Sorry if I'm not clear. Mower is an hour away at dad's and I'm at work so can't verify wire colors. I'm thinking this must be a bad safety switch.
If solenoid is as follows;
(A) large terminal, +12v from battery
(B) large terminal, solenoid switched/controlled +12v to starter
(C) small terminal, +12v from ignition when key is in "START" position
(D) small terminal, solenoid to ground
I can jump from + battery terminal to (C) with key in "ON" position and mower starts so solenoid, starter, etc are good. I'm assuming that with key in "ON" position vs "START" all safety switches are closed or out of the circuit.
A meter put on the wire from ignition to (C) showed 12v when key is in "START" position, however meter was grounded to battery terminal. I did not think to test with meter grounded to (D).
Do safety switches work by interrupting ground as opposed to preventing 12v from being sent to (C)? In other words they are between (D) and ground? If so that would explain why I always read 12v at (C) when grounding meter elsewhere but mower does not start when (C) & (D) are connected and switches are in the line and preventing (D) from reaching ground. If so I'm thinking I should be able to use jumper from (D) directly to ground thus bypassing switches and start mower thus confirming bad switch somewhere between (D) and ground.
Thanks again for your time and assistance
Thank you very much for the better description,
people forget you are there & I ( for example ) am at least 8,000 miles away so I can only work with what you tell me.
I do not have a SX/SR manual so can not be sure which wiring set up you have,
Generally the + feed to the solenoid terminal C goes through the starter switch, through the PTO switch through the brake switch then to the solenoid.
All of these are pass through switches in a chain, one not connection = nothing
Your dads mower looks like it has a neutral switch which powers a relay which breaks the ground connection to terminal D.
A but hard to tell because when I search for wiring diagrams I get a dozen variations.
That is why in the original post I asked you to try it with D jumpered to a good ground which would have covered all bases.
Some diagrams showed 2 relays and some showed 1 relay.
Unlike the other mower companies JD make excellent manuals with step by step instructions for both fault finding and repairs.
They can be downloaded at a small cost or ordered as a paper copy for a much higher cost from the JD web site.
Excellent value for money.
When I sell a used JD I include the technical manual with the mower and people pay near twice the price as ones without the manual go for.