wiring puzzle

[38racing]

Friend asked me to fix a mower that he bought and had a tenant using it to cut grass at apartment building for rent credit. Had crankcase full of gas. The carb issue will be another thread. After doing the carb I was having some electrical issues when doing my test run. I had it running then it faltered. It is a 90 , 281707 and the coil kill wire goes to the insulated post on the throttle bracket and joins with the lead to the keyswitch. I determined that I had no spark. By disconnecting the lead to the keyswitch and the insulated terminal I got it running again. I pulled out the VOM to determine why the disconnected lead was grounded. At the keyswitch that wire is joined to another kill circuit involving the PTO switch , brake switch and seat switch. My readings just didn't seem to make sense, even tried another switch. Finally discover an issue with the brake switch. Push it a bit and switch opens as it should but push further it closes again. Finally I am at a point where it works right except for this. The brake/seat circuit is coil -> brake -> seat -> ground. The seat switch is a single pole normally closed plunger switch. It tests fine. PTO part of the seat circuit works fine. Engines runs with pto on and dies if you lift off seat. Put brake on to position where it is opening the circuit. Engine will run while off seat. Let brake out and engine will die but quickly press on seat and it recovers as it should . That is because seat switch , when pushed, has opened the circuit. So the puzzle is this. I disconnect the connector from the seat switch, effectively opening the circuit. I apply the brake and start the engine. It runs because brake is on opens the circuit ( and should run anyway since the seat circuit is open because plug is off) . But if I let out the brake the engine dies. I have the same wiring setup on other mowers and when a brake switch has acted up I have pulled a wire the seat switch to keep it running until I can fix the other switch. Only thing I'm thinking is that there is a short across the plug connector that is opened by the tabs of the seat switch? Guess I need a few more VOM readings on that disconnected plug. One lead is to ground , the other comes in parallel from PTO and brake .

[KE4AVB]

Yes some seat switch connectors has a built in shorting strip to prevent operators from simply unplugging the seat switch to defeat that safety feature.

[38racing]

Yes some seat switch connectors has a built in shorting strip to prevent operators from simply unplugging the seat switch to defeat that safety feature.

Well at least that would explain it. On my other unit the connector was replaced by just 2 leads, because a PO had eliminated all the safety wiring.