Need electrical help Jacobsen

I have battled this for years. Today it has stopped running. I have a Jacobsen 445G turfcat mower. Front deck 72 inch cut. Since I acquired it, at times it would start with the key, others it would not. It would start by jumping at starter fine, but you got to lay on the ground to do it. It has several safety switches, seat, PTO, Parking brake, and tranny lockout. Recently it would die when you put tranny in gear, or turned on PTO. Today it died from the parking brake being released. It has a start circuit and run circuit for the switches and interlocks. I was wondering if one of you electrical gurus would look at the wiring schematic and see what is most likely cause. I put a new key switch on it, and the brake pedal switch today. Still nothing. I think it might be the tranny switch, but not smart enough to be able to tell. It started  after several attempts today after i wiggled the brake switch. After it warmed up, i moved pedal and it died instantly, this was with old limit switch on pedal. Any help appreciated . I have a copy of schematic but can't post it. I can text a copy if you want to help. Thanks a million! Tracy

lot of times, if the pto or brake is killing the motor, it is because the seat switch is bad or not stroking far enought  when you set on it.. switch is also makde so you can NOT bypass it and will NOT work if disconnected.... there is a terminal switch built into the PLUG... you might hold the switch in yoru hand and work it. push HARD and see if that makes it work... thyt are hard to test....   you can test the switch by itself for on - off contact.

Edited by steve(ill) - 03 Jun 2025 at 9:20am

Steve, I will give it a try! Thanks, Tracy

My 05 Simplicity zero would not start many times without twisting the key multiple time to get a click then finally a start. New ign and pto switch no fix. Spent a day crimping every wire end on every safety switch a little tighter and WAH LAH !!!

Edited by SteveM C/IL - 07 Jun 2025 at 9:58am

i dont know if your seat switch is a 2 wire or more... On the newer 2 wire units, the PLUG for the seat switch has a  jumper built into the spade terminal.. When you plug it in, the SWITCH grounds the system... When you disconnect the plug the PLUG grounds the system.. so it wont start .... If you pull the plug off, you need to stick a spade terminal into the plug to PUSH the jumper open for the GROUND circuit to be broken...When you SET on the seat, it also is suppose to open the circuit.. assuming the seat switch is working........ most of the Prints do not show this internal jumper as it would encourage people to CUT OFF THE PLUG.

Edited by steve(ill) - 8 hours 47 minutes ago at 7:40am

this would appear to be the TWO circuits of the igniton to GROUND... thru the brake, pto or  seat switche........ i think there are actually TWO CIRCUITS... the brake and neutral should just be to START... not continue to RUN...  the seat circuit is needed to START and RUN ?.. but BOTH go thru the PTO switch..

Edited by steve(ill) - 2 hours 20 minutes ago at 2:07pm