshooting this setup.

I would guess that the diode board is in effect a 'logic circuit'; e.g. so that the seat switch is only operational if the machine state is that of in gear and/or cutter engaged.



Cheers,
Gadge

"ODK Mods can explain it to you, but they can't understand it for you..."

"Crazy can be medicated, ignorance can be educated - but there is no cure for stupid..."