No Richard - I think that just negates Boberts notion that he can do it all by messing with just one of the multiple safety switches.

Current models at MTD show the same circuits with the same switches as on my 14 year old one. Since these switches are "OSHA Required" the simplest way for the makers to qualify their design is to use the same design everyone else uses, so I doubt that others are much different.

Making the seat switch always kill the engine just means it's in full parallel with the separate circuit branches containing the other switches, instead of being in a series/parallel connection, and that's a trivially simple change in the wire harness.

Since there are multiple kill switches, you have to change the connection for the one that controls the function you want to change. There most likely are four separate "safety switches" on Bobert's mower, and so far as he's mentioned he's only found one of them.

There's also a fuse, usually about 20A, buried in the wire harnesses, that he'll probably blow and won't be able to find before he gets done mucking with it(?) On most models it's "in the wire" and you have to replace the "wire assembly" to fix a blown fuse. (They usually don't sell that wire separately, so you're supposed to replace the whole wire harness.)

If getting off the seat always kills the engine it means that the seat swtich closes when you get off the seat and that switch grounds the distributor.

If the mower deck switch only kills the engine when you put it in reverse with the deck running, it means the deck switch is in series with the shift lever switch, so that both of those switches have to be closed to kill. Since this kills the engine even if the seat switch is open (if you're on the seat) the deck switch and the shift lever switch have to be in series in a separate branch of the circuit, and that branch is in parallel with the branch that contains the seat switch.

The main MTD mower that Sears sells is the MTD "Yardman" series. The wiring shown by MTD for the current version of that "brand name" model is identical to mine, although they don't indicate whether all the switches are in the same physical locations on all models.

The schematic for my wiring condition:

                  To Distributor/Magneto
             __________|__________
             |                   |
             X seat              X shift lever in reverse
             | empty             |
             |                   |
             X Not In            X deck running
             | Park              |
             |                   |
             |___________________|
                       |
                  To Ground

The "X" indicates a switch with the condition when it's CLOSED.

To kill the engine regardless of whether the Park/brake is set, the "Not in Park" switch would have to be removed, and replaced by a solid wire. This leaves one switch with an "undefined function" in other models, since the manuals all say there are four of them. OSHA can think up lots of other features to be required that might use it.

There are multiple other schematics you can draw to get the same logical AND/OR functions. This is just one of the simpler ones.

All the switches MUST be wired to kill the engine when the switch is CLOSED.

If either of "this switch" OR "that switch" can kill the engine, those two switches must be in PARALLEL circuits.

If "this switch" AND "that switch" are both required before the engine is killed, those two switches must be in the same SERIES circuit branch.

John