You need a wiring diagram. I assume PTO doesn't work? If it's a simple 2 wire PTO then 13v one lead, 0v other (ground) is normal when engaged.
If I could see a schematic and problem description I could help.
You assume correctly, the PTO is not working. The PTO is a 2 wire but I measured the voltage from the connector going from the engine to the PTO clutch. The connector is three wire and the circuit goes from the the PTO switch and is connected to safety switches for PTO, seat, Rio and break. The mower does start but I’m getting voltage feedback with the the PTO switch not engaged. I ordered a new ignition switch (the switch was bad) and hoping that will solve the feedback problem. I’ll let you know if this corrects the problem.