Need Help Understanding a Circuit

Hey I am not sure if your circuit is correct because I can't figure out how Front/Rear PTO Lite would work in this arrangement.

But the diode there should be a reverse current protection diode that is used to prevent the current from the PTO (inductor) to discharge into the 12V (probably controlled). As we know inductors store charge when they powered and discharge when power is removed, so this diode prevents the inductor from discharging back into the 12V input pin.

The circuit will work even without the diode, but it increases the probability of the controller (from which 12V signal is provided) to fail 

Thank you for your response.  I double checked that my crude drawing does agree with the tractor schematic.   

I was thinking that the PTO lites will work since when +12V is applied to the diode cathodes, the diode will not conduct allowing the PTO interlock ground to complete the lite circuit.  (Indeed, the circuit does work;  I'm just puzzled by the way the diodes were implemented.)

The 12V comes directly from a normal car battery and has a rectifier to control the charging voltage, but I'm not aware of any need to provide special measures to protect that circuitry; it seems pretty bulletproof.  I had not considered the inductor discharge from the electromagnetic clutches.  Seems like that would be one more reason to place the diodes so that they would protect the interlock black box.  Anyway, the designers would have known that, so any ideas about why the circuit was made the way it is?  I feel like I'm missing something here.

Gerald