Help electrical component ID

[Chug]

I am fixing up my old ride on mower and have a problem with the electrics, the safety interlock switches work ok to stop the engine starting if it's in gear, or the pto is engaged or the rider is not in the seat, but it should also cut the engine spark if the rider leaves the seat whilst in gear or the pto is engaged but it's not.
There is only one component wired to the interlock system and the engine stop (magneto ground) but I don't know what it is called or how it works. I'm guessing it senses that the ground connection is lost if one of the switches is open and then sends a ground to the magneto, but I could be wrong.

Does anyone know what this component is called and how it works?

The brown wire is linked to pto interlock when rider is on the seat, then goes to the gearbox interlock then to starter solenoid ground, the yellow wire(looks orange in the pic) goes to starter solenoid ground and the red and black wire goes to the magneto ground.

there is a simple wiring diagram here. It's component number 29
https://www.jackssmallengines.com/jacks-parts-lookup/manufacturer/simplicity/simplicity/simplicity/riding-mowers/3100-series/1691439-3108e-rear-engine-rider-and-30-mower-deck/electrical-group-later-models-with-ground

[Chug]

After much staring at wiring circuits and webpages it seems my assumption was correct that when the ground circuit is lost by the interlock switches being open this gadget.....apparently called an Interlock Module DSI ....... sends a ground to the magneto .

The yellow and brown wires are both wired to ground via the two interlock switches and solenoid and mower seat sat on, and when the ground is lost in the interlock circuit this gadget senses it and sends a ground to the magneto via the red and black wire.

This interlock module dsi is no longer available from the manufacturer, but I've seen similar modules with just three wires for other mowers but not sure if they will do the job, I don't wanna blow anything.

Otherwise I was wondering if it's possible to use something else, a relay? to supply a ground to the magneto when the ground is lost from the mower seat being unoccupied?
or, change the seat switch to a switch that grounds the magneto when the seat is unoccupied?

[oakwoodtv]

https://www.mytractorforum.com/threads/can-dsi-interlock-be-bypassed.327425/

Had a look round the net on post 17 there is a diagram seems to be a logic type of device.

Will try to find out more later. 

[Chug]

yup thanks, seen that one Richard, and it's pretty identical to how mine is wired except I have no lights or fuel solenoid, and the red wire from the dsi is red and black on mine.

but what I didn't notice when looking at that forum before is the last post where he says the modules of that era are pretty much universal, so instead of 175 yankee bucks plus 30 post I have seen some for around £30

[Tony]

That's a pain.

I had a similar problem with a petrol chipper.  There's a deadlock switch that seems to ground out the coil if you open the hatch where all the spinning bits are that would make a mess of a human.  Fortunately the switch was the same as used somewhere on ice-cream vans and I managed to find a new one from China for a tenner.

Having searched for information on yours... no such luck.  Plenty of discussion on forums about how expensive they are to replace

[Chug]

I thought I had figured it out using two changeover relays but when the earth is cut when leaving the seat the engine cuts out, whether safety interlocks are open or closed so it's back to the drawing board!

[Chug]

After much brain ache and playing with relays and wires on the living room floor, I finally worked it out and got it all working this afternoon!

[Tony]

Painful, but satisfying! Always feels great to work out a problem like that.