Problems With Wiring Harness and No Start Issue

I have a Simplicity Regent, model 2690810. It has a 19.5HP Briggs with 38" deck.

Can someone please tell me what the difference, potentially in wiring/circuits, for harness numbers 1728097SM and 1760255YP? I have a Simplicity Regent, model number 2690810. It has a 31Q677-0123-B1 engine. The listings online, everywhere I looked, would indicate that my machine would have originally had the 1728097SM wiring harness. The machine is a 2009 from what I was told, but the serial number starts with 2014, so that's odd as well. Everywhere I called and also looked, told me that the 1728097SM harness was discontinued, so I ordered the 1760255YP, because it was still available. I have already ran the wiring, and verified connection by connection, plug for plug, replacing the old connection as I connected the connections on the new harness. I printed out the entire, colored wiring diagram, and have been over it front to back and top to bottom, at least 10 times. The only, and I mean only difference that I can see or noticed, is that the original harness had used all 6 spades on the key switch, while the new harness did not have the individual sixth lead, which as far as I can tell, is only an accessory circuit.

I cannot get the machine to start. Including myself, two other technicians, one of which is a master electrician, and the other the service manager with 32 years experience, have 9+ hours in this machine. There's power where/when there shouldn't be, and no power when/where there should be. Key switch is also new, and at the on position there's power, but none at start. Power is randomly hot when depressing parking brake and sitting in seat, when depression of the plunger on seat switch occurs. Engine wiring harnesses are their own thing, and that wasn't changed. The harness should be just based on chassis, and I'd have assumed whether it was using the 19.5HP Briggs or 23HP Kohler, the only difference would be the engine wiring itself. I don't know if I got a harness that was made on a Monday morning or Friday afternoon, but something ain't right.

I am in dire need of help. This is my personal machine, and I am getting reamed a new one for taking up shop space. Please help or advise. Thank you!

As bad luck would have it, on Briggs own parts lookup, and every dealer or parts website they're connected to, while they list TWO possible harnesses, one available and one discontinued. But, after finally getting top tier technical support from someone at Briggs....guess what, there's a third harness that my machine actually takes, that was listed NOWHERE on any parts lookup, and even though it's their mistake, they won't take the harness back, because I installed it. The third harness is being discontinued soon as well, and of course it's 70% more than the other one.

To answer the question, I know how to bypass, but apparently the internal routing on the harness I got (the wrong one), is no pun intended, wired different, so even though the colors matched, whatever is in the harness tape and what have you, was causing the issues. Bypassing would not have helped in this instance, and we had actually tried doing this in the shop.

The Briggs tech guy and I went circuit by circuit over the phone, and it's just stupid. There was some randomness with a Canadian model that the harness was actually for, and then there was listing of the harness I actually needed, but on models built with larger decks and a 12 volt power port and something else. I guess some didn't have the reverse switch option either. Maybe if they did the online lookup with both model AND serial number, this wouldn't have happened.

Personally, I think they should have given me the new harness for the same price as the other one, and taken the wrong one back. It was all their online parts lookup, and I think it's easier to get on the organ transplant list than it is to get anyone on the phone from Simplicity or Brigss.

Yes, the wiring harness is on order, with the standard B&S 2-10 day availability, follwed by a 3-5 day shipping out.

The wiring harness I had, between the three of us, we couldn't get it figured out. Without any key in the switch and switch turned, sitting on the seat would draw power from the battery. Engaging or disengaging the parking brake would draw power from the battery. It was a brand new battery with the plastic protectors on the terminals when installed after the harness and ignition switch. One of us disengaged the parking brake becuse it was on a lift; the battery drained overnight. Moving the seat from leaning against the steering wheel, to the seated position with a box of parts someone put on the seat was enough to engage the seat safety switch and after recharging the battery, that drained it overnight. Like I was saying previously, I think, turning switch to on had power, to start did not. Instead of reading zero or positive ohms on a meter, on/closed switches would read negative ohms; I've never seen that. They should be zero when on and a positive when off. The reverse switch was drawing voltage from the battery, and you can't even engage that without the engine running and PTO engaged. In the on position, obviously with it not running, pulling the PTO would cause a draw on the battery. Having everything correct per ironically the electrical circuit diagram (for the correct harness, unbeknownst to us), turning to start also fried two starter solenoids, like melted to the point that the terminals were not straight anymore, but bowed outwards. I honestly think there's a manufacturing defect in the harness, like the colors of wire were completely ignored or were randomized. No rhyme or reason to it, like gremlins in the system.

All of this started because my daughters f'd with it in the yard and I suddenly had no headlights last August I think. When I used some Scotchlocks, I think I crimped wrong because I was mad and then recrimped correctly, but I didn't electrical tape or heatshrink the exposure. Something touched something and it blew the main ground, like ignited underneath the raised metal battery tray. With it being like 16 years old, and how the wire burned, I had like an inch and a quarter of wire to crimp 3 wires into one, and it worked, for the front yard. I parked it to rehydrate and when I went back out, the crimp failed. At that point I didn't have enough length to do a new crimp, and at that time, I didn't pull the diagram. I probably could have traced it, taken apart the harness tape and ran new wire, but I have OCD, and I said, "self, this machine is 15 years old at the time. Wires get brittle and who knows what will fail next, let's just get a whole new harness and do it right". Life, work, and multiple extracurricular activities between two daughters happened and there wasn't room or time. I was off for like 10 days and got tired of looking at the thing in the yard, taunting me and giving me the finger every time I walked past, so I said F it, lets put the new harness in. I did a full harness rewire on my buddy's 69 camaro, so how difficult could a lawn tractor be?

If I were Briggs, I would want the harness back for internal testing, because who knows how many the moron that assembled this one has out there in the world. If the combined IQ and experience of the three of us that looked at it couldn't figure it out and get it to run, it was the harness and not installer/operator error, that's for certain. For them to not want it back to test it, and possibly reimburse me, makes me think they just don't care. I mean the tech expert guy told me basically, "yeah, that's not right", as we went over the whole thing. I had two full pages of notes on a 11 X 17 legal pad of things to go over, check, and ask. That's what prompted him, after we went through everything, to ask for the serial number. I'm glad it wasn't my Coronet, because that would have likely been a microfiche situation.